1
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Bocková J, Jones NC, Hoffmann SV, Meinert C. The astrochemical evolutionary traits of phospholipid membrane homochirality. Nat Rev Chem 2024; 8:652-664. [PMID: 39025922 DOI: 10.1038/s41570-024-00627-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/05/2024] [Indexed: 07/20/2024]
Abstract
Compartmentalization is crucial for the evolution of life. Present-day phospholipid membranes exhibit a high level of complexity and species-dependent homochirality, the so-called lipid divide. It is possible that less stable, yet more dynamic systems, promoting out-of-equilibrium environments, facilitated the evolution of life at its early stages. The composition of the preceding primitive membranes and the evolutionary route towards complexity and homochirality remain unexplained. Organics-rich carbonaceous chondrites are evidence of the ample diversity of interstellar chemistry, which may have enriched the prebiotic milieu on early Earth. This Review evaluates the detections of simple amphiphiles - likely ancestors of membrane phospholipids - in extraterrestrial samples and analogues, along with potential pathways to form primitive compartments on primeval Earth. The chiroptical properties of the chiral backbones of phospholipids provide a guide for future investigations into the origins of phospholipid membrane homochirality. We highlight a plausible common pathway towards homochirality of lipids, amino acids, and sugars starting from enantioenriched monomers. Finally, given their high recalcitrance and resistance to degradation, lipids are among the best candidate biomarkers in exobiology.
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Affiliation(s)
- Jana Bocková
- Institut de Chimie de Nice, CNRS UMR 7272, Université Côte d'Azur, Nice, France
| | - Nykola C Jones
- ISA, Department of Physics and Astronomy, Aarhus University, Aarhus, Denmark
| | - Søren V Hoffmann
- ISA, Department of Physics and Astronomy, Aarhus University, Aarhus, Denmark
| | - Cornelia Meinert
- Institut de Chimie de Nice, CNRS UMR 7272, Université Côte d'Azur, Nice, France.
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2
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Fortenberry RC. Quantum Chemistry and Astrochemistry: A Match Made in the Heavens. J Phys Chem A 2024; 128:1555-1565. [PMID: 38381079 DOI: 10.1021/acs.jpca.3c07601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/22/2024]
Abstract
Quantum chemistry can uniquely answer astrochemical questions that no other technique can provide. Computations can be parallelized, automated, and left to run continuously providing exceptional molecular throughput that cannot be done through experimentation. Additionally, the granularity of the individual computations that are required of potential energy surfaces, reaction mechanism pathways, or other quantum chemically derived observables produces a unique mosaic that make up the larger whole. These pieces can be dissected for their individual contributions or evaluated in an ad hoc fashion for each of their roles in generating the larger whole. No other scientific approach is capable of reporting such fine-grained insights. Quantum chemistry also works from a bottom-up approach in providing properties directly from the desired molecule instead of a top-down perspective as required of experiment where molecules have to be linked to observed phenomena. Furthermore, modern quantum chemistry is well within the range of "chemical accuracy" and is approaching "spectroscopic accuracy." As such, the seemingly difficult questions asked by astrochemistry that would not be asked initially for any other application require quantum chemical reference data. While the results of quantum chemical computations are needed to interpret astrochemical observation, modeling, or laboratory experimentation, such hard questions, regardless of the original need to answer them, produce unique solutions. While questions in astrochemistry often require novel developments in and implementations of quantum chemistry as outlined herein, the applications of these solutions will stretch beyond astrochemistry and may yet impact fields much closer to Earth.
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Affiliation(s)
- Ryan C Fortenberry
- Department of Chemistry & Biochemistry, University of Mississippi, Oxford, Mississippi 38677-1848, United States
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3
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Ingman ER, Laurinavicius D, Zhang J, Schrauwen JGM, Redlich B, Noble JA, Ioppolo S, McCoustra MRS, Brown WA. Infrared photodesorption of CO from astrophysically relevant ices studied with a free-electron laser. Faraday Discuss 2023; 245:446-466. [PMID: 37314039 DOI: 10.1039/d3fd00024a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
The infrared excitation and photodesorption of carbon monoxide (CO) and water-containing ices have been investigated using the FEL-2 free-electron laser light source at the FELIX laboratory, Radboud University, The Netherlands. CO-water mixed ices grown on a gold-coated copper substrate at 18 K were investigated. No CO photodesorption was observed, within our detection limits, following irradiation with light resonant with the C-O vibration (4.67 μm). CO photodesorption was seen as a result of irradiation with infrared light resonant with water vibrational modes at 2.9 μm and 12 μm. Changes to the structure of the water ice, which modifies the environment of the CO in the mixed ice, were also seen subsequent to irradiation at these wavelengths. No water desorption was observed at any wavelength of irradiation. Photodesorption at both wavelengths is due to a single-photon process. Photodesorption arises due to a combination of fast and slow processes of indirect resonant photodesorption (fast), and photon-induced desorption resulting from energy accumulation in the librational heat bath of the solid water (slow) and metal-substrate-mediated laser-induced thermal desorption (slow). Estimated cross-sections for the slow processes at 2.9 μm and 12 μm were found to be ∼7.5 × 10-18 cm2 and ∼4.5 × 10-19 cm2, respectively.
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Affiliation(s)
- Emily R Ingman
- Department of Chemistry, University of Sussex, Falmer, Brighton, BN1 9QJ, UK.
| | | | - Jin Zhang
- School of Electronic Engineering and Computer Science, Queen Mary University of London, London E1 4NS, UK
| | | | - Britta Redlich
- FELIX Laboratory, Radboud University, Nijmegen 6525 ED, The Netherlands
| | - Jennifer A Noble
- Physique des Interactions Ioniques et Moléculaires (PIIM), CNRS, Aix-Marseille Université, Marseille, France
- School of Physical Sciences, University of Kent, Canterbury, CT2 7NH, UK
| | - Sergio Ioppolo
- School of Electronic Engineering and Computer Science, Queen Mary University of London, London E1 4NS, UK
- Department of Physics and Astronomy, University of Aarhus, Ny Munkegade 120, 8000 Aarhus C, Denmark
| | | | - Wendy A Brown
- Department of Chemistry, University of Sussex, Falmer, Brighton, BN1 9QJ, UK.
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4
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Haug L, Griesser C, Thurner CW, Winkler D, Moser T, Thaler M, Bartl P, Rainer M, Portenkirchner E, Schumacher D, Dierschke K, Köpfle N, Penner S, Beyer MK, Loerting T, Kunze-Liebhäuser J, Klötzer B. A laboratory-based multifunctional near ambient pressure X-ray photoelectron spectroscopy system for electrochemical, catalytic, and cryogenic studies. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2023; 94:065104. [PMID: 37862508 DOI: 10.1063/5.0151755] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2023] [Accepted: 05/27/2023] [Indexed: 10/22/2023]
Abstract
A versatile multifunctional laboratory-based near ambient pressure x-ray photoelectron spectroscopy (XPS) instrument is presented. The entire device is highly customized regarding geometry, exchangeable manipulators and sample stages for liquid- and solid-state electrochemistry, cryochemistry, and heterogeneous catalysis. It therefore delivers novel and unique access to a variety of experimental approaches toward a broad choice of functional materials and their specific surface processes. The high-temperature (electro)catalysis manipulator is designed for probing solid state/gas phase interactions for heterogeneous catalysts including solid electrolyzer/fuel cell electrocatalysts at pressures up to 15 mbar and temperatures from room temperature to 1000 °C. The liquid electrochemistry manipulator is specifically designed for in situ spectroscopic investigations of polarized solid/liquid interfaces using aqueous electrolytes and the third one for experiments for ice and ice-like materials at cryogenic temperatures to approximately -190 °C. The flexible and modular combination of these setups provides the opportunity to address a broad spectrum of in situ and operando XPS experiments on a laboratory-based system, circumventing the limited accessibility of experiments at synchrotron facilities.
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Affiliation(s)
- Leander Haug
- Institute of Physical Chemistry, University of Innsbruck, Innrain 52c, 6020 Innsbruck, Austria
| | - Christoph Griesser
- Institute of Physical Chemistry, University of Innsbruck, Innrain 52c, 6020 Innsbruck, Austria
| | - Christoph W Thurner
- Institute of Physical Chemistry, University of Innsbruck, Innrain 52c, 6020 Innsbruck, Austria
| | - Daniel Winkler
- Institute of Physical Chemistry, University of Innsbruck, Innrain 52c, 6020 Innsbruck, Austria
| | - Toni Moser
- Institute of Physical Chemistry, University of Innsbruck, Innrain 52c, 6020 Innsbruck, Austria
| | - Marco Thaler
- Institute of Physical Chemistry, University of Innsbruck, Innrain 52c, 6020 Innsbruck, Austria
| | - Pit Bartl
- Institute of Physical Chemistry, University of Innsbruck, Innrain 52c, 6020 Innsbruck, Austria
| | - Manuel Rainer
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria
| | | | - David Schumacher
- SPECS Surface Nano Analysis GmbH, Voltastraße 5, 13355 Berlin, Germany
| | - Karsten Dierschke
- SPECS Surface Nano Analysis GmbH, Voltastraße 5, 13355 Berlin, Germany
| | - Norbert Köpfle
- Institute of Physical Chemistry, University of Innsbruck, Innrain 52c, 6020 Innsbruck, Austria
| | - Simon Penner
- Institute of Physical Chemistry, University of Innsbruck, Innrain 52c, 6020 Innsbruck, Austria
| | - Martin K Beyer
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria
| | - Thomas Loerting
- Institute of Physical Chemistry, University of Innsbruck, Innrain 52c, 6020 Innsbruck, Austria
| | - Julia Kunze-Liebhäuser
- Institute of Physical Chemistry, University of Innsbruck, Innrain 52c, 6020 Innsbruck, Austria
| | - Bernhard Klötzer
- Institute of Physical Chemistry, University of Innsbruck, Innrain 52c, 6020 Innsbruck, Austria
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5
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Tonauer CM, Fidler LR, Giebelmann J, Yamashita K, Loerting T. Nucleation and growth of crystalline ices from amorphous ices. J Chem Phys 2023; 158:141001. [PMID: 37061482 DOI: 10.1063/5.0143343] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/17/2023] Open
Abstract
We here review mostly experimental and some computational work devoted to nucleation in amorphous ices. In fact, there are only a handful of studies in which nucleation and growth in amorphous ices are investigated as two separate processes. In most studies, crystallization temperatures Tx or crystallization rates RJG are accessed for the combined process. Our Review deals with different amorphous ices, namely, vapor-deposited amorphous solid water (ASW) encountered in many astrophysical environments; hyperquenched glassy water (HGW) produced from μm-droplets of liquid water; and low density amorphous (LDA), high density amorphous (HDA), and very high density amorphous (VHDA) ices produced via pressure-induced amorphization of ice I or from high-pressure polymorphs. We cover the pressure range of up to about 6 GPa and the temperature range of up to 270 K, where only the presence of salts allows for the observation of amorphous ices at such high temperatures. In the case of ASW, its microporosity and very high internal surface to volume ratio are the key factors determining its crystallization kinetics. For HGW, the role of interfaces between individual glassy droplets is crucial but mostly neglected in nucleation or crystallization studies. In the case of LDA, HDA, and VHDA, parallel crystallization kinetics to different ice phases is observed, where the fraction of crystallized ices is controlled by the heating rate. A key aspect here is that in different experiments, amorphous ices of different "purities" are obtained, where "purity" here means the "absence of crystalline nuclei." For this reason, "preseeded amorphous ice" and "nuclei-free amorphous ice" should be distinguished carefully, which has not been done properly in most studies. This makes a direct comparison of results obtained in different laboratories very hard, and even results obtained in the same laboratory are affected by very small changes in the preparation protocol. In terms of mechanism, the results are consistent with amorphous ices turning into an ultraviscous, deeply supercooled liquid prior to nucleation. However, especially in preseeded amorphous ices, crystallization from the preexisting nuclei takes place simultaneously. To separate the time scales of crystallization from the time scale of structure relaxation cleanly, the goal needs to be to produce amorphous ices free from crystalline ice nuclei. Such ices have only been produced in very few studies.
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Affiliation(s)
- Christina M Tonauer
- Institute of Physical Chemistry, University of Innsbruck, 6020 Innsbruck, Austria
| | - Lilli-Ruth Fidler
- Institute of Physical Chemistry, University of Innsbruck, 6020 Innsbruck, Austria
| | - Johannes Giebelmann
- Institute of Physical Chemistry, University of Innsbruck, 6020 Innsbruck, Austria
| | - Keishiro Yamashita
- Institute of Physical Chemistry, University of Innsbruck, 6020 Innsbruck, Austria
| | - Thomas Loerting
- Institute of Physical Chemistry, University of Innsbruck, 6020 Innsbruck, Austria
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6
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Pavithraa S, Ramachandran R, Mifsud DV, Meka JK, Lo JI, Chou SL, Cheng BM, Rajasekhar BN, Bhardwaj A, Mason NJ, Sivaraman B. VUV photoabsorption of thermally processed carbon disulfide and ammonia ice mixtures - Implications for icy objects in the solar system. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2022; 283:121645. [PMID: 36037552 DOI: 10.1016/j.saa.2022.121645] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Revised: 07/13/2022] [Accepted: 07/15/2022] [Indexed: 06/15/2023]
Abstract
Many icy bodies in the solar system have been found to contain a rich mixture of simple molecules on their surfaces. Similarly, comets are now known to be a reservoir of molecules ranging from water to amides. The processing of planetary/cometary ices leads to the synthesis of more complex molecules some of which may be the harbingers of life. Carbon disulphide (CS2) and ammonia (NH3) are known to be present on many icy satellites and comets. Reactions involving CS2 and NH3 may lead to the formation of larger molecules that are stable under space conditions. In this paper we present temperature dependent VUV spectra of pure CS2 in the ice phase, and of CS2 and NH3 ices deposited as (i) layered, and (ii) mixed ices at 10 K and warmed to higher temperatures until their sublimation. Pure CS2 ice is found to have a broad absorption in the VUV region, which is unique for a small molecule in the ice phase. In layered and mixed ices, the molecules tend to affect the phase change and sublimation temperature of each other and also leave behind a form of CS2-NH3 complex after thermal annealing. This study of CS2-NH3 ice systems in layered and mixed configurations would support the detection of these species/complexes in mixed molecular ices analogous to that on planetary and cometary surfaces.
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Affiliation(s)
- S Pavithraa
- Physical Research Laboratory, Ahmedabad, India
| | | | - D V Mifsud
- Centre for Astrophysics and Planetary Science, School of Physical Sciences, University of Kent, Canterbury CT2 7NH, UK; Institute for Nuclear Research (Atomki), Debrecen 4026, Hungary
| | - J K Meka
- Physical Research Laboratory, Ahmedabad, India
| | - J I Lo
- Department of Medical Research, Hualien Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, Hualien, Taiwan
| | - S L Chou
- National Synchrotron Radiation Research Center, Taiwan
| | - Bing-Ming Cheng
- Department of Medical Research, Hualien Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, Hualien, Taiwan
| | | | | | - N J Mason
- Centre for Astrophysics and Planetary Science, School of Physical Sciences, University of Kent, Canterbury CT2 7NH, UK
| | - B Sivaraman
- Physical Research Laboratory, Ahmedabad, India.
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7
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Wilkins OH, Blake GA. Relationship between CH 3OD Abundance and Temperature in the Orion KL Nebula. J Phys Chem A 2022; 126:6473-6482. [PMID: 36000316 PMCID: PMC9514801 DOI: 10.1021/acs.jpca.2c01309] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
![]()
The relative abundances of singly deuterated methanol
isotopologues,
[CH2DOH]/[CH3OD], in star-forming regions deviate
from the statistically expected ratio of 3. In Orion KL, the nearest
high-mass star-forming region to Earth, the singly deuterated methanol
ratio is about 1, and the cause for this observation has been explored
through theory for nearly three decades. We present high-angular resolution
observations of Orion KL using the Atacama Large Millimeter/submillimeter
Array to map small-scale changes in CH3OD column density
across the nebula, which provide a new avenue to examine the deuterium
chemistry during star and planet formation. By considering how CH3OD column densities vary with temperature, we find evidence
of chemical processes that can significantly alter the observed gas-phase
column densities. The astronomical data are compared with existing
theoretical work and support D–H exchange between CH3OH and heavy water (i.e., HDO and D2O) at methanol’s
hydroxyl site in the icy mantles of dust grains. The enhanced CH3OD column densities are localized to the Hot Core-SW region,
a pattern that may be linked to the coupled evolution of ice mantle
chemistry and star formation in giant molecular clouds. This work
provides new perspectives on deuterated methanol chemistry in Orion
KL and informs considerations that may guide future theoretical, experimental,
and observational work.
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Affiliation(s)
- Olivia H Wilkins
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
| | - Geoffrey A Blake
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States.,Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, California 91125, United States
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8
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Baiano C, Lupi J, Barone V, Tasinato N. Gliding on Ice in Search of Accurate and Cost-Effective Computational Methods for Astrochemistry on Grains: The Puzzling Case of the HCN Isomerization. J Chem Theory Comput 2022; 18:3111-3121. [PMID: 35446575 PMCID: PMC9097295 DOI: 10.1021/acs.jctc.1c01252] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2021] [Indexed: 11/28/2022]
Abstract
The isomerization of hydrogen cyanide to hydrogen isocyanide on icy grain surfaces is investigated by an accurate composite method (jun-Cheap) rooted in the coupled cluster ansatz and by density functional approaches. After benchmarking density functional predictions of both geometries and reaction energies against jun-Cheap results for the relatively small model system HCN···(H2O)2, the best performing DFT methods are selected. A large cluster containing 20 water molecules is then employed within a QM/QM' approach to include a realistic environment mimicking the surface of icy grains. Our results indicate that four water molecules are directly involved in a proton relay mechanism, which strongly reduces the activation energy with respect to the direct hydrogen transfer occurring in the isolated molecule. Further extension of the size of the cluster up to 192 water molecules in the framework of a three-layer QM/QM'/MM model has a negligible effect on the energy barrier ruling the isomerization. Computation of reaction rates by the transition state theory indicates that on icy surfaces, the isomerization of HNC to HCN could occur quite easily even at low temperatures thanks to the reduced activation energy that can be effectively overcome by tunneling.
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Affiliation(s)
- Carmen Baiano
- Scuola Normale Superiore, Piazza Dei Cavalieri 7, I-56126 Pisa, Italy
| | - Jacopo Lupi
- Scuola Normale Superiore, Piazza Dei Cavalieri 7, I-56126 Pisa, Italy
| | - Vincenzo Barone
- Scuola Normale Superiore, Piazza Dei Cavalieri 7, I-56126 Pisa, Italy
| | - Nicola Tasinato
- Scuola Normale Superiore, Piazza Dei Cavalieri 7, I-56126 Pisa, Italy
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9
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Brann MR, Hansknecht SP, Muir M, Sibener SJ. Acetone-Water Interactions in Crystalline and Amorphous Ice Environments. J Phys Chem A 2022; 126:2729-2738. [PMID: 35452240 DOI: 10.1021/acs.jpca.2c01437] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We present research that systematically examines acetone interacting with various D2O ices of terrestrial and astrophysical interest using time-resolved, in situ reflection absorption infrared spectroscopy (RAIRS). We examine acetone deposited on top of different D2O ice films: high-density, nonporous amorphous (np-ASW), and crystalline (CI) films as well as porous amorphous (p-ASW) with various pore morphologies. Analysis of RAIR spectra changes after acetone exposure, and we find that more hydrogen bonding occurs between acetone and p-ASW ices as compared to acetone and np-ASW or CI ices. Hydrogen bonding quantification occurred by two independent RAIR spectral changes: a greater relative intensity of the 1703 cm-1 feature at low acetone coverage as part of a 14 cm-1 shift in the C═O region and an ∼30% integrated dangling bond area reduction after acetone exposure. Interestingly, when changing the water structure to be more porous (deposited at 70° compared to 30°), there is a further reduction in the amount of hydrogen bonding that occurs. This suggests that there is a lack of access to surface sites with dangling bonds in the pores as initial layers of acetone block the pores and acetone is unable to diffuse within the structure at low temperatures. In general, these results offer a clearer picture of the mechanisms that can occur when small organic hydrocarbons interact with various icy interfaces; a quantitative understanding of these interactions is essential for the accurate modeling of many astrophysical processes occurring on the surface of icy dust particles.
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Affiliation(s)
- Michelle R Brann
- The James Franck Institute and Department of Chemistry, The University of Chicago, 929 East 57th Street, Chicago, Illinois 60637, United States
| | - Stephen P Hansknecht
- The James Franck Institute and Department of Chemistry, The University of Chicago, 929 East 57th Street, Chicago, Illinois 60637, United States
| | - Mark Muir
- The James Franck Institute and Department of Chemistry, The University of Chicago, 929 East 57th Street, Chicago, Illinois 60637, United States
| | - S J Sibener
- The James Franck Institute and Department of Chemistry, The University of Chicago, 929 East 57th Street, Chicago, Illinois 60637, United States
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10
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Vishwakarma G, Malla BK, Methikkalam RRJ, Pradeep T. Rapid crystallization of amorphous solid water by porosity induction. Phys Chem Chem Phys 2022; 24:26200-26210. [DOI: 10.1039/d2cp02640f] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/14/2023]
Abstract
Rapid crystallization of amorphous solid water via acetonitrile diffusion–desorption induced porosity in the window of 128–134 K under ultrahigh vacuum.
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Affiliation(s)
- Gaurav Vishwakarma
- DST Unit of Nanoscience (DST UNS) and Thematic Unit of Excellence (TUE), Department of Chemistry, Indian Institute of Technology Madras, Chennai 600036, India
| | - Bijesh K. Malla
- DST Unit of Nanoscience (DST UNS) and Thematic Unit of Excellence (TUE), Department of Chemistry, Indian Institute of Technology Madras, Chennai 600036, India
| | | | - Thalappil Pradeep
- DST Unit of Nanoscience (DST UNS) and Thematic Unit of Excellence (TUE), Department of Chemistry, Indian Institute of Technology Madras, Chennai 600036, India
- International Centre for Clean Water, IIT Madras Research Park, Chennai 600113, India
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11
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Brann M, Hansknecht SP, Ma X, Sibener SJ. Differential Condensation of Methane Isotopologues Leading to Isotopic Enrichment under Non-equilibrium Gas-Surface Collision Conditions. J Phys Chem A 2021; 125:9405-9413. [PMID: 34658236 PMCID: PMC8558857 DOI: 10.1021/acs.jpca.1c07826] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Revised: 10/05/2021] [Indexed: 11/30/2022]
Abstract
We examine the initial differential sticking probability of CH4 and CD4 on CH4 and CD4 ices under nonequilibrium flow conditions using a combination of experimental methods and numerical simulations. The experimental methods include time-resolved in situ reflection-absorption infrared spectroscopy (RAIRS) for monitoring on-surface gaseous condensation and complementary King and Wells mass spectrometry techniques for monitoring sticking probabilities that provide confirmatory results via a second independent measurement method. Seeded supersonic beams are employed so that the entrained CH4 and CD4 have the same incident velocity but different kinetic energies and momenta. We found that as the incident velocity of CH4 and CD4 increases, the sticking probabilities for both molecules on a CH4 condensed film decrease systematically, but that preferential sticking and condensation occur for CD4. These observations differ when condensed CD4 is used as the target interface, indicating that the film's phonon and rovibrational densities of states, and collisional energy transfer cross sections, have a role in differential energy accommodation between isotopically substituted incident species. Lastly, we employed a mixed incident supersonic beam composed of both CH4 and CD4 in a 3:1 ratio and measured the condensate composition as well as the sticking probability. When doing so, we see the same effect in the condensed mixed film, supporting an isotopic enrichment of the heavier isotope. We propose that enhanced multi-phonon interactions and inelastic cross sections between the incident CD4 projectile and the CH4 film allow for more efficacious gas-surface energy transfer. VENUS code MD simulations show the same sticking probability differences between isotopologues as observed in the gas-surface scattering experiments. Ongoing analyses of these trajectories will provide additional insights into energy and momentum transfer between the incident species and the interface. These results offer a new route for isotope enrichment via preferential condensation of heavier isotopes and isotopologues during gas-surface collisions under specifically selected substrate, gas-mixture, and incident velocity conditions. They also yield valuable insights into gaseous condensation under non-equilibrium conditions such as occur in aircraft flight in low-temperature environments. Moreover, these results can help to explain the increased abundance of deuterium in solar system planets and can be incorporated into astrophysical models of interstellar icy dust grain surface processes.
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Affiliation(s)
- Michelle
R. Brann
- The James Franck Institute
and Department of Chemistry, The University
of Chicago, 929 E. 57th Street, Chicago, Illinois 60637, United
States
| | - Stephen P. Hansknecht
- The James Franck Institute
and Department of Chemistry, The University
of Chicago, 929 E. 57th Street, Chicago, Illinois 60637, United
States
| | - Xinyou Ma
- The James Franck Institute
and Department of Chemistry, The University
of Chicago, 929 E. 57th Street, Chicago, Illinois 60637, United
States
| | - S. J. Sibener
- The James Franck Institute
and Department of Chemistry, The University
of Chicago, 929 E. 57th Street, Chicago, Illinois 60637, United
States
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12
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Ingman ER, Shepherd A, Brown WA. Using Surface Science Techniques to Investigate the Interaction of Acetonitrile with Dust Grain Analogue Surfaces : Behaviour of acetonitrile and water on a graphitic surface. JOHNSON MATTHEY TECHNOLOGY REVIEW 2021. [DOI: 10.1595/205651321x16264409352535] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Surface science methodologies, such as reflection-absorption infrared spectroscopy (RAIRS) and temperature programmed desorption (TPD), are ideally suited to studying the interaction of molecules with model astrophysical surfaces. Here we describe the use of RAIRS and TPD to investigate
the adsorption, interactions and thermal processing of acetonitrile and water containing model ices grown under astrophysical conditions on a graphitic dust grain analogue surface. Experiments show that acetonitrile physisorbs on the graphitic surface at all exposures. At the lowest coverages,
repulsions between the molecules lead to a decreasing desorption energy with increasing coverage. Analysis of TPD data gives monolayer desorption energies ranging from 28.8‐39.2 kJ mol−1 and an average multilayer desorption energy of 43.8 kJ mol−1.
When acetonitrile is adsorbed in the presence of water ice, the desorption energy of monolayer acetonitrile shows evidence of desorption with a wide range of energies. An estimate of the desorption energy of acetonitrile from crystalline ice (CI) shows that it is increased to ~37 kJ mol−1
at the lowest exposures of acetonitrile. Amorphous water ice also traps acetonitrile on the graphite surface past its natural desorption temperature, leading to volcano and co-desorption. RAIRS data show that the C≡N vibration shifts, indicative of an interaction between the acetonitrile
and the water ice surface.
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Affiliation(s)
- Emily R. Ingman
- Department of Chemistry Arundel Building 305, School of Life Sciences, University of Sussex, Falmer, Brighton, BN1 9QJ UK
| | - Amber Shepherd
- Department of Chemistry Arundel Building 305, School of Life Sciences, University of Sussex, Falmer, Brighton, BN1 9QJ UK
| | - Wendy A. Brown
- Department of Chemistry Arundel Building 305, School of Life Sciences, University of Sussex, Falmer, Brighton, BN1 9QJ UK
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13
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Potapov A, McCoustra M. Physics and chemistry on the surface of cosmic dust grains: a laboratory view. INT REV PHYS CHEM 2021. [DOI: 10.1080/0144235x.2021.1918498] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Alexey Potapov
- Laboratory Astrophysics Group of the Max Planck Institute for Astronomy at the Friedrich Schiller University Jena, Jena, Germany
| | - Martin McCoustra
- Institute of Chemical Sciences, Heriot-Watt University, Edinburgh, UK
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14
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Stubbing JW, McCoustra MRS, Brown WA. A new technique for determining the refractive index of ices at cryogenic temperatures. Phys Chem Chem Phys 2020; 22:25353-25365. [PMID: 33140768 DOI: 10.1039/d0cp02373f] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A reflection-absorption optical (RAO) spectrometer, operating across the ultra-violet/visible (UV/visible) wavelength region, has been developed that allows simultaneous measurements of optical properties and thickness of thin solid films at cryogenic temperatures in ultrahigh vacuum. The RAO spectrometer enables such measurements to be made after ice deposition, as opposed to most current approaches which make measurements during deposition. This allows changes in the optical properties and in the thickness of the film to be determined subsequent to thermal, photon or charged particle processing. This is not possible with current techniques. A data analysis method is presented that allows the wavelength dependent n and k values for ices to be extracted from the reflection-absorption spectra. The validity of this analysis method is shown using model data from the literature. New data are presented for the reflection UV/visible spectra of amorphous and crystalline single component ices of benzene, methyl formate and water adsorbed on a graphite surface. These data show that, for benzene and methyl formate, the crystalline ice has a larger refractive index than amorphous ice, reflecting changes in the electronic environment occurring in the ice during crystallisation. For water, the refractive index does not vary with ice phase.
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Affiliation(s)
- James W Stubbing
- Department of Chemistry, School of Life Sciences, University of Sussex, Falmer, Brighton, BN1 9QJ, UK.
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15
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Potapov A, Jäger C, Henning T. Ice Coverage of Dust Grains in Cold Astrophysical Environments. PHYSICAL REVIEW LETTERS 2020; 124:221103. [PMID: 32567895 DOI: 10.1103/physrevlett.124.221103] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2020] [Revised: 04/14/2020] [Accepted: 05/01/2020] [Indexed: 06/11/2023]
Abstract
Surface processes on cosmic solids in cold astrophysical environments lead to gas-phase depletion and molecular complexity. Most astrophysical models assume that the molecular ice forms a thick multilayer substrate, not interacting with the dust surface. In contrast, we present experimental results demonstrating the importance of the surface for porous grains. We show that cosmic dust grains may be covered by a few monolayers of ice only. This implies that the role of dust surface structure, composition, and reactivity in models describing surface processes in cold interstellar, protostellar, and protoplanetary environments has to be reevaluated.
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Affiliation(s)
- Alexey Potapov
- Laboratory Astrophysics Group of the Max Planck Institute for Astronomy at the Friedrich Schiller University Jena, Institute of Solid State Physics, Helmholtzweg 3, 07743 Jena, Germany
| | - Cornelia Jäger
- Laboratory Astrophysics Group of the Max Planck Institute for Astronomy at the Friedrich Schiller University Jena, Institute of Solid State Physics, Helmholtzweg 3, 07743 Jena, Germany
| | - Thomas Henning
- Max Planck Institute for Astronomy, Königstuhl 17, D-69117 Heidelberg, Germany
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16
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Mensa-Bonsu G, Lietard A, Tozer DJ, Verlet JRR. Low energy electron impact resonances of anthracene probed by 2D photoelectron imaging of its radical anion. J Chem Phys 2020; 152:174303. [PMID: 32384861 DOI: 10.1063/5.0007470] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Electron-molecule resonances of anthracene were probed by 2D photoelectron imaging of the corresponding radical anion up to 3.7 eV in the continuum. A number of resonances were observed in both the photoelectron spectra and angular distributions, and most resonances showed clear autodetachment dynamics. The resonances were assigned using density functional theory calculations and are consistent with the available literature. Competition between direct and autodetachment, as well as signatures of internal conversion between resonances, was observed for some resonances. For the 12B2g resonance, a small fraction of population recovers the ground electronic state as evidenced by thermionic emission. Recovery of the ground electronic state offers a route of producing anions in an electron-molecule reaction; however, the energy at which this occurs suggests that anthracene anions cannot be formed in the interstellar medium by electron capture through this resonance.
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Affiliation(s)
- Golda Mensa-Bonsu
- Department of Chemistry, Durham University, Durham DH1 3LE, United Kingdom
| | - Aude Lietard
- Department of Chemistry, Durham University, Durham DH1 3LE, United Kingdom
| | - David J Tozer
- Department of Chemistry, Durham University, Durham DH1 3LE, United Kingdom
| | - Jan R R Verlet
- Department of Chemistry, Durham University, Durham DH1 3LE, United Kingdom
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17
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Pezzella M, Koner D, Meuwly M. Formation and Stabilization of Ground and Excited-State Singlet O 2 upon Recombination of 3P Oxygen on Amorphous Solid Water. J Phys Chem Lett 2020; 11:2171-2176. [PMID: 32059109 DOI: 10.1021/acs.jpclett.0c00130] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The recombination dynamics of 3P oxygen atoms on cold amorphous solid water to form triplet and singlet molecular oxygen (O2) is investigated under conditions representative of cold clouds. Reactive molecular dynamics simulations including Landau-Zener-based hopping to account for nonadiabatic transitions find that both ground-state (X3Σg-) O2 and molecular oxygen in the two lowest singlet states (a1Δg and b1Σg+) can be formed and the molecular species stabilize through vibrational relaxation. The relative populations of the species are approximately 1:1:1. These results also agree qualitatively with a kinetic model based on simplified wavepacket simulations. The presence and stabilization of higher electronic states of O2 are expected to modify the chemical evolution of cold interstellar (T ∼ 10-50 K) and warmer noctilucent (T ∼ 100 K) clouds.
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Affiliation(s)
- Marco Pezzella
- Department of Chemistry, University of Basel, Klingelbergstrasse 80, CH-4056 Basel, Switzerland
| | - Debasish Koner
- Department of Chemistry, University of Basel, Klingelbergstrasse 80, CH-4056 Basel, Switzerland
| | - Markus Meuwly
- Department of Chemistry, University of Basel, Klingelbergstrasse 80, CH-4056 Basel, Switzerland
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18
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Yocum KM, Smith HH, Todd EW, Mora L, Gerakines PA, Milam SN, Widicus Weaver SL. Millimeter/Submillimeter Spectroscopic Detection of Desorbed Ices: A New Technique in Laboratory Astrochemistry. J Phys Chem A 2019; 123:8702-8708. [PMID: 31556610 DOI: 10.1021/acs.jpca.9b04587] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
A new laboratory technique has been developed that utilizes gas-phase, direct-absorption millimeter and submillimeter spectroscopy to detect and identify desorbed species from interstellar and cometary ice analogues. Rotational spectroscopy is a powerful structure-specific technique for detecting isomers and other species possessing the same mass that are indistinguishable with mass spectrometry. Furthermore, the resultant laboratory spectra are directly comparable to observational data from far-infrared and millimeter telescopes. Here, we present the proof-of-concept measurements of the detection of thermally desorbed H2O, D2O, and CH3OH originating in a solid film created at low temperature (∼12 K). The surface binding energy of H2O is reported and compared to results from traditional techniques, including mass spectrometry and quartz-crystal microbalance measurements of mass loss. Lastly, we demonstrate that this technique can be used to derive thermodynamic values including the sublimation enthalpy and entropy of H2O.
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Affiliation(s)
- Katarina M Yocum
- Department of Chemistry , Emory University , Atlanta 30322 , Georgia , United States
| | - Houston H Smith
- Department of Chemistry , Emory University , Atlanta 30322 , Georgia , United States
| | - Ethan W Todd
- Department of Chemistry , Emory University , Atlanta 30322 , Georgia , United States
| | - Leslie Mora
- Department of Chemistry , Emory University , Atlanta 30322 , Georgia , United States
| | - Perry A Gerakines
- Astrochemistry Laboratory , NASA Goddard Space Flight Center , Greenbelt 20771 , Maryland , United States
| | - Stefanie N Milam
- Astrochemistry Laboratory , NASA Goddard Space Flight Center , Greenbelt 20771 , Maryland , United States
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19
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Ursini O, Angelini G, Cataldo F, Iglesias-Groth S. Fullerene Radiolysis in Astrophysical Ice Analogs: A Mass Spectrometric Study of the Products. ASTROBIOLOGY 2019; 19:903-914. [PMID: 31314590 DOI: 10.1089/ast.2018.1905] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The γ-radiolysis of fullerenes (C60 and C70) was performed to investigate the role of fullerenes as a carbon source in building organic molecules in astrophysical ice analog media. Mass spectrometric analyses and the sequential collision-induced dissociation processes enabled us to determine the plausible chemical structure of new products originated during γ-irradiation of fullerenes. The radiolytic products are grouped into six principal compound families. We assessed the relative yield, as percentage, for each new radiolytic compound, and designed the reaction schemes that lead to γ-irradiation products. The reactions start with the formation of primary radicals due to the radiolysis of solvents that react with the fullerenes' structures, forming fullerene radical adducts. The fate of these fullerene radical adducts depends on two factors: (i) the nature of radicals formed by irradiation of solvents and consequently by their ability to give secondary reactions, (ii) whether the onset of thermalization energy processes occurs or does not occur. Here, we present the results regarding the fragmentation processes that lead to functionalized carbonaceous chains characterized by lower molecular weight. We identify the chemical nature of functionalized chain products, propose the reaction schemes, and quantify their relative yields.
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Affiliation(s)
- Ornella Ursini
- 1CNR-Institute of Nanotechnology (CNR-Nanotec), Sapienza University of Rome, Piazzale A. Moro 2, 00185 Roma, Italy; second address: CNR-Istituto di Metodologie Chimiche, Area della Ricerca Roma 1, Via Salaria Km 29,300-00015 Monterotondo (Rome) Italy
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20
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Smith RS, Yuan C, Petrik NG, Kimmel GA, Kay BD. Crystallization growth rates and front propagation in amorphous solid water films. J Chem Phys 2019; 150:214703. [DOI: 10.1063/1.5098481] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- R. Scott Smith
- Physical Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99352, USA
| | - Chunqing Yuan
- Physical Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99352, USA
| | - Nikolay G. Petrik
- Physical Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99352, USA
| | - Greg A. Kimmel
- Physical Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99352, USA
| | - Bruce D. Kay
- Physical Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99352, USA
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21
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Bertoni C, Naclerio P, Viviani E, Dal Zilio S, Carrato S, Fraleoni-Morgera A. Nanostructured P3HT as a Promising SensingElement for Real-Time, Dynamic Detection ofGaseous Acetone. SENSORS 2019; 19:s19061296. [PMID: 30875845 PMCID: PMC6471540 DOI: 10.3390/s19061296] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/11/2019] [Revised: 02/20/2019] [Accepted: 02/28/2019] [Indexed: 12/21/2022]
Abstract
The dynamic response of gas sensors based on poly(3-hexylthiophene) (P3HT) nanofibers (NFs) to gaseous acetone was assessed using a setup based on flow-injection analysis, aimed at emulating actual breath exhalation. The setup was validated by using a commercially available sensor. The P3HT NFs sensors tested in dynamic flow conditions showed satisfactory reproducibility down to about 3.5 ppm acetone concentration, a linear response over a clinically relevant concentration range (3.5-35 ppm), excellent baseline recovery and reversibility upon repeated exposures to the analyte, short pulse rise and fall times (less than 1 s and about 2 s, respectively) and low power consumption (few nW), with no relevant response to water. Comparable responses’ decay times under either nitrogen or dry air suggest that the mechanisms at work is mainly attributable to specific analyte-semiconducting polymer interactions. These results open the way to the use of P3HT NFs-based sensing elements for the realization of portable, real-time electronic noses for on-the-fly exhaled breath analysis.
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Affiliation(s)
- Cristina Bertoni
- Global Connectivity & Technology-Robotics and Artificial Intelligence, Corso Lino Zanussi 24,33080 Porcia (PN), Italy.
| | - Pasquale Naclerio
- Department of Engineering and Architecture, University of Trieste, Via Valerio 10, 34127 Trieste, Italy.
| | - Emanuele Viviani
- Artificial Perception Laboratory, Department of Engineering and Architecture, University of Trieste,Via Valerio 10, 34127 Trieste, Italy.
| | - Simone Dal Zilio
- CNR-Istituto Officina dei Materiali, Strada Statale 14 km 163,5 - 34149 Basovizza, Trieste (TS), Italy.
| | - Sergio Carrato
- Department of Engineering and Architecture, University of Trieste, Via Valerio 10, 34127 Trieste, Italy.
| | - Alessandro Fraleoni-Morgera
- Flextronics Laboratory, Department of Engineering and Architecture, University of Trieste, Via Valerio 10,34127 Trieste, Italy.
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22
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Abstract
Amorphous solid water is probably the most abundant form of solid water in the universe. Its saturation vapor pressure and thermodynamic properties, however, are not well known. We have investigated the saturation vapor pressure over vapor-deposited amorphous ice at temperatures between 133 and 147 K using a novel experimental method. The new method determines the absolute vapor pressures and the sublimation rates by measuring the mass growth rates of ice-covered nanoparticles under supersaturated water vapor conditions. We find that the vapor pressure of amorphous solid water is up to a factor of 3 higher than that predicted by current parameterizations, which are based in part on calorimetric measurements. We demonstrate that the calorimetric measurements can be reconciled with our data by acknowledging the formation of nanocrystalline ice as an intermediate ice phase during the crystallization of amorphous ice. As a result, we propose a new value for the enthalpy of crystallization of amorphous solid water of Δ H = 2312 ± 227 J/mol, which is about 1000 J/mol higher than the current consensus. Our results shine a new light on the abundance of water ice clouds on Mars and mesospheric clouds on Earth and may alter our understanding of ice formation in the stratosphere.
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Affiliation(s)
- Mario Nachbar
- Institute of Environmental Physics , University of Heidelberg , Im Neuenheimer Feld 229 , 69120 Heidelberg , Germany
- Institute of Meteorology and Climate Research , Karlsruhe Institute of Technology-KIT , P.O. Box 3640, 76021 Karlsruhe , Germany
| | - Denis Duft
- Institute of Meteorology and Climate Research , Karlsruhe Institute of Technology-KIT , P.O. Box 3640, 76021 Karlsruhe , Germany
| | - Thomas Leisner
- Institute of Environmental Physics , University of Heidelberg , Im Neuenheimer Feld 229 , 69120 Heidelberg , Germany
- Institute of Meteorology and Climate Research , Karlsruhe Institute of Technology-KIT , P.O. Box 3640, 76021 Karlsruhe , Germany
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23
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Salter TL, Stubbing JW, Brigham L, Brown WA. A TPD and RAIRS comparison of the low temperature surface behavior of benzene, toluene, and xylene on graphite. J Chem Phys 2018; 149:164705. [DOI: 10.1063/1.5051134] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Tara L. Salter
- Department of Chemistry, School of Life Sciences, University of Sussex, Falmer, Brighton BN1 9QJ, United Kingdom
| | - James W. Stubbing
- Department of Chemistry, School of Life Sciences, University of Sussex, Falmer, Brighton BN1 9QJ, United Kingdom
| | - Lorna Brigham
- Department of Chemistry, School of Life Sciences, University of Sussex, Falmer, Brighton BN1 9QJ, United Kingdom
| | - Wendy A. Brown
- Department of Chemistry, School of Life Sciences, University of Sussex, Falmer, Brighton BN1 9QJ, United Kingdom
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24
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Agúndez M, Roueff E, Le Petit F, Le Bourlot J. The chemistry of disks around T Tauri and Herbig Ae/Be stars. ASTRONOMY AND ASTROPHYSICS 2018; 616:A19. [PMID: 30185991 PMCID: PMC6120683 DOI: 10.1051/0004-6361/201732518] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
CONTEXT Infrared and (sub-)mm observations of disks around T Tauri and Herbig Ae/Be stars point to a chemical differentiation between both types of disks, with a lower detection rate of molecules in disks around hotter stars. AIMS To investigate the underlying causes of the chemical differentiation indicated by observations we perform a comparative study of the chemistry of T Tauri and Herbig Ae/Be disks. This is one of the first studies to compare chemistry in the outer regions of these two types of disks. METHODS We developed a model to compute the chemical composition of a generic protoplanetary disk, with particular attention to the photochemistry, and applied it to a T Tauri and a Herbig Ae/Be disk. We compiled cross sections and computed photodissociation and photoionization rates at each location in the disk by solving the FUV radiative transfer in a 1+1D approach using the Meudon PDR code and adopting observed stellar spectra. RESULTS The warmer disk temperatures and higher ultraviolet flux of Herbig stars compared to T Tauri stars induce some differences in the disk chemistry. In the hot inner regions, H2O, and simple organic molecules like C2H2, HCN, and CH4 are predicted to be very abundant in T Tauri disks and even more in Herbig Ae/Be disks, in contrast with infrared observations that find a much lower detection rate of water and simple organics toward disks around hotter stars. In the outer regions, the model indicates that the molecules typically observed in disks, like HCN, CN, C2H, H2CO, CS, SO, and HCO+, do not have drastic abundance differences between T Tauri and Herbig Ae disks. Some species produced under the action of photochemistry, like C2H and CN, are predicted to have slightly lower abundances around Herbig Ae stars due to a narrowing of the photochemically active layer. Observations indeed suggest that these radicals are somewhat less abundant in Herbig Ae disks, although in any case the inferred abundance differences are small, of a factor of a few at most. A clear chemical differentiation between both types of disks concerns ices. Owing to the warmer temperatures of Herbig Ae disks, one expects snowlines lying farther away from the star and a lower mass of ices compared to T Tauri disks. CONCLUSIONS The global chemical behavior of T Tauri and Herbig Ae/Be disks is quite similar. The main differences are driven by the warmer temperatures of the latter, which result in a larger reservoir or water and simple organics in the inner regions and a lower mass of ices in the outer disk.
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Affiliation(s)
- Marcelino Agúndez
- Instituto de Física Fundamental, CSIC, C/ Serrano 123, E-28006 Madrid, Spain
| | - Evelyne Roueff
- Sorbonne Université, Observatoire de Paris, Université PSL, CNRS, LERMA, F-92190 Meudon, France
| | - Franck Le Petit
- Sorbonne Université, Observatoire de Paris, Université PSL, CNRS, LERMA, F-92190 Meudon, France
| | - Jacques Le Bourlot
- Sorbonne Université, Observatoire de Paris, Université PSL, CNRS, LERMA, F-92190 Meudon, France
- Université Paris-Diderot, Sorbonne Paris-Cité, F-75013 Paris, France
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25
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Stubbing JW, Salter TL, Brown WA, Taj S, McCoustra MRS. A fibre-coupled UHV-compatible variable angle reflection-absorption UV/visible spectrometer. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2018; 89:054102. [PMID: 29864813 DOI: 10.1063/1.5025405] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We present a novel UV/visible reflection-absorption spectrometer for determining the refractive index, n, and thicknesses, d, of ice films. Knowledge of the refractive index of these films is of particular relevance to the astrochemical community, where they can be used to model radiative transfer and spectra of various regions of space. In order to make these models more accurate, values of n need to be recorded under astronomically relevant conditions, that is, under ultra-high vacuum (UHV) and cryogenic cooling. Several design considerations were taken into account to allow UHV compatibility combined with ease of use. The key design feature is a stainless steel rhombus coupled to an external linear drive (z-shift) allowing a variable reflection geometry to be achieved, which is necessary for our analysis. Test data for amorphous benzene ice are presented as a proof of concept, the film thickness, d, was found to vary linearly with surface exposure, and a value for n of 1.43 ± 0.07 was determined.
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Affiliation(s)
- J W Stubbing
- Department of Chemistry, School of Life Sciences, University of Sussex, Falmer, Brighton BN1 9QJ, United Kingdom
| | - T L Salter
- Department of Chemistry, School of Life Sciences, University of Sussex, Falmer, Brighton BN1 9QJ, United Kingdom
| | - W A Brown
- Department of Chemistry, School of Life Sciences, University of Sussex, Falmer, Brighton BN1 9QJ, United Kingdom
| | - S Taj
- Institute of Chemical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, United Kingdom
| | - M R S McCoustra
- Institute of Chemical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, United Kingdom
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26
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Michoulier E, Ben Amor N, Rapacioli M, Noble JA, Mascetti J, Toubin C, Simon A. Theoretical determination of adsorption and ionisation energies of polycyclic aromatic hydrocarbons on water ice. Phys Chem Chem Phys 2018; 20:11941-11953. [PMID: 29667677 DOI: 10.1039/c8cp01175c] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In dense interstellar environments, Polycyclic Aromatic Hydrocarbons (PAHs) are likely to condense onto or integrate into water ice mantles covering dust grains. Understanding the role of ice in the photo-induced processes involving adsorbed PAHs is therefore a key issue in astrochemistry. This requires (i) the knowledge of PAH-ice interactions, i.e. PAH-ice adsorption energies and local structures at the PAH-ice interface, as well as (ii) the understanding of the fate of electrons in the PAH-ice system upon excitation. Regarding (i), in this work, we determined the lowest energy structures of PAH-ice systems for a variety of PAHs ranging from naphthalene to ovalene on three types of ice - crystalline (Ih and Ic) and amorphous (low density) - using an explicit description of the electrons and a finite-sized system. The electronic structure was determined using the Self Consistent Charge Density Functional based Tight Binding (SCC-DFTB) scheme with modified Mulliken charges in order to ensure a good description of the studied systems. Regarding (ii), the influence of the interaction with ice on the Vertical Ionisation Potentials (VIPs) of the series of PAHs was determined using the constrained SCC-DFTB scheme benchmarked against correlated wavefunction results for PAH-(H2O)n (n = 1-6, 13) clusters. The results show a deviation equal, at most, to ∼1.4 eV of the VIPs of PAHs adsorbed on ice with respect to the gas phase values. Our results are discussed in the light of experimental data and previous theoretical studies.
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Affiliation(s)
- Eric Michoulier
- Lab. Chim. & Phys. Quant. LCPQ IRSAMC, Univ. Toulouse [UPS] UPS & CNRS, UMR5626, 118 Route Narbonne, F-31062, Toulouse, France.
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27
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Ghosh J, Hariharan AK, Bhuin RG, Methikkalam RRJ, Pradeep T. Propane and propane-water interactions: a study at cryogenic temperatures. Phys Chem Chem Phys 2018; 20:1838-1847. [PMID: 29292468 DOI: 10.1039/c7cp06467e] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The phase transition of solid propane and a propane-water mixture under ultrahigh vacuum has been investigated using reflection absorption infrared spectroscopy (RAIRS) and temperature-programmed desorption mass spectrometry (TPD-MS). Here, the investigation is divided into two sections: the phase transition of pure propane and the interaction of propane with water. RAIR spectra of pure propane reveal an unknown crystalline phase at 50 K (phase I), which gradually converts to a known crystalline phase (phase II) at higher temperature. This conversion is associated with certain kinetics. Co-deposition of water and propane restricts the amorphous to crystalline phase transition, while sequential deposition (H2O@C3H8; propane over predeposited water) does not hinder it. For an alternative sequential deposition (C3H8@H2O; water over predeposited propane), the phase transition is hindered due to diffusional mixing within the given experimental time, which is attributed to the reason behind the restricted phase transition.
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Affiliation(s)
- Jyotirmoy Ghosh
- DST Unit of Nanoscience (DST UNS) and Thematic Unit of Excellence (TUE), Department of Chemistry, Indian Institute of Technology Madras, Chennai 600036, India.
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28
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Michoulier E, Noble JA, Simon A, Mascetti J, Toubin C. Adsorption of PAHs on interstellar ice viewed by classical molecular dynamics. Phys Chem Chem Phys 2018. [DOI: 10.1039/c8cp00593a] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The present work represents a complete description of PAH–ice interaction in the ground electronic state and at low temperature, providing the binding energies and barrier heights necessary to the ongoing improvement of astrochemical models.
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Affiliation(s)
- Eric Michoulier
- Laboratoire de Physique des Lasers
- Atomes et Molécules (PhLAM) UMR 8523 CNRS
- Université de Lille
- France
| | - Jennifer A. Noble
- Laboratoire de Physique des Lasers
- Atomes et Molécules (PhLAM) UMR 8523 CNRS
- Université de Lille
- France
- Institut des Sciences Moléculaires (ISM) – UMR 5255 CNRS
| | - Aude Simon
- Laboratoire de Chimie et Physique Quantiques (LCPQ) – IRSAMC UMR 5626 CNRS
- Université de Toulouse
- France
| | - Joëlle Mascetti
- Laboratoire de Chimie et Physique Quantiques (LCPQ) – IRSAMC UMR 5626 CNRS
- Université de Toulouse
- France
| | - Céline Toubin
- Laboratoire de Physique des Lasers
- Atomes et Molécules (PhLAM) UMR 8523 CNRS
- Université de Lille
- France
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29
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Smith RS, Kay BD. Desorption Kinetics of Benzene and Cyclohexane from a Graphene Surface. J Phys Chem B 2017; 122:587-594. [DOI: 10.1021/acs.jpcb.7b05102] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- R. Scott Smith
- Physical and Computational
Sciences Directorate, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - Bruce D. Kay
- Physical and Computational
Sciences Directorate, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
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Wakelam V, Loison JC, Mereau R, Ruaud M. Binding energies: New values and impact on the efficiency of chemical desorption. ACTA ACUST UNITED AC 2017. [DOI: 10.1016/j.molap.2017.01.002] [Citation(s) in RCA: 122] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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32
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Yuan C, Smith RS, Kay BD. Communication: Distinguishing between bulk and interface-enhanced crystallization in nanoscale films of amorphous solid water. J Chem Phys 2017; 146:031102. [DOI: 10.1063/1.4974492] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Affiliation(s)
- Chunqing Yuan
- Physical Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99352, USA
| | - R. Scott Smith
- Physical Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99352, USA
| | - Bruce D. Kay
- Physical Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99352, USA
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33
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Ayling SA, Burke DJ, Salter T, Brown WA. Desorption and crystallisation of binary 2-propanol and water ices adsorbed on graphite. RSC Adv 2017. [DOI: 10.1039/c7ra10410c] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Strong interactions between 2-propanol and water ice cause marked changes in the crystallisation kinetics and desorption of water.
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34
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Rosu-Finsen A, Marchione D, Salter TL, Stubbing JW, Brown WA, McCoustra MRS. Peeling the astronomical onion. Phys Chem Chem Phys 2016; 18:31930-31935. [DOI: 10.1039/c6cp05751a] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
This work presents a study of water mobility on interstellar dust grain analogues at temperatures as low as 18 K. The work indicates that water forms pure domains rather than covering the entire grain, thereby leaving bare dust grain surfaces available on which other molecules can adsorb as well as themselves providing surfaces for further adsorption from the interstellar gas.
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36
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Langlois GG, Li W, Gibson KD, Sibener SJ. Capture of Hyperthermal CO2 by Amorphous Water Ice via Molecular Embedding. J Phys Chem A 2015; 119:12238-44. [PMID: 26275022 DOI: 10.1021/acs.jpca.5b06287] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We present the first study detailing the capture and aggregation of hyperthermal CO2 molecules by amorphous solid water (ASW) under ultra-high vacuum conditions at 125 K, near the amorphous/crystalline transition. Using time-resolved in situ reflection-absorption infrared spectroscopy (RAIRS), CO2 molecules with translational energies above 3.0 eV are observed to directly embed underneath the vacuum-solid interface to become absorbed within the ice films despite an inability to adsorb at 125 K; this behavior is not observed for crystalline films. Upon embedding, the mobility of CO2 within 125 K amorphous ice and the strength of its intermolecular interactions result in its segregation into clusters within the ice films. Tracing the kinetics of CO2 embedding events under different energetic conditions allows for elucidation of the underlying dynamics, and we draw comparison with other projectiles we have studied to promote generalized conclusions in regard to empirical prediction of a projectile's embedding probability. Through application of a classical model of the entrance barrier for projectiles colliding with amorphous ice, we provide direct evidence for a unified connection between embedding probability and projectile momentum; an account of all embedding data measured by our group traces a unified barrier model. This work highlights the interplay between translational energy and momentum accommodation during collisions with ice in high speed gas flows.
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Affiliation(s)
- Grant G Langlois
- The James Franck Institute and Department of Chemistry, The University of Chicago , 929 E. 57th Street, Chicago, Illinois 60637, United States
| | - Wenxin Li
- The James Franck Institute and Department of Chemistry, The University of Chicago , 929 E. 57th Street, Chicago, Illinois 60637, United States
| | - K D Gibson
- The James Franck Institute and Department of Chemistry, The University of Chicago , 929 E. 57th Street, Chicago, Illinois 60637, United States
| | - S J Sibener
- The James Franck Institute and Department of Chemistry, The University of Chicago , 929 E. 57th Street, Chicago, Illinois 60637, United States
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37
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Smith RS, May RA, Kay BD. Desorption Kinetics of Ar, Kr, Xe, N2, O2, CO, Methane, Ethane, and Propane from Graphene and Amorphous Solid Water Surfaces. J Phys Chem B 2015; 120:1979-87. [DOI: 10.1021/acs.jpcb.5b10033] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- R. Scott Smith
- Physical
and Computational
Sciences Directorate, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - R. Alan May
- Physical
and Computational
Sciences Directorate, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - Bruce D. Kay
- Physical
and Computational
Sciences Directorate, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
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Burke DJ, Puletti F, Woods PM, Viti S, Slater B, Brown WA. Trapping and desorption of complex organic molecules in water at 20 K. J Chem Phys 2015; 143:164704. [PMID: 26520540 DOI: 10.1063/1.4934264] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The formation, chemical, and thermal processing of complex organic molecules (COMs) is currently a topic of much interest in interstellar chemistry. The isomers glycolaldehyde, methyl formate, and acetic acid are particularly important because of their role as pre-biotic species. It is becoming increasingly clear that many COMs are formed within interstellar ices which are dominated by water. Hence, the interaction of these species with water ice is crucially important in dictating their behaviour. Here, we present the first detailed comparative study of the adsorption and thermal processing of glycolaldehyde, methyl formate, and acetic acid adsorbed on and in water ices at astrophysically relevant temperatures (20 K). We show that the functional group of the isomer dictates the strength of interaction with water ice, and hence the resulting desorption and trapping behaviour. Furthermore, the strength of this interaction directly affects the crystallization of water, which in turn affects the desorption behaviour. Our detailed coverage and composition dependent data allow us to categorize the desorption behaviour of the three isomers on the basis of the strength of intermolecular and intramolecular interactions, as well as the natural sublimation temperature of the molecule. This categorization is extended to other C, H, and O containing molecules in order to predict and describe the desorption behaviour of COMs from interstellar ices.
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Affiliation(s)
- Daren J Burke
- Division of Chemistry, University of Sussex, Falmer, Brighton BN1 9QJ, United Kingdom
| | - Fabrizio Puletti
- Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, United Kingdom
| | - Paul M Woods
- Astrophysics Research Centre, School of Mathematics and Physics, Queen's University Belfast, University Road, Belfast BT7 1NN, United Kingdom
| | - Serena Viti
- Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, United Kingdom
| | - Ben Slater
- Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, United Kingdom
| | - Wendy A Brown
- Division of Chemistry, University of Sussex, Falmer, Brighton BN1 9QJ, United Kingdom
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Doronin M, Bertin M, Michaut X, Philippe L, Fillion JH. Adsorption energies and prefactor determination for CH3OH adsorption on graphite. J Chem Phys 2015; 143:084703. [DOI: 10.1063/1.4929376] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Affiliation(s)
- M. Doronin
- LERMA, Observatoire de Paris, PSL Research University, CNRS, Sorbonne Universités, UPMC Univ. Paris 06, F-75252 Paris, France
| | - M. Bertin
- LERMA, Observatoire de Paris, PSL Research University, CNRS, Sorbonne Universités, UPMC Univ. Paris 06, F-75252 Paris, France
| | - X. Michaut
- LERMA, Observatoire de Paris, PSL Research University, CNRS, Sorbonne Universités, UPMC Univ. Paris 06, F-75252 Paris, France
| | - L. Philippe
- LERMA, Observatoire de Paris, PSL Research University, CNRS, Sorbonne Universités, UPMC Univ. Paris 06, F-75252 Paris, France
| | - J.-H. Fillion
- LERMA, Observatoire de Paris, PSL Research University, CNRS, Sorbonne Universités, UPMC Univ. Paris 06, F-75252 Paris, France
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Burke DJ, Puletti F, Woods PM, Viti S, Slater B, Brown WA. Adsorption and Thermal Processing of Glycolaldehyde, Methyl Formate, and Acetic Acid on Graphite at 20 K. J Phys Chem A 2015; 119:6837-49. [DOI: 10.1021/acs.jpca.5b04010] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Daren J. Burke
- Division of Chemistry, University of Sussex, Falmer, Brighton BN1 9QJ, U.K
| | - Fabrizio Puletti
- Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, U.K
| | - Paul M. Woods
- Astrophysics Research
Centre, School of Mathematics and Physics, Queen’s University Belfast, University Road, Belfast BT7 1NN, U.K
| | - Serena Viti
- Department of Physics
and Astronomy, University College London, Gower Street, London WC1E 6BT, U.K
| | - Ben Slater
- Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, U.K
| | - Wendy A. Brown
- Division of Chemistry, University of Sussex, Falmer, Brighton BN1 9QJ, U.K
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42
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Amiaud L, Fillion JH, Dulieu F, Momeni A, Lemaire JL. Physisorption and desorption of H2, HD and D2 on amorphous solid water ice. Effect on mixing isotopologue on statistical population of adsorption sites. Phys Chem Chem Phys 2015; 17:30148-57. [DOI: 10.1039/c5cp03985a] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We study the adsorption and desorption of three isotopologues of molecular hydrogen mixed on 10 ML of porous amorphous water ice (ASW) deposited at 10 K.
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Affiliation(s)
- Lionel Amiaud
- Institut des Sciences Moléculaires d'Orsay (ISMO)
- CNRS
- University Paris-Sud
- Université Paris-Saclay
- F-91405 Orsay
| | | | - François Dulieu
- LERMA
- Observatoire de Paris
- PSL Research University
- CNRS
- Sorbonnes Universités
| | - Anouchah Momeni
- Institut des Sciences Moléculaires d'Orsay (ISMO)
- CNRS
- University Paris-Sud
- Université Paris-Saclay
- F-91405 Orsay
| | - Jean-Louis Lemaire
- Institut des Sciences Moléculaires d'Orsay (ISMO)
- CNRS
- University Paris-Sud
- Université Paris-Saclay
- F-91405 Orsay
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Gibson KD, Langlois GG, Li W, Killelea DR, Sibener SJ. Molecular interactions with ice: molecular embedding, adsorption, detection, and release. J Chem Phys 2014; 141:18C514. [PMID: 25399179 DOI: 10.1063/1.4895970] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The interaction of atomic and molecular species with water and ice is of fundamental importance for chemistry. In a previous series of publications, we demonstrated that translational energy activates the embedding of Xe and Kr atoms in the near surface region of ice surfaces. In this paper, we show that inert molecular species may be absorbed in a similar fashion. We also revisit Xe embedding, and further probe the nature of the absorption into the selvedge. CF4 molecules with high translational energies (≥3 eV) were observed to embed in amorphous solid water. Just as with Xe, the initial adsorption rate is strongly activated by translational energy, but the CF4 embedding probability is much less than for Xe. In addition, a larger molecule, SF6, did not embed at the same translational energies that both CF4 and Xe embedded. The embedding rate for a given energy thus goes in the order Xe > CF4 > SF6. We do not have as much data for Kr, but it appears to have a rate that is between that of Xe and CF4. Tentatively, this order suggests that for Xe and CF4, which have similar van der Waals radii, the momentum is the key factor in determining whether the incident atom or molecule can penetrate deeply enough below the surface to embed. The more massive SF6 molecule also has a larger van der Waals radius, which appears to prevent it from stably embedding in the selvedge. We also determined that the maximum depth of embedding is less than the equivalent of four layers of hexagonal ice, while some of the atoms just below the ice surface can escape before ice desorption begins. These results show that energetic ballistic embedding in ice is a general phenomenon, and represents a significant new channel by which incident species can be trapped under conditions where they would otherwise not be bound stably as surface adsorbates. These findings have implications for many fields including environmental science, trace gas collection and release, and the chemical composition of astrophysical icy bodies in space.
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Affiliation(s)
- K D Gibson
- The James Franck Institute and Department of Chemistry, The University of Chicago, 929 E. 57th Street, Chicago, Illinois 60637, USA
| | - Grant G Langlois
- The James Franck Institute and Department of Chemistry, The University of Chicago, 929 E. 57th Street, Chicago, Illinois 60637, USA
| | - Wenxin Li
- The James Franck Institute and Department of Chemistry, The University of Chicago, 929 E. 57th Street, Chicago, Illinois 60637, USA
| | - Daniel R Killelea
- Department of Chemistry and Biochemistry, Loyola University Chicago, 1068 W. Sheridan Ave., Chicago, Illinois 60660, USA
| | - S J Sibener
- The James Franck Institute and Department of Chemistry, The University of Chicago, 929 E. 57th Street, Chicago, Illinois 60637, USA
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Lupi L, Kastelowitz N, Molinero V. Vapor deposition of water on graphitic surfaces: Formation of amorphous ice, bilayer ice, ice I, and liquid water. J Chem Phys 2014; 141:18C508. [DOI: 10.1063/1.4895543] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Laura Lupi
- Department of Chemistry, The University of Utah, 315 South 1400 East, Salt Lake City, Utah 84112-0850, USA
| | - Noah Kastelowitz
- Department of Chemistry, The University of Utah, 315 South 1400 East, Salt Lake City, Utah 84112-0850, USA
| | - Valeria Molinero
- Department of Chemistry, The University of Utah, 315 South 1400 East, Salt Lake City, Utah 84112-0850, USA
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45
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He J, Vidali G. Application of a diffusion-desorption rate equation model in astrochemistry. Faraday Discuss 2014; 168:517-32. [PMID: 25302396 DOI: 10.1039/c3fd00113j] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Desorption and diffusion are two of the most important processes on interstellar grain surfaces; knowledge of them is critical for the understanding of chemical reaction networks in the interstellar medium (ISM). However, a lack of information on desorption and diffusion is preventing further progress in astrochemistry. To obtain desorption energy distributions of molecules from the surfaces of ISM-related materials, one usually carries out adsorption-desorption temperature programmed desorption (TPD) experiments, and uses rate equation models to extract desorption energy distributions. However, the often-used rate equation models fail to adequately take into account diffusion processes and thus are only valid in situations where adsorption is strongly localized. As adsorption-desorption experiments show that adsorbate molecules tend to occupy deep adsorption sites before occupying shallow ones, a diffusion process must be involved. Thus, it is necessary to include a diffusion term in the model that takes into account the morphology of the surface as obtained from analyses of TPD experiments. We take the experimental data of CO desorption from the MgO(100) surface and of D2 desorption from amorphous solid water ice as examples to show how a diffusion-desorption rate equation model explains the redistribution of adsorbate molecules among different adsorption sites. We extract distributions of desorption energies and diffusion energy barriers from TPD profiles. These examples are contrasted with a system where adsorption is strongly localized--HD from an amorphous silicate surface. Suggestions for experimental investigations are provided.
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Smith RS, Matthiesen J, Kay BD. Desorption Kinetics of Methanol, Ethanol, and Water from Graphene. J Phys Chem A 2014; 118:8242-50. [DOI: 10.1021/jp501038z] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- R. Scott Smith
- Fundamental and Computational
Sciences Directorate, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - Jesper Matthiesen
- Fundamental and Computational
Sciences Directorate, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - Bruce D. Kay
- Fundamental and Computational
Sciences Directorate, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
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47
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Karssemeijer LJ, de Wijs GA, Cuppen HM. Interactions of adsorbed CO2 on water ice at low temperatures. Phys Chem Chem Phys 2014; 16:15630-9. [DOI: 10.1039/c4cp01622j] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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48
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Mitterdorfer C, Bauer M, Youngs TGA, Bowron DT, Hill CR, Fraser HJ, Finney JL, Loerting T. Small-angle neutron scattering study of micropore collapse in amorphous solid water. Phys Chem Chem Phys 2014; 16:16013-20. [DOI: 10.1039/c4cp00593g] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Amorphous solid water (ASW) is shown to undergo a micropore collapse from cylindrical pores (3D) to lamellae (2D) at >120 K using small-angle neutron scattering.
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Affiliation(s)
| | - Marion Bauer
- Institute of General
- Inorganic and Theoretical Chemistry
- University of Innsbruck
- A-6020 Innsbruck, Austria
| | | | - Daniel T. Bowron
- ISIS Facility
- Rutherford Appleton Laboratory
- Harwell Oxford
- Didcot, UK
| | - Catherine R. Hill
- Department of Physical Sciences
- The Open University
- Milton Keynes MK7 6AA, UK
| | - Helen J. Fraser
- Department of Physical Sciences
- The Open University
- Milton Keynes MK7 6AA, UK
| | - John L. Finney
- Department of Physics and Astronomy and London Centre for Nanotechnology
- University College London
- London WC1E 6BT, UK
| | - Thomas Loerting
- Institute of Physical Chemistry
- University of Innsbruck
- A-6020 Innsbruck, Austria
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Kimber HJ, Ennis CP, Price SD. Single and double addition of oxygen atoms to propyne on surfaces at low temperatures. Faraday Discuss 2014; 168:167-84. [DOI: 10.1039/c3fd00130j] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Experiments designed to simulate the low temperature surface chemistry occurring in interstellar clouds provide clear evidence of a reaction between oxygen atoms and propyne ice. The reactants are dosed onto a surface held at a fixed temperature between 14 and 100 K. After the dosing period, temperature programmed desorption (TPD), coupled with time-of-flight mass spectrometry, are used to identify two reaction products with molecular formulae C3H4O and C3H4O2. These products result from the addition of a single oxygen atom, or two oxygen atoms, to a propyne reactant. A simple model has been used to extract kinetic data from the measured yield of the single-addition (C3H4O) product at surface temperatures from 30–100 K. This modelling reveals that the barrier of the solid-state reaction between propyne and a single oxygen atom (160 ± 10 K) is an order of magnitude less than that reported for the gas-phase reaction. In addition, estimates for the desorption energy of propyne and reaction rate coefficient, as a function of temperature, are determined for the single addition process from the modelling. The yield of the single addition product falls as the surface temperature decreases from 50 K to 30K, but rises again as the surface temperature falls below 30 K. This increase in the rate of reaction at low surface temperatures is indicative of an alternative, perhaps barrierless, pathway to the single addition product which is only important at low surface temperatures. The kinetic model has been further developed to characterize the double addition reaction, which appears to involve the addition of a second oxygen atom to C3H4O. This modelling indicates that this second addition is a barrierless process. The kinetic parameters we extract from our experiments indicate that the reaction between atomic oxygen and propyne could occur under on interstellar dust grains on an astrophysical time scale.
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