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Malicka MI, Field RW, Ryzner S, Stasik A, Ubachs W, Heays AN, de Oliveira N, Szajna W, Hakalla R. FT-spectroscopy of the 12C 18O rare isotopologue and deperturbation analysis of the A 1Π(v = 3) level. Spectrochim Acta A Mol Biomol Spectrosc 2024; 312:124011. [PMID: 38428210 DOI: 10.1016/j.saa.2024.124011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2023] [Revised: 02/01/2024] [Accepted: 02/05/2024] [Indexed: 03/03/2024]
Abstract
Research on 12C18O was carried out using two complementary Fourier-transform methods: (1) vacuum-ultraviolet absorption spectroscopy, with an accuracy ca. 0.03 cm-1 on the DESIRS beamline (SOLEIL synchrotron) and (2) visible emission spectroscopy with an accuracy of about 0.005-0.007 cm-1 by means of the Bruker IFS 125HR spectrometer (University of Rzeszów). The maximum rotational quantum number of the energy levels involved in the observed spectral lines was Jmax = 54. An effective Hamiltonian and the term-value fitting approach were implemented for the precise analysis of the A1Π(v = 3) level in 12C18O. It was performed by means of the PGOPHER code. The data set consisted of 571 spectral lines belonging to the A1Π-X1Σ+(3, 0), B1Σ+-A1Π(0, 3), C1Σ+-A1Π(0, 3) bands and several lines involving states that perturb the A1Π(v = 3) level as well as to the previously analysed B1Σ+-X1Σ+(0, 0) and C1Σ+-X1Σ+(0, 0) transitions. A significantly extended quantum-mechanical description of the A1Π(v = 3) level in 12C18O was provided. It consists of the 5 new unimolecular interactions of the spin-orbit and rotation-electronic nature, which had not been taken into account previously in the literature. The ro-vibronic term values of the A1Π(v = 3, Jmax = 55), a'3Σ+(v = 13), D1Δ(v = 4) and I1Σ-(v = 5) levels were determined with precision improved by a factor of 10 relative to the previously known values.
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Affiliation(s)
- M I Malicka
- The Faculty of Mathematics and Applied Physics, Rzeszów University of Technology, Powstańców Warszawy 8 Street, 35-959, Rzeszów, Poland.
| | - R W Field
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge MA02139, USA
| | - S Ryzner
- Materials Spectroscopy Laboratory, Institute of Physics, University of Rzeszów, Pigonia 1 Street, 35-310 Rzeszów, Poland; Doctoral School of the University of Rzeszów, University of Rzeszów, Rejtana 16C Street, 35-959 Rzeszów, Poland
| | - A Stasik
- Materials Spectroscopy Laboratory, Institute of Physics, University of Rzeszów, Pigonia 1 Street, 35-310 Rzeszów, Poland
| | - W Ubachs
- Department of Physics and Astronomy, and LaserLaB, Vrije Universiteit, De Boelelaan 1081, 1081 HV Amsterdam, the Netherlands
| | - A N Heays
- J. Heyrovský Institute of Physical Chemistry, Dolejškova 2155/3, 182 23 Prague 8, Czech Republic
| | - N de Oliveira
- Synchrotron SOLEIL, Orme de Merisiers, St. Aubin, BP 48, F-91192 Gif sur Yvette Cedex, France
| | - W Szajna
- Materials Spectroscopy Laboratory, Institute of Physics, University of Rzeszów, Pigonia 1 Street, 35-310 Rzeszów, Poland
| | - R Hakalla
- Materials Spectroscopy Laboratory, Institute of Physics, University of Rzeszów, Pigonia 1 Street, 35-310 Rzeszów, Poland
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Mishra P, Hull AW, Coy SL, Field RW. Signatures of Reaction Mechanisms Encoded in the Vibrational Population Distribution of Small-Molecule Products: Photodissociation of Symmetric-Triazine Using 266 nm Radiation. J Phys Chem Lett 2023; 14:3706-3711. [PMID: 37040597 DOI: 10.1021/acs.jpclett.3c00597] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
We utilize rotationally resolved Chirped-Pulse Fourier Transform millimeter-wave spectroscopy to study photodissociation dynamics of 1,3,5-Triazine (symmetric-Triazine) to form 3 HCN molecules. The state-specific vibrational population distribution (VPD) of the photofragments contains mechanistic details of the reaction. This photodissociation is performed using 266 nm radiation transverse to a seeded supersonic jet. The vibrational cooling inefficiency in the jet preserves the VPD of the photofragments, while rotational cooling enhances the signal of low-J pure-rotational transitions. The multiplexed nature of the spectrometer enables simultaneous sampling of several "vibrational satellites" of the J = 1 ← 0 transition of HCN. Excited state populations along the HCN bend (v2) and CN stretch (v3) modes are observed, which show ≥3.2% vibrational excitation of the photofragments. Observation of an at least bimodal VPD, along the even-v states of v2, implies an asymmetric partitioning of vibrational energy among the HCN photofragments. This suggests a sequential dissociation mechanism of symmetric-Triazine initiated by 266 nm radiation.
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Affiliation(s)
- Piyush Mishra
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Alexander W Hull
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Stephen L Coy
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Robert W Field
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
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Ryzner S, Malicka MI, Heays AN, Field RW, de Oliveira N, Szajna W, Ubachs W, Hakalla R. VUV-VIS FT spectroscopy of the rare 13C 18O isotopologue of carbon monoxide: Analysis of the A 1Π(v = 1) multiply-perturbed level. Spectrochim Acta A Mol Biomol Spectrosc 2022; 279:121367. [PMID: 35653807 DOI: 10.1016/j.saa.2022.121367] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2022] [Revised: 05/05/2022] [Accepted: 05/06/2022] [Indexed: 06/15/2023]
Abstract
Ro-vibronic spectra of the 13C18O carbon monoxide isotopologue were obtained with (i) emission spectroscopy in the visible region using a Bruker IFS 125HR spectrometer (University of Rzeszów) and (ii) vacuum-ultraviolet absorption spectroscopy using the wave-front-division spectrometer on the DESIRS beamline of the SOLEIL synchrotron. A deperturbation analysis of the 13C18O A1Π(v = 1) level was conducted from 598 observed transitions from the B1Σ+ - A1Π(0, 1), C1Σ+ - A1Π(0, 1), A1Π - X1Σ+(1, 0), B1Σ+ - X1Σ+(0, 0), C1Σ+ - X1Σ+(0, 0), I1Σ- - X1Σ+(2, 0) bands and five further nominally forbidden bands. An effective Hamiltonian and term-value fitting analysis was implemented. Consequently, 135 parameters were floated: 23 molecular parameters, including molecular constants for A1Π(v = 1), I1Σ-(v = 2), d3Δ(v = 6), e3Σ-(v = 3) and D1Δ(v = 1); rotation-electronic (L-uncoupling) mixing of A1Π(v = 1) ∼ [D1Δ(v = 1), I1Σ-(v = 1), I1Σ-(v = 2)] and spin-orbit interaction parameters for A1Π(v = 1) ∼ [d3Δ(v = 6), e3Σ-(v = 3), a'3Σ+(v = 11)]; the spin-orbit/spin-electronic/L-uncoupling a3Π(v = 12) ∼ d3Δ(v = 5) and spin-orbit a3Π(v = 12) ∼ [D1Δ(v = 1), I1Σ-(v = 2)] perturbation parameters; as well as 112 ro-vibronic term values of B1Σ+(v = 0) up to J = 50 and C1Σ+(v = 0) up to J = 60. The significant, indirect a3Π(v = 12) ∼ [e3Σ-(v = 2, 3), d3Δ(v = 5, 6)] ∼ A1Π(v = 1) spin-orbit/spin-electronic/L-uncoupling interaction and a3Π(v = 12) ∼ [I1Σ-(v = 2), D1Δ(v = 1)] ∼ A1Π(v = 1) spin-orbit/L-uncoupling interaction were detected and analysed. Thus, this study, using modern experimental methods and deperturbation analysis, leads to a much improved description in terms of molecular constants and interaction parameters, compared to previous studies of the A1Π(v = 1) energy region in the 13C18O isotopologue. This research is a continuation of the studies on the A1Π state and its numerous perturbers in the CO isotopologues made by our team.
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Affiliation(s)
- Stanisław Ryzner
- Materials Spectroscopy Laboratory, Institute of Physics, University of Rzeszów, Pigonia 1 Street, Rzeszów 35-310, Poland
| | - Marzena I Malicka
- The Faculty of Mathematics and Applied Physics, Rzeszów University of Technology, Powstańców Warszawy 8 Street, Rzeszów 35-959, Poland
| | - Alan N Heays
- J. Heyrovský Institute of Physical Chemistry, Dolejškova 2155/3, Prague 8 182 23, Czech Republic
| | - Robert W Field
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA02139, USA
| | - Nelson de Oliveira
- Synchrotron SOLEIL, Orme de Merisiers, St. Aubin, BP 48, Gif sur Yvette Cedex, F-91192, France
| | - Wojciech Szajna
- Materials Spectroscopy Laboratory, Institute of Physics, University of Rzeszów, Pigonia 1 Street, Rzeszów 35-310, Poland
| | - Wim Ubachs
- Department of Physics and Astronomy, and LaserLaB, Vrije Universiteit, De Boelelaan 1081, Amsterdam, 1081 HV, Netherlands
| | - Rafał Hakalla
- Materials Spectroscopy Laboratory, Institute of Physics, University of Rzeszów, Pigonia 1 Street, Rzeszów 35-310, Poland.
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Virga E, Field RW, Biesheuvel PM, de Vos WM. Theory of oil fouling for microfiltration and ultrafiltration membranes in produced water treatment. J Colloid Interface Sci 2022; 621:431-439. [PMID: 35483176 DOI: 10.1016/j.jcis.2022.04.039] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2022] [Revised: 04/05/2022] [Accepted: 04/06/2022] [Indexed: 10/18/2022]
Abstract
Due to the complexity of oil-in-water emulsions, the existing literature is still missing a mathematical tool that can describe membrane fouling in a fully quantitative manner on the basis of relevant fouling mechanisms. HYPOTHESIS In this work, a quantitative model that successfully describes cake layer formation and pore blocking is presented. We propose that the degree of pore blocking is determined by the membrane contact angle and the resulting surface coverage, while the cake layer is described by a mass balance and a cake erosion flux. VALIDATION The model is validated by comparison to experimental data from previous works (Dickhout et al. 2019; Virga et al., 2020) where membrane type, surfactant type and salinity were varied. Most input parameters could be directly taken from the experimental conditions, while four fitting parameters were required. FINDINGS The experimental data can be well described by the model which was developed to provide insight into the dominant fouling mechanisms. Moreover, where existing models usually assume that pore blocking precedes cake layer formation, here we find that cake layer formation can start and occur while the degree of pore blocking is still increasing, in line with the more dynamic nature of oil droplets filtration. These new conceptual advances in the field of colloid and interface science open up new pathways for membrane fouling understanding, prevention and control.
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Affiliation(s)
- Ettore Virga
- Membrane Science and Technology, University of Twente, Drienerlolaan 5, 7522 NB Enschede, the Netherlands; Wetsus, European Centre of Excellence for Sustainable Water Technology, Oostergoweg 9, 8911 MA Leeuwarden, the Netherlands
| | - Robert W Field
- University of Oxford, Department of Engineering Science, Parks Road, Oxford OX1 3PJ, UK
| | - P M Biesheuvel
- Wetsus, European Centre of Excellence for Sustainable Water Technology, Oostergoweg 9, 8911 MA Leeuwarden, the Netherlands
| | - Wiebe M de Vos
- Membrane Science and Technology, University of Twente, Drienerlolaan 5, 7522 NB Enschede, the Netherlands.
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Jiang J, Ye HZ, Nauta K, Van Voorhis T, Schmidt TW, Field RW. Diabatic Valence-Hole States in the C 2 Molecule: "Putting Humpty Dumpty Together Again". J Phys Chem A 2022; 126:3090-3100. [PMID: 35544770 DOI: 10.1021/acs.jpca.2c00495] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Despite the long history of spectroscopic studies of the C2 molecule, fundamental questions about its chemical bonding are still being hotly debated. The complex electronic structure of C2 is a consequence of its dense manifold of near-degenerate, low-lying electronic states. A global multi-state diabatic model is proposed here to disentangle the numerous configuration interactions that occur within four symmetry manifolds of excited states of C2 (1Πg, 3Πg, 1Σu+ , and 3Σu+ ). The key concept of our model is the existence of two "valence-hole" configurations, 2σg22σu11πu33σg2 for 1,3Πg states and 2σg22σu11πu43σg1 for 1,3Σu+ states, that are derived from 3σg ← 2σu electron promotion. The lowest-energy state from each of the four C2 symmetry species is dominated by this type of valence-hole configuration at its equilibrium internuclear separation. As a result of their large binding energy (nominal bond order of 3) and correlation with the 2s22p2 + 2s2p3 separated-atom configurations, the presence of these valence-hole configurations has a profound impact on the global electronic structure and unimolecular dynamics of C2.
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Affiliation(s)
- Jun Jiang
- Center for Accelerator Mass Spectrometry, Lawrence Livermore National Laboratory, Livermore, California 94550, United States
| | - Hong-Zhou Ye
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Klaas Nauta
- School of Chemistry, UNSW, Sydney, NSW 2052, Australia
| | - Troy Van Voorhis
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | | | - Robert W Field
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
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Field RW, Wu JJ. Permeate Flux in Ultrafiltration Processes—Understandings and Misunderstandings. Membranes 2022; 12:membranes12020187. [PMID: 35207108 PMCID: PMC8875253 DOI: 10.3390/membranes12020187] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/28/2021] [Revised: 01/20/2022] [Accepted: 01/29/2022] [Indexed: 12/10/2022]
Abstract
Concentration polarization refers to the rapid emergence of concentration gradients at a membrane/solution interface resulting from selective transfer through the membrane. It is distinguishable from fouling in at least two ways: (1) the state of the molecules involved (in solution for concentration polarization, although no longer in solution for fouling); and (2) by the timescale, normally less than a minute for concentration polarization, although generally at least two or more orders of magnitude more for fouling. Thus the phenomenon of flux decline occurring over a timescale of tens of minutes should not be attributed to concentration polarization establishing itself. This distinction and a number of questions surrounding modelling are addressed and clarified. There are two paradigmatic approaches for modelling flux, one uses the overall driving force (in which case allowance for osmotic effects are expressed as additional resistances) and the other uses the net driving force across the separating layer or fouled separating layer, although often the two are unfortunately comingled. In the discussion of flux decline models’ robust approaches for the determination of flux-time relationships, including the integral method of fouling analysis, are discussed and various concepts clarified. The final section emphases that for design purposes, pilot plant data are vital.
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Affiliation(s)
- Robert W. Field
- Faculty of Engineering and Environment, Northumbria University, Newcastle NE1 8ST, UK
- Department of Engineering Science, University of Oxford, Oxford OX1 3PJ, UK
- Correspondence: (R.W.F.); (J.J.W.)
| | - Jun Jie Wu
- Department of Engineering, Faculty of Science, Durham University, Durham DH1 3LE, UK
- Correspondence: (R.W.F.); (J.J.W.)
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Barnum TJ, Clausen G, Jiang J, Coy SL, Field RW. Long-range model of vibrational autoionization in core-nonpenetrating Rydberg states of NO. J Chem Phys 2021; 155:244303. [PMID: 34972375 DOI: 10.1063/5.0070879] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
In high orbital angular momentum (ℓ ≥ 3) Rydberg states, the centrifugal barrier hinders the close approach of the Rydberg electron to the ion-core. As a result, these core-nonpenetrating Rydberg states can be well described by a simplified model in which the Rydberg electron is only weakly perturbed by the long-range electric properties (i.e., multipole moments and polarizabilities) of the ion-core. We have used a long-range model to describe the vibrational autoionization dynamics of high-ℓ Rydberg states of nitric oxide (NO). In particular, our model explains the extensive angular momentum exchange between the ion-core and the Rydberg electron that had been previously observed in vibrational autoionization of f (ℓ = 3) Rydberg states. These results shed light on a long-standing mechanistic question around these previous observations and support a direct, vibrational mechanism of autoionization over an indirect, predissociation-mediated mechanism. In addition, our model correctly predicts newly measured total decay rates of g (ℓ = 4) Rydberg states because for ℓ ≥ 4, the non-radiative decay is dominated by autoionization rather than predissociation. We examine the predicted NO+ ion rotational state distributions generated by vibrational autoionization of g states and discuss applications of our model to achieve quantum state selection in the production of molecular ions.
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Affiliation(s)
- Timothy J Barnum
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Gloria Clausen
- Laboratorium für Physikalische Chemie, ETH Zürich, Vladimir-Prelog-Weg 2, 8093 Zürich, Switzerland
| | - Jun Jiang
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Stephen L Coy
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Robert W Field
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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Zaleski DP, Sivaramakrishnan R, Weller HR, Seifert NA, Bross DH, Ruscic B, Moore KB, Elliott SN, Copan AV, Harding LB, Klippenstein SJ, Field RW, Prozument K. Substitution Reactions in the Pyrolysis of Acetone Revealed through a Modeling, Experiment, Theory Paradigm. J Am Chem Soc 2021; 143:3124-3142. [PMID: 33615780 DOI: 10.1021/jacs.0c11677] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The development of high-fidelity mechanisms for chemically reactive systems is a challenging process that requires the compilation of rate descriptions for a large and somewhat ill-defined set of reactions. The present unified combination of modeling, experiment, and theory provides a paradigm for improving such mechanism development efforts. Here we combine broadband rotational spectroscopy with detailed chemical modeling based on rate constants obtained from automated ab initio transition state theory-based master equation calculations and high-level thermochemical parametrizations. Broadband rotational spectroscopy offers quantitative and isomer-specific detection by which branching ratios of polar reaction products may be obtained. Using this technique, we observe and characterize products arising from H atom substitution reactions in the flash pyrolysis of acetone (CH3C(O)CH3) at a nominal temperature of 1800 K. The major product observed is ketene (CH2CO). Minor products identified include acetaldehyde (CH3CHO), propyne (CH3CCH), propene (CH2CHCH3), and water (HDO). Literature mechanisms for the pyrolysis of acetone do not adequately describe the minor products. The inclusion of a variety of substitution reactions, with rate constants and thermochemistry obtained from automated ab initio kinetics predictions and Active Thermochemical Tables analyses, demonstrates an important role for such processes. The pathway to acetaldehyde is shown to be a direct result of substitution of acetone's methyl group by a free H atom, while propene formation arises from OH substitution in the enol form of acetone by a free H atom.
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Affiliation(s)
- Daniel P Zaleski
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States.,Department of Chemistry, Colgate University, Hamilton, New York 13346, United States
| | - Raghu Sivaramakrishnan
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Hailey R Weller
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States.,Department of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, Tennessee 37235, United States
| | - Nathan A Seifert
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - David H Bross
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Branko Ruscic
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Kevin B Moore
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Sarah N Elliott
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Andreas V Copan
- Emmanuel College, Natural Sciences Department, Franklin Springs, Georgia 30639, United States
| | - Lawrence B Harding
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Stephen J Klippenstein
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Robert W Field
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Kirill Prozument
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
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Nguyen TT, Adha RS, Field RW, Kim IS. Extended performance study of forward osmosis during wastewater reclamation: Quantification of fouling-based concentration polarization effects on the flux decline. J Memb Sci 2021. [DOI: 10.1016/j.memsci.2020.118755] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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Jiang J, Du Z, Liévin J, Field RW. One-colour (∼220 nm) resonance-enhanced (S 1 − S 0) multi-photon dissociation of acetylene: probe of the C 2 A1 Π u − X1 Σ +g band by frequency-modulation spectroscopy. Mol Phys 2020. [DOI: 10.1080/00268976.2020.1724340] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Affiliation(s)
- Jun Jiang
- Center for Accelerator Mass Spectrometry, Lawrence Livermore National Laboratory, Livermore, CA, USA
| | - Zhenhui Du
- State Key Laboratory of Precision Measuring Technology and Instruments, Tianjin University, Tianjin, People's Republic of China
| | - Jacques Liévin
- Service de Chimie Quantique et Photophysique, Université Libre de Bruxelles, Bruxelles, Belgium
| | - Robert W. Field
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA, USA
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Wang B, Zhang K, Field RW. Novel economical three‐stage slug bubbling process in a large‐scale flat‐sheet membrane bioreactor of double deck configuration. AIChE J 2020. [DOI: 10.1002/aic.16501] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
- Bing Wang
- Key Laboratory of Urban Pollutant ConversionInstitute of Urban Environment, Chinese Academy of Sciences Xiamen China
- College of Environmental Science and Engineering/Sino‐Canada Joint R&D Centre for Water and Environmental SafetyNankai University Tianjin China
| | - Kaisong Zhang
- Key Laboratory of Urban Pollutant ConversionInstitute of Urban Environment, Chinese Academy of Sciences Xiamen China
| | - Robert W. Field
- Department of Engineering ScienceUniversity of Oxford Oxford UK
- Faculty of Engineering and EnvironmentNorthumbria University Newcastle UK
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Affiliation(s)
- Jun Jiang
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Zhenhui Du
- State Key Laboratory of Precision Measuring Technology and Instruments, Tianjin University, Tianjin, People's Republic of China
| | - Robert W. Field
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA, USA
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Borguet E, Field RW, Hartland GV, Plummer W, Shen YR, Wang H. Tribute to Hai-Lung Dai. J Phys Chem A 2019; 123:10463-10464. [DOI: 10.1021/acs.jpca.9b09981] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Abstract
We report calculations of vibrational autoionization rates of CaF Rydberg states, based on the results of a global multi-channel quantum defect theory (MQDT) fit. Our goal is to use intuitive physical models to interpret and extend the results from the MQDT calculations and, in particular, to characterize the physical mechanisms for the interaction between the Rydberg electron and the ion-core. The calculations indicate that, among the six strongly l-mixed core-penetrating (CP) Rydberg series of CaF, the n.36 p^Π Rydberg series has the fastest Δv = 1 vibrational autoionization rate, which is at least four times larger than that for the other CP Rydberg series, in agreement with experimental results. We first demonstrate that the rotational level dependence of the vibrational autoionization rate of the n.36 p^Π series is satisfactorily explained by l-uncoupling interactions, which differ for the positive and negative Kronig symmetry levels. Next, we interpret the relative vibrational autoionization rates of all six CP Rydberg series in the context of a valence-precursor (VP) model. The VP model is a consequence of Mulliken's rule, which states that the innermost lobe of the Rydberg wavefunction remains invariant in both the nodal position and shape for members of the same Rydberg series. The electronic properties of the six VP states, which are the terminus states (lowest-n) of each of the six CP Rydberg series, are further characterized in terms of a ligand-field model, providing insight into the intimate relationship between the Rydberg electron density in the ion-core region and the vibrational autoionization rate.
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Affiliation(s)
- Jun Jiang
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Timothy J Barnum
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Stephen L Coy
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Robert W Field
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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Gunthardt CE, Wallace CJ, Hall GE, Field RW, North SW. Anomalous Intensities in the 2+1 REMPI Spectrum of the E 1Π-X 1Σ + Transition of CO. J Phys Chem A 2019; 123:2780-2788. [PMID: 30811199 DOI: 10.1021/acs.jpca.9b00109] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We report on one-color experiments near 214 nm involving the photodissociation of jet-cooled OCS to produce high rotational states (40 < J < 80) of CO (X 1Σ+, v = 0, 1) which were then ionized by 2+1 resonance-enhanced multiphoton ionization via the E 1Π state. The nominally forbidden Q-branch of the two-photon E 1Π-X 1Σ+ transition is observed with intensity comparable to the allowed R-branch. The bright character of the high- J Q-branch lines can be described quantitatively as intensity borrowing due to mixing of the E 1Π and C 1Σ+ states, using J-dependent mixing coefficients extrapolated from the observed Λ-doubling in the lower rotational levels of the E state. In addition to the significant enhancement of Q-branch intensities above the values predicted by conventional two-photon line strengths for a 1Π-1Σ+ transition, the high- J lines of the R- and P-branches appear to be suppressed in intensity by approximately a factor of 3 compared to the unperturbed low- J line strengths, most likely due to perturbations associated with a 1Σ- state. The E-state rotational term values for J < 80, v = 0 derived from the present spectra agree within our measurement and calibration uncertainties with the extrapolations based on the molecular constants previously derived from rotational levels with J < 50. The E-X transition is attractive for future application to photodissociation dynamics and rotational polarization measurements of CO photofragments, with convenient access to state-selective probing on multiple rotational branches, which exhibit different sensitivity to fragment alignment.
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Affiliation(s)
- C E Gunthardt
- Department of Chemistry , Texas A&M University , College Station , Texas 77843 , United States
| | - C J Wallace
- Department of Chemistry , Texas A&M University , College Station , Texas 77843 , United States
| | - G E Hall
- Chemistry Division , Brookhaven National Laboratory , Upton , New York 11973 , United States
| | - R W Field
- Department of Chemistry , Massachusetts Institute of Technology , Cambridge , Massachusetts 02139 , United States
| | - S W North
- Department of Chemistry , Texas A&M University , College Station , Texas 77843 , United States
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Nguyen TT, Kook S, Lee C, Field RW, Kim IS. Critical flux-based membrane fouling control of forward osmosis: Behavior, sustainability, and reversibility. J Memb Sci 2019. [DOI: 10.1016/j.memsci.2018.10.062] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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Jiang J, Saladrigas CA, Erickson TJ, Keenan CL, Field RW. Probing the predissociated levels of the S 1 state of acetylene via H-atom fluorescence and photofragment fluorescence action spectroscopy. J Chem Phys 2018; 149:174309. [PMID: 30408969 DOI: 10.1063/1.5045046] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We report two new experimental schemes to obtain rotationally resolved high-resolution spectra of predissociated S1 acetylene levels in the 47 000-47 300 cm-1 energy region (∼1200 cm-1 above the predissociation threshold). The two new detection schemes are compared to several other detection schemes (employed at similar laser power, molecular beam temperature, and number of signal averages) that have been used in our laboratory to study predissociated S1 acetylene levels, both in terms of the signal-to-noise ratio (S/N) of the resultant spectra and experimental simplicity. In the first method, H-atoms from the predissociated S1 acetylene levels are probed by two-photon laser-induced fluorescence (LIF). The H-atoms are pumped to the 3d level by the two-photon resonance transition at 205.14 nm. The resulting 3d-2p fluorescence (654.5 nm) is collected by a photomultiplier. The S/N of the H-atom fluorescence action spectrum is consistently better by ∼3× than that of the more widely used H-atom resonance-enhanced multiphoton ionization (REMPI) detection. Laser alignment is also considerably easier in H-atom fluorescence detection than H-atom REMPI detection due to the larger number-density of molecules that can be used in fluorescence vs. REMPI detection schemes. In the second method, fluorescence from electronically excited C2 and C2H photofragments of S1 acetylene is detected. In contrast to the H-atom detection schemes, the detected C2 and C2H photofragments are produced by the same UV laser as is used for the à - X ̃ acetylene excitation. As a result, laser alignment is greatly simplified for the photofragment fluorescence detection scheme, compared to both H-atom detection schemes. Using the photofragment fluorescence detection method, we are able to obtain action spectra of predissociated S1 acetylene levels with S/N ∼2× better than the HCCH REMPI detection and ∼10× better than H-atom and HCCH LIF detection schemes.
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Affiliation(s)
- Jun Jiang
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Catherine A Saladrigas
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Trevor J Erickson
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Clare L Keenan
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Robert W Field
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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Wang B, Zhang K, Field RW. Slug bubbling in flat sheet MBRs: Hydrodynamic optimization of membrane design variables through computational and experimental studies. J Memb Sci 2018. [DOI: 10.1016/j.memsci.2017.11.024] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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DeVine JA, Weichman ML, Laws B, Chang J, Babin MC, Balerdi G, Xie C, Malbon CL, Lineberger WC, Yarkony DR, Field RW, Gibson ST, Ma J, Guo H, Neumark DM. Encoding of vinylidene isomerization in its anion photoelectron spectrum. Science 2017; 358:336-339. [DOI: 10.1126/science.aao1905] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2017] [Accepted: 08/29/2017] [Indexed: 11/02/2022]
Affiliation(s)
- Jessalyn A. DeVine
- Department of Chemistry, University of California, Berkeley, CA 94720, USA
| | | | - Benjamin Laws
- Research School of Physics and Engineering, Australian National University, Canberra, ACT 2601, Australia
| | - Jing Chang
- Institute of Atomic and Molecular Physics, Sichuan University, Chengdu, Sichuan 610067, China
| | - Mark C. Babin
- Department of Chemistry, University of California, Berkeley, CA 94720, USA
| | - Garikoitz Balerdi
- Departmento de Química Física, Facultad de Ciencias Químicas, Universidad Complutense de Madrid (Unidad Asociada I+D+I CSIC), 28040 Madrid, Spain
| | - Changjian Xie
- Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, NM 87131, USA
| | | | - W. Carl Lineberger
- JILA and Department of Chemistry and Biochemistry, University of Colorado, Boulder, CO 80309, USA
| | - David R. Yarkony
- Department of Chemistry, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Robert W. Field
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Stephen T. Gibson
- Research School of Physics and Engineering, Australian National University, Canberra, ACT 2601, Australia
| | - Jianyi Ma
- Institute of Atomic and Molecular Physics, Sichuan University, Chengdu, Sichuan 610067, China
| | - Hua Guo
- Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, NM 87131, USA
| | - Daniel M. Neumark
- Department of Chemistry, University of California, Berkeley, CA 94720, USA
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
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Grimes DD, Barnum TJ, Zhou Y, Colombo AP, Field RW. Coherent laser-millimeter-wave interactions en route to coherent population transfer. J Chem Phys 2017; 147:144201. [DOI: 10.1063/1.4997624] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- David D. Grimes
- Department of Chemistry, Massaschusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Timothy J. Barnum
- Department of Chemistry, Massaschusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Yan Zhou
- JILA, National Institute of Standards and Technology, Department of Physics, University of Colorado, Boulder, Colorado 80309-0440, USA
| | - Anthony P. Colombo
- Department of Chemistry, Massaschusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Robert W. Field
- Department of Chemistry, Massaschusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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Wu X, Field RW, Wu JJ, Zhang K. Polyvinylpyrrolidone modified graphene oxide as a modifier for thin film composite forward osmosis membranes. J Memb Sci 2017. [DOI: 10.1016/j.memsci.2017.06.070] [Citation(s) in RCA: 73] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Faust C, Jones J, Huennekens J, Field RW. Experimental studies of the NaCs 12(0 +) [7 1Σ +] state: Spin-orbit and non-adiabatic interactions and quantum interference in the 12(0 +) [7 1Σ +] and 11(0 +) [5 3Π 0] emission spectra. J Chem Phys 2017; 146:104302. [PMID: 28298109 DOI: 10.1063/1.4976630] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
We present results from experimental studies of the 11(0+) and 12(0+) electronic states of the NaCs molecule. An optical-optical double resonance method is used to obtain Doppler-free excitation spectra. Selected data from the 11(0+) and 12(0+) high-lying electronic states are used to obtain Rydberg-Klein-Rees and Inverse Perturbation Approach potential energy curves. Interactions between these two electronic states are evident in the patterns observed in the bound-bound and bound-free fluorescence spectra. A model, based on two separate interaction mechanisms, is presented to describe how the wavefunctions of the two states mix. The electronic parts of the wavefunctions interact via spin-orbit coupling, while the individual rotation-vibration levels interact via a second mechanism, which is likely to be non-adiabatic coupling. A modified version of the BCONT program was used to simulate resolved fluorescence from both upper states. Parameters of the model that describe the two interaction mechanisms were varied until simulations were able to adequately reproduce experimental spectra.
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Affiliation(s)
- C Faust
- Department of Physics, Lehigh University, 16 Memorial Drive East, Bethlehem, Pennsylvania 18015, USA
| | - J Jones
- Department of Physics, Lehigh University, 16 Memorial Drive East, Bethlehem, Pennsylvania 18015, USA
| | - J Huennekens
- Department of Physics, Lehigh University, 16 Memorial Drive East, Bethlehem, Pennsylvania 18015, USADepartment of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - R W Field
- Department of Physics, Lehigh University, 16 Memorial Drive East, Bethlehem, Pennsylvania 18015, USADepartment of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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Coy SL, Grimes DD, Zhou Y, Field RW, Wong BM. Electric potential invariants and ions-in-molecules effective potentials for molecular Rydberg states. J Chem Phys 2016; 145:234301. [DOI: 10.1063/1.4968228] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Stephen L. Coy
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachussetts 02139, USA
| | - David D. Grimes
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachussetts 02139, USA
| | - Yan Zhou
- JILA, University of Colorado Boulder, 440 University Ave., Boulder, Colorado 80302, USA
| | - Robert W. Field
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachussetts 02139, USA
| | - Bryan M. Wong
- Department of Chemical and Environmental Engineering and Materials Science & Engineering Program, University of California, Riverside, California 92521, USA
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Mellau GC, Kyuberis AA, Polyansky OL, Zobov N, Field RW. Saddle point localization of molecular wavefunctions. Sci Rep 2016; 6:33068. [PMID: 27629262 PMCID: PMC5024097 DOI: 10.1038/srep33068] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2016] [Accepted: 08/21/2016] [Indexed: 12/13/2022] Open
Abstract
The quantum mechanical description of isomerization is based on bound eigenstates of the molecular potential energy surface. For the near-minimum regions there is a textbook-based relationship between the potential and eigenenergies. Here we show how the saddle point region that connects the two minima is encoded in the eigenstates of the model quartic potential and in the energy levels of the [H, C, N] potential energy surface. We model the spacing of the eigenenergies with the energy dependent classical oscillation frequency decreasing to zero at the saddle point. The eigenstates with the smallest spacing are localized at the saddle point. The analysis of the HCN ↔ HNC isomerization states shows that the eigenstates with small energy spacing relative to the effective (v1, v3, ℓ) bending potentials are highly localized in the bending coordinate at the transition state. These spectroscopically detectable states represent a chemical marker of the transition state in the eigenenergy spectrum. The method developed here provides a basis for modeling characteristic patterns in the eigenenergy spectrum of bound states.
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Affiliation(s)
- Georg Ch. Mellau
- Physikalisch-Chemisches Institut, Justus-Liebig-Universität Giessen, Heinrich-Buff-Ring 17, D-35392 Giessen, Germany
| | - Alexandra A. Kyuberis
- Institute of Applied Physics, Russian Academy of Science, 46 Uljanov Street, Nizhny Novgorod, Russia
| | - Oleg L. Polyansky
- Institute of Applied Physics, Russian Academy of Science, 46 Uljanov Street, Nizhny Novgorod, Russia
- Department of Physics and Astronomy, University College London, Gower St, London, UK
| | - Nikolai Zobov
- Institute of Applied Physics, Russian Academy of Science, 46 Uljanov Street, Nizhny Novgorod, Russia
| | - Robert W. Field
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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Jiang J, Park GB, Field RW. The rotation-vibration structure of the SO2 C̃(1)B2 state explained by a new internal coordinate force field. J Chem Phys 2016; 144:144312. [PMID: 27083726 DOI: 10.1063/1.4945621] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
A new quartic force field for the SO2 C̃(1)B2 state has been derived, based on high resolution data from S(16)O2 and S(18)O2. Included are eight b2 symmetry vibrational levels of S(16)O2 reported in the first paper of this series [G. B. Park et al., J. Chem. Phys. 144, 144311 (2016)]. Many of the experimental observables not included in the fit, such as the Franck-Condon intensities and the Coriolis-perturbed effective C rotational constants of highly anharmonic C̃ state vibrational levels, are well reproduced using our force field. Because the two stretching modes of the C̃ state are strongly coupled via Fermi-133 interaction, the vibrational structure of the C̃ state is analyzed in a Fermi-system basis set, constructed explicitly in this work via partial diagonalization of the vibrational Hamiltonian. The physical significance of the Fermi-system basis is discussed in terms of semiclassical dynamics, based on study of Fermi-resonance systems by Kellman and Xiao [J. Chem. Phys. 93, 5821 (1990)]. By diagonalizing the vibrational Hamiltonian in the Fermi-system basis, the vibrational characters of all vibrational levels can be determined unambiguously. It is shown that the bending mode cannot be treated separately from the coupled stretching modes, particularly at vibrational energies of more than 2000 cm(-1). Based on our force field, the structure of the Coriolis interactions in the C̃ state of SO2 is also discussed. We identify the origin of the alternating patterns in the effective C rotational constants of levels in the vibrational progressions of the symmetry-breaking mode, νβ (which correlates with the antisymmetric stretching mode in our assignment scheme).
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Affiliation(s)
- Jun Jiang
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - G Barratt Park
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Robert W Field
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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Affiliation(s)
- G. Barratt Park
- Institute for Physical Chemistry, University of Göttingen, Tammannstraße 6, 37077 Göttingen, Germany
- Max Planck Institute for Biophysical Chemistry, Göttingen, Am Faßberg 11, 37077 Göttingen, Germany
| | - Robert W. Field
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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Transue WJ, Velian A, Nava M, Martin-Drumel MA, Womack CC, Jiang J, Hou GL, Wang XB, McCarthy MC, Field RW, Cummins CC. A Molecular Precursor to Phosphaethyne and Its Application in Synthesis of the Aromatic 1,2,3,4-Phosphatriazolate Anion. J Am Chem Soc 2016; 138:6731-4. [DOI: 10.1021/jacs.6b03910] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Wesley J. Transue
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Alexandra Velian
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Matthew Nava
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | | | - Caroline C. Womack
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Jun Jiang
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Gao-Lei Hou
- Physical Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - Xue-Bin Wang
- Physical Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - Michael C. McCarthy
- Harvard−Smithsonian Center for Astrophysics, Cambridge, Massachusetts 02138, United States
| | - Robert W. Field
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Christopher C. Cummins
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
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Schewe HC, Zhang D, Meijer G, Field RW, Sartakov BG, Groenenboom GC, van der Avoird A, Vanhaecke N. Stark Interference of Electric and Magnetic Dipole Transitions in the A-X Band of OH. Phys Rev Lett 2016; 116:153001. [PMID: 27127965 DOI: 10.1103/physrevlett.116.153001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2016] [Indexed: 06/05/2023]
Abstract
An experimental method is demonstrated that allows determination of the ratio between the electric (E1) and magnetic (M1) transition dipole moments in the A-X band of OH, including their relative sign. Although the transition strengths differ by more than 3 orders of magnitude, the measured M1-to-E1 ratio agrees with the ratio of the ab initio calculated values to within 3%. The relative sign is found to be negative, also in agreement with theory.
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Affiliation(s)
- H Christian Schewe
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin, Germany
| | - Dongdong Zhang
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin, Germany
| | - Gerard Meijer
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin, Germany
| | - Robert W Field
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Boris G Sartakov
- General Physics Institute, RAS, Vavilov Street 38, 119991 Moscow, Russia
| | - Gerrit C Groenenboom
- Theoretical Chemistry, IMM, Radboud University, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
| | - Ad van der Avoird
- Theoretical Chemistry, IMM, Radboud University, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
| | - Nicolas Vanhaecke
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin, Germany and Laboratoire Aimé Cotton, CNRS, Université Paris-Sud, ENS Cachan, Université Paris-Saclay, 91405 Orsay, France
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Park GB, Jiang J, Field RW. The origin of unequal bond lengths in the C̃1B2
state of SO2: Signatures of high-lying potential energy surface crossings
in the low-lying vibrational structure. J Chem Phys 2016; 144:144313. [DOI: 10.1063/1.4945622] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- G. Barratt Park
- Department of Chemistry, Massachusetts Institute of
Technology, Cambridge, Massachusetts 02139,
USA
| | - Jun Jiang
- Department of Chemistry, Massachusetts Institute of
Technology, Cambridge, Massachusetts 02139,
USA
| | - Robert W. Field
- Department of Chemistry, Massachusetts Institute of
Technology, Cambridge, Massachusetts 02139,
USA
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Park GB, Jiang J, Saladrigas CA, Field RW. Observation of b2 symmetry vibrational levels of the SO2 C̃ 1B2 state: Vibrational level staggering, Coriolis interactions, and rotation-vibration constants. J Chem Phys 2016; 144:144311. [DOI: 10.1063/1.4944924] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Affiliation(s)
- G. Barratt Park
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Jun Jiang
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Catherine A. Saladrigas
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Robert W. Field
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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Liekhus-Schmaltz CE, Tenney I, Osipov T, Sanchez-Gonzalez A, Berrah N, Boll R, Bomme C, Bostedt C, Bozek JD, Carron S, Coffee R, Devin J, Erk B, Ferguson KR, Field RW, Foucar L, Frasinski LJ, Glownia JM, Gühr M, Kamalov A, Krzywinski J, Li H, Marangos JP, Martinez TJ, McFarland BK, Miyabe S, Murphy B, Natan A, Rolles D, Rudenko A, Siano M, Simpson ER, Spector L, Swiggers M, Walke D, Wang S, Weber T, Bucksbaum PH, Petrovic VS. Ultrafast isomerization initiated by X-ray core ionization. Nat Commun 2015; 6:8199. [DOI: 10.1038/ncomms9199] [Citation(s) in RCA: 79] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2014] [Accepted: 07/28/2015] [Indexed: 11/09/2022] Open
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Changala PB, Baraban JH, Merer AJ, Field RW. Probing cis-trans isomerization in the S1 state of C2H2 via H-atom action and hot band-pumped IR-UV double resonance spectroscopies. J Chem Phys 2015; 143:084310. [PMID: 26328846 DOI: 10.1063/1.4929588] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
We report novel experimental strategies that should prove instrumental in extending the vibrational and rotational assignments of the S1 state of acetylene, C2H2, in the region of the cis-trans isomerization barrier. At present, the assignments are essentially complete up to ∼500 cm(-1) below the barrier. Two difficulties arise when the assignments are continued to higher energies. One is that predissociation into C2H + H sets in roughly 1100 cm(-1) below the barrier; the resulting quenching of laser-induced fluorescence (LIF) reduces its value for recording spectra in this region. The other difficulty is that tunneling through the barrier causes a staggering in the K-rotational structure of isomerizing vibrational levels. The assignment of these levels requires data for K values up to at least 3. Given the rotational selection rule K' - ℓ('') = ± 1, such data must be obtained via excited vibrational levels of the ground state with ℓ('') > 0. In this paper, high resolution H-atom resonance-enhanced multiphoton ionization spectra are demonstrated to contain predissociated bands which are almost invisible in LIF spectra, while preliminary data using a hyperthermal pulsed nozzle show that ℓ('') = 2 states can be selectively populated in a jet, giving access to K' = 3 states in IR-UV double resonance.
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Affiliation(s)
- P Bryan Changala
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Joshua H Baraban
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Anthony J Merer
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan
| | - Robert W Field
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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Abstract
We report the observation of eigenstates that embody large-amplitude, local-bending vibrational motion in acetylene by stimulated emission pumping spectroscopy via vibrational levels of the S1 state involving excitation in the non-totally symmetric bending modes. The N(b) = 14 level, lying at 8971.69 cm(-1) (J = 0), is assigned on the basis of degeneracy due to dynamical symmetry breaking in the local-mode limit. The level pattern for the N(b) = 16 level, lying at 10 218.9 cm(-1), is consistent with expectations for increased separation of ℓ = 0 and 2 vibrational angular momentum components. Increasingly poor agreement between our observations and the predicted positions of these levels highlights the failure of currently available normal mode effective Hamiltonian models to extrapolate to regions of the potential energy surface involving large-amplitude displacement along the acetylene ⇌ vinylidene isomerization coordinate.
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Affiliation(s)
- Adam H Steeves
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - G Barratt Park
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Hans A Bechtel
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Joshua H Baraban
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Robert W Field
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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41
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Abstract
Velocity map imaging of the infrared multiphoton dissociation of vinyl chloride shows the formation of HCl in rotational levels below J = 10 that are associated with the three-center elimination pathway. The total translational energy release is observed to peak at 3-5 kcal/mol, which is consistent with the low reverse barrier predicted for the formation of HCl with vinylidene coproducts. Direct dynamics trajectory studies from the three-center transition state reproduce the observed distributions and show that the associated vinylidene is formed with only modest rotational excitation, precluding Coriolis-induced mixing among the excited vibrational levels of acetylene that would lead to distribution of vinylidene character into many vibrationally mixed acetylene vibrational levels. The results suggest that infrared multiphoton dissociation of vinyl chloride is an efficient route to synthesis of stable, cold vinylidene.
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Affiliation(s)
- Ravin Fernando
- †Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, Michigan 48202, United States
| | - Chen Qu
- ‡Department of Chemistry and Cherry L. Emerson Center for Scientific Computation, Emory University, Atlanta, Georgia 30322, United States
| | - Joel M Bowman
- ‡Department of Chemistry and Cherry L. Emerson Center for Scientific Computation, Emory University, Atlanta, Georgia 30322, United States
| | - Robert W Field
- §Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Arthur G Suits
- †Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, Michigan 48202, United States
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42
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Abeysekera C, Zack LN, Park GB, Joalland B, Oldham JM, Prozument K, Ariyasingha NM, Sims IR, Field RW, Suits AG. A chirped-pulse Fourier-transform microwave/pulsed uniform flow spectrometer. II. Performance and applications for reaction dynamics. J Chem Phys 2015; 141:214203. [PMID: 25481137 DOI: 10.1063/1.4903253] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
This second paper in a series of two reports on the performance of a new instrument for studying chemical reaction dynamics and kinetics at low temperatures. Our approach employs chirped-pulse Fourier-transform microwave (CP-FTMW) spectroscopy to probe photolysis and bimolecular reaction products that are thermalized in pulsed uniform flows. Here we detail the development and testing of a new K(a)-band CP-FTMW spectrometer in combination with the pulsed flow system described in Paper I [J. M. Oldham, C. Abeysekera, B. Joalland, L. N. Zack, K. Prozument, I. R. Sims, G. B. Park, R. W. Field, and A. G. Suits, J. Chem. Phys. 141, 154202 (2014)]. This combination delivers broadband spectra with MHz resolution and allows monitoring, on the μs timescale, of the appearance of transient reaction products. Two benchmark reactive systems are used to illustrate and characterize the performance of this new apparatus: the photodissociation of SO2 at 193 nm, for which the vibrational populations of the SO product are monitored, and the reaction between CN and C2H2, for which the HCCCN product is detected in its vibrational ground state. The results show that the combination of these two well-matched techniques, which we refer to as chirped-pulse in uniform flow, also provides insight into the vibrational and rotational relaxation kinetics of the nascent reaction products. Future directions are discussed, with an emphasis on exploring the low temperature chemistry of complex polyatomic systems.
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Affiliation(s)
- Chamara Abeysekera
- Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, Michigan 48202, USA
| | - Lindsay N Zack
- Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, Michigan 48202, USA
| | - G Barratt Park
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Baptiste Joalland
- Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, Michigan 48202, USA
| | - James M Oldham
- Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, Michigan 48202, USA
| | - Kirill Prozument
- Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, Michigan 48202, USA
| | - Nuwandi M Ariyasingha
- Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, Michigan 48202, USA
| | - Ian R Sims
- Institut de Physique de Rennes, UMR CNRS-UR1 6251, Université de Rennes 1, 263 Avenue du Général Leclerc, 35042, Rennes Cedex, France
| | - Robert W Field
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Arthur G Suits
- Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, Michigan 48202, USA
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43
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Prozument K, Barratt Park G, Shaver RG, Vasiliou AK, Oldham JM, David DE, Muenter JS, Stanton JF, Suits AG, Barney Ellison G, Field RW. Chirped-Pulse millimeter-Wave spectroscopy for dynamics and kinetics studies of pyrolysis reactions. Phys Chem Chem Phys 2015; 16:15739-15751. [PMID: 24756159 DOI: 10.1039/c3cp55352c] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A Chirped-Pulse millimeter-Wave (CPmmW) spectrometer is applied to the study of chemical reaction products that result from pyrolysis in a Chen nozzle heated to 1000-1800 K. Millimeter-wave rotational spectroscopy unambiguously determines, for each polar reaction product, the species, the conformers, relative concentrations, conversion percentage from precursor to each product, and, in some cases, vibrational state population distributions. A chirped-pulse spectrometer can, within the frequency range of a single chirp, sample spectral regions of up to ∼10 GHz and simultaneously detect many reaction products. Here we introduce a modification to the CPmmW technique in which multiple chirps of different spectral content are applied to a molecular beam pulse that contains the pyrolysis reaction products. This technique allows for controlled allocation of its sensitivity to specific molecular transitions and effectively doubles the bandwidth of the spectrometer. As an example, the pyrolysis reaction of ethyl nitrite, CH3CH2ONO, is studied, and CH3CHO, H2CO, and HNO products are simultaneously observed and quantified, exploiting the multi-chirp CPmmW technique. Rotational and vibrational temperatures of some product molecules are determined. Subsequent to supersonic expansion from the heated nozzle, acetaldehyde molecules display a rotational temperature of 4 ± 1 K. Vibrational temperatures are found to be controlled by the collisional cooling in the expansion, and to be both species- and vibrational mode-dependent. Rotational transitions of vibrationally excited formaldehyde in levels ν4, 2ν4, 3ν4, ν2, ν3, and ν6 are observed and effective vibrational temperatures for modes 2, 3, 4, and 6 are determined and discussed.
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Affiliation(s)
- Kirill Prozument
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Ave, Cambridge, MA 02139, USA. and Department of Chemistry, Wayne State University, 5101 Cass Ave, Detroit, MI 48202, USA
| | - G Barratt Park
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Ave, Cambridge, MA 02139, USA.
| | - Rachel G Shaver
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Ave, Cambridge, MA 02139, USA.
| | - AnGayle K Vasiliou
- Department of Chemistry and Biochemistry, Middlebury College, 276 Bicentennial Way, Middlebury, VT 05753, USA
| | - James M Oldham
- Department of Chemistry, Wayne State University, 5101 Cass Ave, Detroit, MI 48202, USA
| | - Donald E David
- Department of Chemistry and Biochemistry, University of Colorado at Boulder, Cristol Chemistry 58, Boulder, CO 80309, USA
| | - John S Muenter
- Department of Chemistry, University of Rochester, 120 Trustee Road, Rochester, NY 14627, USA
| | - John F Stanton
- Department of Chemistry, The University of Texas at Austin, 1 University Station A5300, Austin, TX 78712-0165, USA
| | - Arthur G Suits
- Department of Chemistry, Wayne State University, 5101 Cass Ave, Detroit, MI 48202, USA
| | - G Barney Ellison
- Department of Chemistry and Biochemistry, University of Colorado at Boulder, Cristol Chemistry 58, Boulder, CO 80309, USA
| | - Robert W Field
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Ave, Cambridge, MA 02139, USA.
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44
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Abeysekera C, Joalland B, Ariyasingha N, Zack LN, Sims IR, Field RW, Suits AG. Product Branching in the Low Temperature Reaction of CN with Propyne by Chirped-Pulse Microwave Spectroscopy in a Uniform Supersonic Flow. J Phys Chem Lett 2015; 6:1599-1604. [PMID: 26263320 DOI: 10.1021/acs.jpclett.5b00519] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
A new chirped-pulse/uniform flow (CPUF) spectrometer has been developed and used to determine product branching in a multichannel reaction. With this technique, bimolecular reactions can be initiated in a cold, thermalized, high-density molecular flow and a broadband microwave spectrum acquired for all products with rotational transitions within a chosen frequency window. In this work, the CN + CH3CCH reaction was found to yield HCN via a direct H-abstraction reaction, whereas indirect addition/elimination pathways to HCCCN, CH3CCCN, and CH2CCHCN were also probed. From these observations, quantitative branching ratios were established for all products as 12(5)%, 66(4)%, 22(6)%, and 0(8)% into HCN, HCCCN, CH3CCCN, and CH2CCHCN, respectively. The values are consistent with statistical calculations based on new ab initio results at the CBS-QB3 level of theory. This work is a demonstration of CPUF as a powerful technique for quantitatively determining the branching into polyatomic products from a bimolecular reaction.
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Affiliation(s)
- Chamara Abeysekera
- †Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, Michigan 48202, United States
| | - Baptiste Joalland
- †Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, Michigan 48202, United States
| | - Nuwandi Ariyasingha
- †Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, Michigan 48202, United States
| | - Lindsay N Zack
- †Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, Michigan 48202, United States
| | - Ian R Sims
- ‡Institut de Physique de Rennes, UMR CNRS-UR1 6251, Université de Rennes 1, 263 Avenue du Général Leclerc, 35042, Rennes CEDEX, France
| | - Robert W Field
- §Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Arthur G Suits
- †Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, Michigan 48202, United States
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45
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Park GB, Womack CC, Whitehill AR, Jiang J, Ono S, Field RW. Millimeter-wave optical double resonance schemes for rapid assignment of perturbed spectra, with applications to the C̃1B2 state of SO2. J Chem Phys 2015; 142:144201. [DOI: 10.1063/1.4916908] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- G. Barratt Park
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Caroline C. Womack
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Andrew R. Whitehill
- Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Jun Jiang
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Shuhei Ono
- Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Robert W. Field
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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46
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Womack CC, Martin-Drumel MA, Brown GG, Field RW, McCarthy MC. Observation of the simplest Criegee intermediate CH2OO in the gas-phase ozonolysis of ethylene. Sci Adv 2015; 1:e1400105. [PMID: 26601145 PMCID: PMC4643816 DOI: 10.1126/sciadv.1400105] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/14/2014] [Accepted: 02/06/2015] [Indexed: 06/05/2023]
Abstract
Ozonolysis is one of the dominant oxidation pathways for tropospheric alkenes. Although numerous studies have confirmed a 1,3-cycloaddition mechanism that generates a Criegee intermediate (CI) with form R1R2COO, no small CIs have ever been directly observed in the ozonolysis of alkenes because of their high reactivity. We present the first experimental detection of CH2OO in the gas-phase ozonolysis of ethylene, using Fourier transform microwave spectroscopy and a modified pulsed nozzle, which combines high reactant concentrations with rapid sampling and sensitive detection. Nine other product species of the O3 + C2H4 reaction were also detected, including formaldehyde, formic acid, dioxirane, and ethylene ozonide. The presence of all these species can be attributed to the unimolecular and bimolecular reactions of CH2OO, and their abundances are in qualitative agreement with published mechanisms and rate constants.
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Affiliation(s)
- Caroline C. Womack
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | | | - Gordon G. Brown
- Department of Science and Mathematics, Coker College, Hartsville, SC 29550, USA
| | - Robert W. Field
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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47
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Park GB, Steeves AH, Baraban JH, Field RW. Simplified Cartesian basis model for intrapolyad emission intensities in the bent-to-linear electronic transition of acetylene. J Phys Chem A 2015; 119:857-65. [PMID: 25625552 DOI: 10.1021/jp5113608] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The acetylene emission spectrum from the trans-bent electronically excited à state to the linear ground electronic X̃ state has attracted considerable attention because it grants Franck–Condon access to local bending vibrational levels of the X̃ state with large-amplitude motion along the acetylene ⇌ vinylidene isomerization coordinate. For emission from the ground vibrational level of the à state, there is a simplifying set of Franck–Condon propensity rules that gives rise to only one zero-order bright state per conserved vibrational polyad of the X̃ state. Unfortunately, when the upper level involves excitation in the highly admixed ungerade bending modes, ν4′ and ν6′, the simplifying Franck–Condon propensity rule breaks down--as long as the usual polar basis (with v and l quantum numbers) is used to describe the degenerate bending vibrations of the X̃ state--and the intrapolyad intensities result from complicated interference patterns between many zero-order bright states. In this article, we show that, when the degenerate bending levels are instead treated in the Cartesian two-dimensional harmonic oscillator basis (with vx and vy quantum numbers), the propensity for only one zero-order bright state (in the Cartesian basis) is restored, and the intrapolyad intensities are simple to model, as long as corrections are made for anharmonic interactions. As a result of trans ⇌ cis isomerization in the à state, intrapolyad emission patterns from overtones of ν4′ and ν6′ evolve as quanta of trans bend (ν3′) are added, so the emission intensities are not only relevant to the ground-state acetylene ⇌ vinylidene isomerization, they are also a direct reporter of isomerization in the electronically excited state.
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Affiliation(s)
- G Barratt Park
- Department of Chemistry, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States
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48
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Prozument K, Suleimanov YV, Buesser B, Oldham JM, Green WH, Suits AG, Field RW. A Signature of Roaming Dynamics in the Thermal Decomposition of Ethyl Nitrite: Chirped-Pulse Rotational Spectroscopy and Kinetic Modeling. J Phys Chem Lett 2014; 5:3641-3648. [PMID: 26278732 DOI: 10.1021/jz501758p] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Chirped-pulse (CP) Fourier transform rotational spectroscopy is uniquely suited for near-universal quantitative detection and structural characterization of mixtures that contain multiple molecular and radical species. In this work, we employ CP spectroscopy to measure product branching and extract information about the reaction mechanism, guided by kinetic modeling. Pyrolysis of ethyl nitrite, CH3CH2ONO, is studied in a Chen type flash pyrolysis reactor at temperatures of 1000-1800 K. The branching between HNO, CH2O, and CH3CHO products is measured and compared to the kinetic models generated by the Reaction Mechanism Generator software. We find that roaming CH3CH2ONO → CH3CHO + HNO plays an important role in the thermal decomposition of ethyl nitrite, with its rate, at 1000 K, comparable to that of the radical elimination channel CH3CH2ONO → CH3CH2O + NO. HNO is a signature of roaming in this system.
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Affiliation(s)
| | | | - Beat Buesser
- §IBM Research, Smarter Cities Technology Centre, Dublin 15, Ireland
| | - James M Oldham
- ∥Department of Chemistry, Wayne State University, Detroit, Michigan 48202, United States
| | | | - Arthur G Suits
- ∥Department of Chemistry, Wayne State University, Detroit, Michigan 48202, United States
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49
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Wu HY, Wang R, Field RW. Direct contact membrane distillation: An experimental and analytical investigation of the effect of membrane thickness upon transmembrane flux. J Memb Sci 2014. [DOI: 10.1016/j.memsci.2014.06.002] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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50
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Oldham JM, Abeysekera C, Joalland B, Zack LN, Prozument K, Sims IR, Park GB, Field RW, Suits AG. A chirped-pulse Fourier-transform microwave/pulsed uniform flow spectrometer. I. The low-temperature flow system. J Chem Phys 2014; 141:154202. [DOI: 10.1063/1.4897979] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- James M. Oldham
- Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, Michigan 48202, USA
| | - Chamara Abeysekera
- Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, Michigan 48202, USA
| | - Baptiste Joalland
- Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, Michigan 48202, USA
| | - Lindsay N. Zack
- Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, Michigan 48202, USA
| | - Kirill Prozument
- Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, Michigan 48202, USA
| | - Ian R. Sims
- Institut de Physique de Rennes, UMR CNRS-UR1 6251, Université de Rennes 1, 263 Avenue du Général Leclerc, 35042 Rennes Cedex, France
| | - G. Barratt Park
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Robert W. Field
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Arthur G. Suits
- Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, Michigan 48202, USA
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