1
|
Rana M, Ghosh A. Full Dynamical and Ab Initio Investigation of the Electron Transfer-Mediated Decay Mechanism of He + in the Presence of Heavier Alkali Dimers. J Phys Chem A 2024; 128:1973-1983. [PMID: 38447163 DOI: 10.1021/acs.jpca.3c07115] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/08/2024]
Abstract
We have studied the electron transfer-mediated decay (ETMD) process for the 1s ionized state of the He atom in the presence of a heavier alkali homonuclear dimer (Na2, K2, and Rb2) as well as heteronuclear dimer (LiNa, NaK, and KRb). In our computation, we have considered all the alkali dimers being in the singlet electronic ground state. The electron transfer from the alkali dimer to He (1s-1) leads to the emission of another electron from the alkali dimer into the continuum. We have investigated the impact of the distance of the He atom from the center of mass of the alkali dimer on the ETMD decay width. We also performed the Born-Oppenheimer molecular dynamics simulation to understand the impact of nuclear dynamics on the ETMD process.
Collapse
Affiliation(s)
- Meenakshi Rana
- Department of Chemistry, Ashoka University, Sonipat, Haryana 131029, India
| | - Aryya Ghosh
- Department of Chemistry, Ashoka University, Sonipat, Haryana 131029, India
| |
Collapse
|
2
|
Asmussen JD, Sishodia K, Bastian B, Abid AR, Ben Ltaief L, Pedersen HB, De S, Medina C, Pal N, Richter R, Fennel T, Krishnan S, Mudrich M. Electron energy loss and angular asymmetry induced by elastic scattering in superfluid helium nanodroplets. NANOSCALE 2023; 15:14025-14031. [PMID: 37559557 DOI: 10.1039/d3nr03295g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/11/2023]
Abstract
Helium nanodroplets are ideal model systems to unravel the complex interaction of condensed matter with ionizing radiation. Here we study the effect of purely elastic electron scattering on angular and energy distributions of photoelectrons emitted from He nanodroplets of variable size (10-109 atoms per droplets). For large droplets, photoelectrons develop a pronounced anisotropy along the incident light beam due to a shadowing effect within the droplets. In contrast, the detected photoelectron spectra are only weakly perturbed. This opens up possibilities for photoelectron spectroscopy of dopants embedded in droplets provided they are smaller than the penetration depth of the light and the trapping range of emitted electrons in liquid helium.
Collapse
Affiliation(s)
- Jakob D Asmussen
- Department of Physics and Astronomy, Aarhus University, Denmark.
| | - Keshav Sishodia
- Quantum Center of Excellence for Diamond and Emergent Materials and Department of Physics, Indian Institute of Technology Madras, India
| | - Björn Bastian
- Department of Physics and Astronomy, Aarhus University, Denmark.
| | - Abdul R Abid
- Department of Physics and Astronomy, Aarhus University, Denmark.
| | | | | | - Subhendu De
- Quantum Center of Excellence for Diamond and Emergent Materials and Department of Physics, Indian Institute of Technology Madras, India
| | | | | | | | | | - Sivarama Krishnan
- Quantum Center of Excellence for Diamond and Emergent Materials and Department of Physics, Indian Institute of Technology Madras, India
| | - Marcel Mudrich
- Department of Physics and Astronomy, Aarhus University, Denmark.
| |
Collapse
|
3
|
Ben Ltaief L, Sishodia K, Mandal S, De S, Krishnan SR, Medina C, Pal N, Richter R, Fennel T, Mudrich M. Efficient Indirect Interatomic Coulombic Decay Induced by Photoelectron Impact Excitation in Large Pure Helium Nanodroplets. PHYSICAL REVIEW LETTERS 2023; 131:023001. [PMID: 37505945 DOI: 10.1103/physrevlett.131.023001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2023] [Accepted: 06/05/2023] [Indexed: 07/30/2023]
Abstract
Ionization of matter by energetic radiation generally causes complex secondary reactions that are hard to decipher. Using large helium nanodroplets irradiated by extreme ultraviolet (XUV) photons, we show that the full chain of processes ensuing primary photoionization can be tracked in detail by means of high-resolution electron spectroscopy. We find that elastic and inelastic scattering of photoelectrons efficiently induces interatomic Coulombic decay (ICD) in the droplets. This type of indirect ICD even becomes the dominant process of electron emission in nearly the entire XUV range in large droplets with radius ≳40 nm. Indirect ICD processes induced by electron scattering likely play an important role in other condensed-phase systems exposed to ionizing radiation as well, including biological matter.
Collapse
Affiliation(s)
- L Ben Ltaief
- Department of Physics and Astronomy, Aarhus University, 8000 Aarhus C, Denmark
| | - K Sishodia
- Quantum Center of Excellence for Diamond and Emergent Materials and Department of Physics, Indian Institute of Technology Madras, Chennai 600036, India
| | - S Mandal
- Indian Institute of Science Education and Research, Pune 411008, India
| | - S De
- Quantum Center of Excellence for Diamond and Emergent Materials and Department of Physics, Indian Institute of Technology Madras, Chennai 600036, India
| | - S R Krishnan
- Quantum Center of Excellence for Diamond and Emergent Materials and Department of Physics, Indian Institute of Technology Madras, Chennai 600036, India
| | - C Medina
- Institute of Physics, University of Freiburg, 79104 Freiburg, Germany
| | - N Pal
- Elettra-Sincrotrone Trieste, 34149 Basovizza, Trieste, Italy
| | - R Richter
- Elettra-Sincrotrone Trieste, 34149 Basovizza, Trieste, Italy
| | - T Fennel
- Institute for Physics, University of Rostock, 18051 Rostock, Germany
| | - M Mudrich
- Department of Physics and Astronomy, Aarhus University, 8000 Aarhus C, Denmark
| |
Collapse
|
4
|
Bergmeister S, Ganner L, Locher J, Zappa F, Scheier P, Gruber E. Spectroscopy of helium-tagged molecular ions-Development of a novel experimental setup. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2023; 94:055105. [PMID: 37191466 DOI: 10.1063/5.0144239] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2023] [Accepted: 04/28/2023] [Indexed: 05/17/2023]
Abstract
In this contribution, we present an efficient and alternative method to the commonly used RF-multipole trap technique to produce He-tagged molecular ions at cryogenic temperatures, which are perfectly suitable for messenger spectroscopy. The seeding of dopant ions in multiply charged helium nanodroplets, in combination with a gentle extraction of the latter from the helium matrix, enables the efficient production of He-tagged ion species. With a quadrupole mass filter, a specific ion of interest is selected, merged with a laser beam, and the photoproducts are measured in a time-of-flight mass-spectrometer. The detection of the photofragment signal from a basically zero background is much more sensitive than the depletion of the same amount of signal from precursor ions, delivering high quality spectra at reduced data acquisition times. Proof-of-principle measurements of bare and He-tagged Ar-cluster ions, as well as of He-tagged C60 ions, are presented.
Collapse
Affiliation(s)
- Stefan Bergmeister
- Institute for Ion Physics and Applied Physics, University of Innsbruck, A-6020 Innsbruck, Austria
| | - Lisa Ganner
- Institute for Ion Physics and Applied Physics, University of Innsbruck, A-6020 Innsbruck, Austria
| | - Johannes Locher
- Institute for Ion Physics and Applied Physics, University of Innsbruck, A-6020 Innsbruck, Austria
| | - Fabio Zappa
- Institute for Ion Physics and Applied Physics, University of Innsbruck, A-6020 Innsbruck, Austria
| | - Paul Scheier
- Institute for Ion Physics and Applied Physics, University of Innsbruck, A-6020 Innsbruck, Austria
| | - Elisabeth Gruber
- Institute for Ion Physics and Applied Physics, University of Innsbruck, A-6020 Innsbruck, Austria
| |
Collapse
|
5
|
Albertini S, Gruber E, Zappa F, Krasnokutski S, Laimer F, Scheier P. Chemistry and physics of dopants embedded in helium droplets. MASS SPECTROMETRY REVIEWS 2022; 41:529-567. [PMID: 33993543 DOI: 10.1002/mas.21699] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Revised: 04/20/2021] [Accepted: 04/20/2021] [Indexed: 05/18/2023]
Abstract
Helium droplets represent a cold inert matrix, free of walls with outstanding properties to grow complexes and clusters at conditions that are perfect to simulate cold and dense regions of the interstellar medium. At sub-Kelvin temperatures, barrierless reactions triggered by radicals or ions have been observed and studied by optical spectroscopy and mass spectrometry. The present review summarizes developments of experimental techniques and methods and recent results they enabled.
Collapse
Affiliation(s)
- Simon Albertini
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Innsbruck, Austria
| | - Elisabeth Gruber
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Innsbruck, Austria
| | - Fabio Zappa
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Innsbruck, Austria
| | - Serge Krasnokutski
- Laboratory Astrophysics Group of the MPI for Astronomy, University of Jena, Jena, Germany
| | - Felix Laimer
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Innsbruck, Austria
| | - Paul Scheier
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Innsbruck, Austria
| |
Collapse
|
6
|
Tanyag RMP, Bacellar C, Pang W, Bernando C, Gomez LF, Jones CF, Ferguson KR, Kwok J, Anielski D, Belkacem A, Boll R, Bozek J, Carron S, Chen G, Delmas T, Englert L, Epp SW, Erk B, Foucar L, Hartmann R, Hexemer A, Huth M, Leone SR, Ma JH, Marchesini S, Neumark DM, Poon BK, Prell J, Rolles D, Rudek B, Rudenko A, Seifrid M, Swiggers M, Ullrich J, Weise F, Zwart P, Bostedt C, Gessner O, Vilesov AF. Sizes of pure and doped helium droplets from single shot x-ray imaging. J Chem Phys 2022; 156:041102. [PMID: 35105059 DOI: 10.1063/5.0080342] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Advancements in x-ray free-electron lasers on producing ultrashort, ultrabright, and coherent x-ray pulses enable single-shot imaging of fragile nanostructures, such as superfluid helium droplets. This imaging technique gives unique access to the sizes and shapes of individual droplets. In the past, such droplet characteristics have only been indirectly inferred by ensemble averaging techniques. Here, we report on the size distributions of both pure and doped droplets collected from single-shot x-ray imaging and produced from the free-jet expansion of helium through a 5 μm diameter nozzle at 20 bars and nozzle temperatures ranging from 4.2 to 9 K. This work extends the measurement of large helium nanodroplets containing 109-1011 atoms, which are shown to follow an exponential size distribution. Additionally, we demonstrate that the size distributions of the doped droplets follow those of the pure droplets at the same stagnation condition but with smaller average sizes.
Collapse
Affiliation(s)
- Rico Mayro P Tanyag
- Department of Chemistry, University of Southern California, Los Angeles, California 90089, USA
| | - Camila Bacellar
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Weiwu Pang
- Department of Computer Science, University of Southern California, Los Angeles, California 90089, USA
| | - Charles Bernando
- Department of Physics and Astronomy, University of Southern California, Los Angeles, California 90089, USA
| | - Luis F Gomez
- Department of Chemistry, University of Southern California, Los Angeles, California 90089, USA
| | - Curtis F Jones
- Department of Chemistry, University of Southern California, Los Angeles, California 90089, USA
| | - Ken R Ferguson
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - Justin Kwok
- Department of Chemical Engineering and Material Science, University of Southern California, Los Angeles, California 90089, USA
| | - Denis Anielski
- Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany
| | - Ali Belkacem
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Rebecca Boll
- Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany
| | - John Bozek
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - Sebastian Carron
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - Gang Chen
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Tjark Delmas
- Center for Free-Electron Laser Science (CFEL), Deutsches Elektronen-Synchrotron (DESY), Notkestraße 85, 22607 Hamburg, Germany
| | - Lars Englert
- Max-Planck-Institut für extraterrestrische Physik, Giessenbachstraße, 85741 Garching, Germany
| | - Sascha W Epp
- Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany
| | - Benjamin Erk
- Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany
| | - Lutz Foucar
- Max-Planck-Institut für Medizinische Forschung, Jahnstrasse 29, 69120 Heidelberg, Germany
| | | | - Alexander Hexemer
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Martin Huth
- PNSensor GmbH, Otto-Hahn-Ring 6, 81739 München, Germany
| | - Stephen R Leone
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Jonathan H Ma
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Stefano Marchesini
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Daniel M Neumark
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Billy K Poon
- Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - James Prell
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Daniel Rolles
- Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany
| | - Benedikt Rudek
- Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany
| | - Artem Rudenko
- Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany
| | - Martin Seifrid
- Department of Chemistry, University of Southern California, Los Angeles, California 90089, USA
| | - Michele Swiggers
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - Joachim Ullrich
- Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany
| | - Fabian Weise
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Petrus Zwart
- Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Christoph Bostedt
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - Oliver Gessner
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Andrey F Vilesov
- Department of Chemistry, University of Southern California, Los Angeles, California 90089, USA
| |
Collapse
|
7
|
Laimer F, Zappa F, Scheier P. Size and Velocity Distribution of Negatively Charged Helium Nanodroplets. J Phys Chem A 2021; 125:7662-7669. [PMID: 34449223 PMCID: PMC9282675 DOI: 10.1021/acs.jpca.1c05619] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Precharged helium nanodroplets can be used in doping experiments with the advantage that they are amenable to size selection with electrostatic fields, therefore adding a useful tuning parameter for dopant growth. For all these applications, the knowledge of the size distribution of charged droplets is an essential parameter, which we have so far assumed would be equivalent to that of their neutral precursors. Here, this assumption is experimentally investigated for negatively charged clusters for temperatures between 4 and 9 K at a stagnation pressure of 2 MPa. We observe a dependency of the velocity of the droplets on mass per charge, especially at the lowest temperatures of the investigated range, and values 20% lower than those known from the literature. Below 6 K, a large deviation from the literature is also found for the average droplet sizes. This information has to be taken into consideration in future experiments where large, charged droplets are sought to produce large dopant clusters. Possible origins for this deviation are discussed in the text.
Collapse
Affiliation(s)
- F Laimer
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria
| | - F Zappa
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria.,Departamento de Física-ICE, Universidade Federal de Juiz de Fora, Campus Universitário, 36036-900 Juiz de Fora, Minas Gerais, Brazil
| | - P Scheier
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria
| |
Collapse
|
8
|
Pandey R, Tran S, Zhang J, Yao Y, Kong W. Bimodal velocity and size distributions of pulsed superfluid helium droplet beams. J Chem Phys 2021; 154:134303. [PMID: 33832230 PMCID: PMC8018796 DOI: 10.1063/5.0047158] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Accepted: 03/15/2021] [Indexed: 11/14/2022] Open
Abstract
We report detailed measurements of velocities and sizes of superfluid helium droplets produced from an Even-Lavie pulse valve at stagnation pressures of 20-60 atm and temperatures between 5.7 and 18.0 K. By doping neutral droplets with Rhodamine 6G cations produced from an electrospray ionization source and detecting the positively charged droplets at two different locations along the beam path, we determine the velocities of the different groups of droplets. By subjecting the doped droplet beam to a retardation field, size distributions can then be analyzed. We discover that at stagnation temperatures above 8.0 K, a single group of droplets is observed at both locations, but at 8.0 K and below, two different groups of droplets with different velocities are detectable. The slower group, considered from fragmentation of liquid helium, cannot be deterred by the retardation voltage at 9 kV, implying an exceedingly large size. The faster group, considered from condensation of gaseous helium, has a bimodal distribution when the stagnation temperatures are below 12.3 K at 20 and 40 atm, or 16.1 K at 60 atm. We also report similar size measurements using low energy electrons for impact ionization, and this latter method can be used for facile in situ characterization of pulsed droplet beams. The mechanism of the bimodal size distribution of the condensation group and the reason for the coexistence of both the condensation and fragmentation groups remain elusive.
Collapse
Affiliation(s)
- Rahul Pandey
- Department of Chemistry, Oregon State University, Corvallis, Oregon 97331-4003, USA
| | - Steven Tran
- Department of Chemistry, Oregon State University, Corvallis, Oregon 97331-4003, USA
| | - Jie Zhang
- Department of Chemistry, Oregon State University, Corvallis, Oregon 97331-4003, USA
| | - Yuzhong Yao
- Department of Chemistry, Oregon State University, Corvallis, Oregon 97331-4003, USA
| | - Wei Kong
- Department of Chemistry, Oregon State University, Corvallis, Oregon 97331-4003, USA
| |
Collapse
|
9
|
Laimer F, Zappa F, Scheier P, Gatchell M. Multiply Charged Helium Droplet Anions. Chemistry 2021; 27:7283-7287. [PMID: 33385183 PMCID: PMC8251920 DOI: 10.1002/chem.202005004] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2020] [Revised: 12/19/2020] [Indexed: 01/20/2023]
Abstract
The detection of multiply charged helium droplet anions is reported for the first time. By ionizing droplets of superfluid helium with low energy electrons (up to 25 eV), it was possible to produce droplets containing up to five negative charges, which remain intact on the timescale of the experiment. The appearance sizes for different charge states are determined and are found to be orders of magnitude larger than for the equivalent cationic droplets, starting at 4 million He atoms for dianions. Droplets with He*− as charge carriers show signs of being metastable, but this effect is quenched by the pickup of water molecules.
Collapse
Affiliation(s)
- Felix Laimer
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25, 6020, Innsbruck, Austria
| | - Fabio Zappa
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25, 6020, Innsbruck, Austria.,Departamento de Física-ICE, Universidade Federal de Juiz de Fora, Campus Universitário, 36036-900, Juiz de Fora, MG, Brazil
| | - Paul Scheier
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25, 6020, Innsbruck, Austria
| | - Michael Gatchell
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25, 6020, Innsbruck, Austria.,Department of Physics, Stockholm University, 10691, Stockholm, Sweden
| |
Collapse
|
10
|
González-Lezana T, Echt O, Gatchell M, Bartolomei M, Campos-Martínez J, Scheier P. Solvation of ions in helium. INT REV PHYS CHEM 2020. [DOI: 10.1080/0144235x.2020.1794585] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
- Tomás González-Lezana
- Instituto de Física Fundamental, Consejo Superior de Investigaciones Científicas IFF-CSIC, Madrid, Spain
| | - Olof Echt
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Innsbruck, Austria
- Department of Physics, University of New Hampshire, Durham, NH, USA
| | - Michael Gatchell
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Innsbruck, Austria
- Department of Physics, Stockholm University, Stockholm, Sweden
| | - Massimiliano Bartolomei
- Instituto de Física Fundamental, Consejo Superior de Investigaciones Científicas IFF-CSIC, Madrid, Spain
| | - José Campos-Martínez
- Instituto de Física Fundamental, Consejo Superior de Investigaciones Científicas IFF-CSIC, Madrid, Spain
| | - Paul Scheier
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Innsbruck, Austria
| |
Collapse
|
11
|
Tanyag RMP, Feinberg AJ, O’Connell SMO, Vilesov AF. Disintegration of diminutive liquid helium jets in vacuum. J Chem Phys 2020; 152:234306. [DOI: 10.1063/5.0004503] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Affiliation(s)
- Rico Mayro P. Tanyag
- Department of Chemistry, University of Southern California, Los Angeles, California 90089, USA
| | - Alexandra J. Feinberg
- Department of Chemistry, University of Southern California, Los Angeles, California 90089, USA
| | - Sean M. O. O’Connell
- Department of Chemistry, University of Southern California, Los Angeles, California 90089, USA
| | - Andrey F. Vilesov
- Department of Chemistry, University of Southern California, Los Angeles, California 90089, USA
- Department of Physics and Astronomy, University of Southern California, Los Angeles, California 90089, USA
| |
Collapse
|
12
|
Mandal S, Gopal R, Shcherbinin M, D'Elia A, Srinivas H, Richter R, Coreno M, Bapat B, Mudrich M, Krishnan SR, Sharma V. Penning spectroscopy and structure of acetylene oligomers in He nanodroplets. Phys Chem Chem Phys 2020; 22:10149-10157. [PMID: 32347252 DOI: 10.1039/d0cp00689k] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Embedded atoms or molecules in a photoexcited He nanodroplet are well-known to be ionized through inter-atomic relaxation in a Penning process. In this work, we investigate the Penning ionization of acetylene oligomers occurring from the photoexcitation bands of He nanodroplets. In close analogy to conventional Penning electron spectroscopy by thermal atomic collisions, the n = 2 photoexcitation band plays the role of the metastable atomic 1s2s 3,1S He*. This facilitates electron spectroscopy of acetylene aggregates in the sub-Kelvin He environment, providing the following insight into their structure: the molecules in the dopant cluster are loosely bound van der Waals complexes rather than forming covalent compounds. In addition, this work reveals a Penning process stemming from the n = 4 band where charge-transfer from autoionized He in the droplets is known to be the dominant relaxation channel. This allows for excited states of the remnant dopant oligomer Penning-ions to be studied. Hence, we demonstrate Penning ionization electron spectroscopy of doped droplets as an effective technique for investigating dopant oligomers which are easily formed by attachment to the host cluster.
Collapse
Affiliation(s)
- S Mandal
- Indian Institute of Science Education and Research, Pune 411008, India
| | - R Gopal
- Tata Institute of Fundamental Research, Hyderabad 500107, India
| | | | - A D'Elia
- Department of Physics, University of Trieste, Via A. Valerio 2, 34127 Trieste, Italy
| | - H Srinivas
- Max-Planck-Institut für Kernphysik, 69117 Heidelberg, Germany
| | - R Richter
- Elettra-Sincrotrone Trieste, 34149 Basovizza, Italy
| | - M Coreno
- Elettra-Sincrotrone Trieste, 34149 Basovizza, Italy and Consiglio Nazionale delle Ricerche - Istituto di Struttura della Materia, 34149 Trieste, Italy
| | - B Bapat
- Indian Institute of Science Education and Research, Pune 411008, India
| | - M Mudrich
- Aarhus University, 8000 Aarhus C, Denmark and Indian Institute of Technology Madras, Chennai 600036, India.
| | - S R Krishnan
- Indian Institute of Technology Madras, Chennai 600036, India.
| | - V Sharma
- Indian Institute of Technology Hyderabad, Kandi 502285, India.
| |
Collapse
|
13
|
Tiefenthaler L, Ameixa J, Martini P, Albertini S, Ballauf L, Zankl M, Goulart M, Laimer F, von Haeften K, Zappa F, Scheier P. An intense source for cold cluster ions of a specific composition. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2020; 91:033315. [PMID: 32260000 DOI: 10.1063/1.5133112] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2019] [Accepted: 02/26/2020] [Indexed: 05/18/2023]
Abstract
The demand for nanoscale materials of ultra-high purity and narrow size distribution is addressed. Clusters of Au, C60, H2O, and serine are produced inside helium nanodroplets using a combination of ionization, mass filtering, collisions with atomic or molecular vapor, and electrostatic extraction, in a specific and novel sequence. The helium droplets are produced in an expansion of cold helium gas through a nozzle into vacuum. The droplets are ionized by electron bombardment and subjected to a mass filter. The ionic and mass-selected helium droplets are then guided through a vacuum chamber filled with atomic or molecular vapor where they collide and "pick up" the vapor. The dopants then agglomerate inside the helium droplets around charge centers to singly charged clusters. Evaporation of the helium droplets is induced by collisions in a helium-filled radio frequency (RF)-hexapole, which liberates the cluster ions from the host droplets. The clusters are analyzed with a time-of-flight mass spectrometer. It is demonstrated that using this sequence, the size distribution of the dopant cluster ions is distinctly narrower compared to ionization after pickup. Likewise, the ion cluster beam is more intense. The mass spectra show, as well, that ion clusters of the dopants can be produced with only few helium atoms attached, which will be important for messenger spectroscopy. All these findings are important for the scientific research of clusters and nanoscale materials in general.
Collapse
Affiliation(s)
- L Tiefenthaler
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria
| | - J Ameixa
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria
| | - P Martini
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria
| | - S Albertini
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria
| | - L Ballauf
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria
| | - M Zankl
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria
| | - M Goulart
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria
| | - F Laimer
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria
| | - K von Haeften
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria
| | - F Zappa
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria
| | - P Scheier
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria
| |
Collapse
|
14
|
Mahmoodi-Darian M, Martini P, Tiefenthaler L, Kočišek J, Scheier P, Echt O. Solvation of Silver Ions in Noble Gases He, Ne, Ar, Kr, and Xe. J Phys Chem A 2019; 123:10426-10436. [PMID: 31725298 DOI: 10.1021/acs.jpca.9b09496] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We use a novel technique to solvate silver cations in small clusters of noble gases. The technique involves the formation of large, superfluid helium nanodroplets that are subsequently electron ionized, mass-selected by deflection in an electric field, and doped with silver atoms and noble gases (Ng) in pickup cells. Excess helium is then stripped from the doped nanodroplets by multiple collisions with helium gas at room temperature, producing cluster ions that contain no more than a few dozen noble gas atoms and just a few (or no) silver atoms. Under gentle stripping conditions, helium atoms remain attached to the cluster ions, demonstrating their low vibrational temperature. Under harsher stripping conditions, some of the heavier noble gas atoms will be evaporated as well, thus enriching stable clusters of NgnAgm+ at the expense of less stable ones. This results in local anomalies in the cluster ion abundance, which is measured in a high-resolution time-of-flight mass spectrometer. On the basis of these data, we identify specific "magic" sizes n of particularly stable ions. There is no evidence, however, for enhanced stability of Ng2Ag+, in contrast to the high stability of Ng2Au+ that derives from the covalent nature of the bond for heavy noble gases. "Magic" sizes are also identified for Ag2+ dimer ions complexed with He or Kr. Structural models will be tentatively proposed. A sequence of magic numbers n = 12, 32, and 44, indicative of three concentric solvation shells of icosahedral symmetry, is observed for HenH2O+.
Collapse
Affiliation(s)
| | - Paul Martini
- Institut für Ionenphysik und Angewandte Physik , Universität Innsbruck , Innsbruck A-6020 , Austria
| | - Lukas Tiefenthaler
- Institut für Ionenphysik und Angewandte Physik , Universität Innsbruck , Innsbruck A-6020 , Austria
| | - Jaroslav Kočišek
- Institut für Ionenphysik und Angewandte Physik , Universität Innsbruck , Innsbruck A-6020 , Austria.,J. Heyrovský Institute of Physical Chemistry of the CAS , Prague 18223 , Czech Republic
| | - Paul Scheier
- Institut für Ionenphysik und Angewandte Physik , Universität Innsbruck , Innsbruck A-6020 , Austria
| | - Olof Echt
- Institut für Ionenphysik und Angewandte Physik , Universität Innsbruck , Innsbruck A-6020 , Austria.,Department of Physics , University of New Hampshire , Durham , New Hampshire 03824 , United States
| |
Collapse
|
15
|
Laimer F, Kranabetter L, Tiefenthaler L, Albertini S, Zappa F, Ellis AM, Gatchell M, Scheier P. Highly Charged Droplets of Superfluid Helium. PHYSICAL REVIEW LETTERS 2019; 123:165301. [PMID: 31702350 DOI: 10.1103/physrevlett.123.165301] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2019] [Revised: 08/26/2019] [Indexed: 05/18/2023]
Abstract
We report on the production and study of stable, highly charged droplets of superfluid helium. Using a novel experimental setup we produce neutral beams of liquid helium nanodroplets containing millions of atoms or more that can be ionized by electron impact, mass-per-charge selected, and ionized a second time before being analyzed. Droplets containing up to 55 net positive charges are identified and the appearance sizes of multiply charge droplets are determined as a function of the charge state. We show that the droplets are stable on the millisecond timescale of the experiment and decay through the loss of small charged clusters, not through symmetric Coulomb explosions.
Collapse
Affiliation(s)
- Felix Laimer
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria
| | - Lorenz Kranabetter
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria
| | - Lukas Tiefenthaler
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria
| | - Simon Albertini
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria
| | - Fabio Zappa
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria
- Departamento de Física-ICE, Universidade Federal de Juiz de Fora, Campus Universitário, 36036-900, Juiz de Fora, MG, Brazil
| | - Andrew M Ellis
- Department of Chemistry, University of Leicester, University Road, Leicester, LE1 7RH, United Kingdom
| | - Michael Gatchell
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria
- Department of Physics, Stockholm University, 106 91 Stockholm, Sweden
| | - Paul Scheier
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria
| |
Collapse
|
16
|
Császár AG, Szidarovszky T, Asvany O, Schlemmer S. Fingerprints of microscopic superfluidity in HHe n+ clusters. Mol Phys 2019. [DOI: 10.1080/00268976.2019.1585984] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Affiliation(s)
- Attila G. Császár
- Laboratory of Molecular Structure and Dynamics, Institute of Chemistry, ELTE Eötvös Loránd University and MTA-ELTE Complex Chemical Systems Research Group, Budapest, Hungary
| | - Tamás Szidarovszky
- Laboratory of Molecular Structure and Dynamics, Institute of Chemistry, ELTE Eötvös Loránd University and MTA-ELTE Complex Chemical Systems Research Group, Budapest, Hungary
| | - Oskar Asvany
- I. Physikalisches Institut, Universität zu Köln, Köln, Germany
| | | |
Collapse
|
17
|
Shcherbinin M, Westergaard FV, Hanif M, Krishnan SR, LaForge AC, Richter R, Pfeifer T, Mudrich M. Inelastic scattering of photoelectrons from He nanodroplets. J Chem Phys 2019; 150:044304. [PMID: 30709284 DOI: 10.1063/1.5074130] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
We present a detailed study of inelastic energy-loss collisions of photoelectrons emitted from He nanodroplets by tunable extreme ultraviolet (XUV) radiation. Using coincidence imaging detection of electrons and ions, we probe the lowest He droplet excited states up to the electron impact ionization threshold. We find significant signal contributions from photoelectrons emitted from free He atoms accompanying the He nanodroplet beam. Furthermore, signal contributions from photoionization and electron impact excitation/ionization occurring in pairs of nearest-neighbor atoms in the He droplets are detected. This work highlights the importance of inelastic electron scattering in the interaction of nanoparticles with XUV radiation.
Collapse
Affiliation(s)
- M Shcherbinin
- Department of Physics and Astronomy, Aarhus University, 8000 Aarhus C, Denmark
| | - F Vad Westergaard
- Department of Physics and Astronomy, Aarhus University, 8000 Aarhus C, Denmark
| | - M Hanif
- Department of Physics and Astronomy, Aarhus University, 8000 Aarhus C, Denmark
| | - S R Krishnan
- Department of Physics, Indian Institute of Technology, Madras, Chennai 600 036, India
| | - A C LaForge
- Department of Physics, University of Connecticut, Storrs, Connecticut 06269, USA
| | - R Richter
- Elettra-Sincrotrone Trieste, 34149 Basovizza, Trieste, Italy
| | - T Pfeifer
- Max-Planck-Institut für Kernphysik, 69117 Heidelberg, Germany
| | - M Mudrich
- Department of Physics and Astronomy, Aarhus University, 8000 Aarhus C, Denmark
| |
Collapse
|
18
|
Langbehn B, Sander K, Ovcharenko Y, Peltz C, Clark A, Coreno M, Cucini R, Drabbels M, Finetti P, Di Fraia M, Giannessi L, Grazioli C, Iablonskyi D, LaForge AC, Nishiyama T, Oliver Álvarez de Lara V, Piseri P, Plekan O, Ueda K, Zimmermann J, Prince KC, Stienkemeier F, Callegari C, Fennel T, Rupp D, Möller T. Three-Dimensional Shapes of Spinning Helium Nanodroplets. PHYSICAL REVIEW LETTERS 2018; 121:255301. [PMID: 30608832 DOI: 10.1103/physrevlett.121.255301] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2018] [Revised: 10/24/2018] [Indexed: 05/12/2023]
Abstract
A significant fraction of superfluid helium nanodroplets produced in a free-jet expansion has been observed to gain high angular momentum resulting in large centrifugal deformation. We measured single-shot diffraction patterns of individual rotating helium nanodroplets up to large scattering angles using intense extreme ultraviolet light pulses from the FERMI free-electron laser. Distinct asymmetric features in the wide-angle diffraction patterns enable the unique and systematic identification of the three-dimensional droplet shapes. The analysis of a large data set allows us to follow the evolution from axisymmetric oblate to triaxial prolate and two-lobed droplets. We find that the shapes of spinning superfluid helium droplets exhibit the same stages as classical rotating droplets while the previously reported metastable, oblate shapes of quantum droplets are not observed. Our three-dimensional analysis represents a valuable landmark for clarifying the interrelation between morphology and superfluidity on the nanometer scale.
Collapse
Affiliation(s)
- Bruno Langbehn
- Institut für Optik und Atomare Physik, Technische Universität Berlin, 10623 Berlin, Germany
| | - Katharina Sander
- Institut für Physik, Universität Rostock, 18051 Rostock, Germany
| | - Yevheniy Ovcharenko
- Institut für Optik und Atomare Physik, Technische Universität Berlin, 10623 Berlin, Germany
- European XFEL GmbH, 22869 Schenefeld, Germany
| | - Christian Peltz
- Institut für Physik, Universität Rostock, 18051 Rostock, Germany
| | - Andrew Clark
- Laboratory of Molecular Nanodynamics, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - Marcello Coreno
- ISM-CNR, Istituto di Struttura della Materia, LD2 Unit, 34149 Trieste, Italy
| | | | - Marcel Drabbels
- Laboratory of Molecular Nanodynamics, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - Paola Finetti
- Elettra-Sincrotrone Trieste S.C.p.A., 34149 Trieste, Italy
| | - Michele Di Fraia
- ISM-CNR, Istituto di Struttura della Materia, LD2 Unit, 34149 Trieste, Italy
- Elettra-Sincrotrone Trieste S.C.p.A., 34149 Trieste, Italy
| | - Luca Giannessi
- Elettra-Sincrotrone Trieste S.C.p.A., 34149 Trieste, Italy
| | - Cesare Grazioli
- ISM-CNR, Istituto di Struttura della Materia, LD2 Unit, 34149 Trieste, Italy
| | - Denys Iablonskyi
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577, Japan
| | - Aaron C LaForge
- Physikalisches Institut, Universität Freiburg, 79104 Freiburg, Germany
| | - Toshiyuki Nishiyama
- Division of Physics and Astronomy, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
| | | | - Paolo Piseri
- CIMAINA and Dipartimento di Fisica, Università degli Studi di Milano, 20133 Milano, Italy
| | - Oksana Plekan
- Elettra-Sincrotrone Trieste S.C.p.A., 34149 Trieste, Italy
| | - Kiyoshi Ueda
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577, Japan
| | - Julian Zimmermann
- Institut für Optik und Atomare Physik, Technische Universität Berlin, 10623 Berlin, Germany
- Max-Born-Institut fur Nichtlineare Optik und Kurzzeitspektroskopie, 12489 Berlin, Germany
| | - Kevin C Prince
- Elettra-Sincrotrone Trieste S.C.p.A., 34149 Trieste, Italy
- Department of Chemistry and Biotechnology, Swinburne University of Technology, Victoria 3122, Australia
| | | | - Carlo Callegari
- ISM-CNR, Istituto di Struttura della Materia, LD2 Unit, 34149 Trieste, Italy
- Elettra-Sincrotrone Trieste S.C.p.A., 34149 Trieste, Italy
| | - Thomas Fennel
- Institut für Physik, Universität Rostock, 18051 Rostock, Germany
- Max-Born-Institut fur Nichtlineare Optik und Kurzzeitspektroskopie, 12489 Berlin, Germany
| | - Daniela Rupp
- Institut für Optik und Atomare Physik, Technische Universität Berlin, 10623 Berlin, Germany
- Max-Born-Institut fur Nichtlineare Optik und Kurzzeitspektroskopie, 12489 Berlin, Germany
| | - Thomas Möller
- Institut für Optik und Atomare Physik, Technische Universität Berlin, 10623 Berlin, Germany
| |
Collapse
|
19
|
Shcherbinin M, LaForge AC, Hanif M, Richter R, Mudrich M. Penning Ionization of Acene Molecules by Helium Nanodroplets. J Phys Chem A 2018; 122:1855-1860. [DOI: 10.1021/acs.jpca.7b12506] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- M. Shcherbinin
- Department
of Physics and Astronomy, Aarhus University, 8000 Aarhus C, Denmark
| | - A. C. LaForge
- Physikalisches
Institut, Universität Freiburg, 79104 Freiburg, Germany
| | - M. Hanif
- Department
of Physics and Astronomy, Aarhus University, 8000 Aarhus C, Denmark
| | - R. Richter
- Elettra Sincrotrone, 34149 Basovizza, Trieste, Italy
| | - M. Mudrich
- Department
of Physics and Astronomy, Aarhus University, 8000 Aarhus C, Denmark
| |
Collapse
|
20
|
|
21
|
Fine J, Verma D, Jones CF, Wittig C, Vilesov AF. Formation of He4+via electron impact of helium droplets. J Chem Phys 2018; 148:044302. [DOI: 10.1063/1.5001715] [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)
- Jordan Fine
- Department of Chemistry, University of Southern California, Los Angeles, California 90089, USA
| | - Deepak Verma
- Department of Chemistry, University of Southern California, Los Angeles, California 90089, USA
| | - Curtis F. Jones
- Department of Chemistry, University of Southern California, Los Angeles, California 90089, USA
| | - Curt Wittig
- Department of Chemistry, University of Southern California, Los Angeles, California 90089, USA
| | - Andrey F. Vilesov
- Department of Chemistry, University of Southern California, Los Angeles, California 90089, USA
| |
Collapse
|
22
|
Renzler M, Kranabetter L, Barwa E, Grubwieser L, Scheier P, Ellis AM. Resonant electron attachment to mixed hydrogen/oxygen and deuterium/oxygen clusters. J Chem Phys 2017; 147:194301. [DOI: 10.1063/1.5003428] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Affiliation(s)
- Michael Renzler
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria
- Institut für Mechatronik, Universität Innsbruck, Technikstr. 13, A-6020 Innsbruck, Austria
| | - Lorenz Kranabetter
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria
| | - Erik Barwa
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria
| | - Lukas Grubwieser
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria
| | - Paul Scheier
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria
| | - Andrew M. Ellis
- Department of Chemistry, University of Leicester, University Road, Leicester LE1 7RH, United Kingdom
| |
Collapse
|
23
|
Loginov E, Gomez LF, Sartakov BG, Vilesov AF. Formation of Core-Shell Ethane-Silver Clusters in He Droplets. J Phys Chem A 2017; 121:5978-5982. [PMID: 28723086 DOI: 10.1021/acs.jpca.7b05136] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Ethane core-silver shell clusters consisting of several thousand particles have been assembled in helium droplets upon capture of ethane molecules followed by Ag atoms. The composite clusters were studied via infrared laser spectroscopy in the range of the C-H stretching vibrations of ethane. The spectra reveal a splitting of the vibrational bands, which is ascribed to interaction with Ag. A rigorous analysis of band intensities for a varying number of trapped ethane molecules and Ag atoms indicates that the composite clusters consist of a core of ethane that is covered by relatively small Ag clusters. This metastable structure is stabilized due to fast dissipation in superfluid helium droplets of the cohesion energy of the clusters.
Collapse
Affiliation(s)
- Evgeny Loginov
- Department of Chemistry, University of Southern California , Los Angeles, California 90089, United States
| | - Luis F Gomez
- Department of Chemistry, University of Southern California , Los Angeles, California 90089, United States
| | - Boris G Sartakov
- Prokhorov General Physics Institute, Russian Academy of Sciences , Vavilov Street, 38, 119991 Moscow, Russia
| | - Andrey F Vilesov
- Department of Chemistry, University of Southern California , Los Angeles, California 90089, United States
| |
Collapse
|
24
|
Renzler M, Kuhn M, Mauracher A, Lindinger A, Scheier P, Ellis AM. Anionic Hydrogen Cluster Ions as a New Form of Condensed Hydrogen. PHYSICAL REVIEW LETTERS 2016; 117:273001. [PMID: 28084770 DOI: 10.1103/physrevlett.117.273001] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2016] [Indexed: 06/06/2023]
Abstract
We report the first experimental observation of negatively charged hydrogen and deuterium cluster ions, H_{n}^{-} and D_{n}^{-}, where n≥5. These anions are formed by an electron addition to liquid helium nanodroplets doped with molecular hydrogen or deuterium. The ions are stable for at least the lifetime of the experiment, which is several tens of microseconds. Only anions with odd values of n are detected, and some specific ions show anomalously high abundances. The sizes of these "magic number" ions suggest an icosahedral framework of H_{2} (D_{2}) molecules in solvent shells around a central H^{-} (D^{-}) ion. The first three shells, which contain a total of 44 H_{2} or D_{2} molecules, appear to be solidlike, but thereafter a more liquidlike arrangement of the H_{2} (D_{2}) molecules is adopted.
Collapse
Affiliation(s)
- Michael Renzler
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstrasse 25, A-6020 Innsbruck, Austria
| | - Martin Kuhn
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstrasse 25, A-6020 Innsbruck, Austria
| | - Andreas Mauracher
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstrasse 25, A-6020 Innsbruck, Austria
| | - Albrecht Lindinger
- Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
| | - Paul Scheier
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstrasse 25, A-6020 Innsbruck, Austria
| | - Andrew M Ellis
- Department of Chemistry, University of Leicester, University Road, Leicester LE1 7RH, United Kingdom
| |
Collapse
|
25
|
Gomez LF, O’Connell SMO, Jones CF, Kwok J, Vilesov AF. Laser-induced reconstruction of Ag clusters in helium droplets. J Chem Phys 2016. [DOI: 10.1063/1.4962362] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Luis F. Gomez
- Department of Chemistry, University of Southern California, Los Angeles, California 90089, USA
| | - Sean M. O. O’Connell
- Department of Chemistry, University of Southern California, Los Angeles, California 90089, USA
| | - Curtis F. Jones
- Department of Chemistry, University of Southern California, Los Angeles, California 90089, USA
| | - Justin Kwok
- Department of Chemistry, University of Southern California, Los Angeles, California 90089, USA
| | - Andrey F. Vilesov
- Department of Chemistry, University of Southern California, Los Angeles, California 90089, USA
| |
Collapse
|
26
|
Rodríguez-Cantano R, González-Lezana T, Villarreal P. Path integral Monte Carlo investigations on doped helium clusters. INT REV PHYS CHEM 2016. [DOI: 10.1080/0144235x.2015.1132595] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
|
27
|
Thaler P, Volk A, Knez D, Lackner F, Haberfehlner G, Steurer J, Schnedlitz M, Ernst WE. Synthesis of nanoparticles in helium droplets-A characterization comparing mass-spectra and electron microscopy data. J Chem Phys 2016; 143:134201. [PMID: 26450307 DOI: 10.1063/1.4932182] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Micrometer sized helium droplets provide an extraordinary environment for the growth of nanoparticles. The method promises great potential for the preparation of core-shell particles as well as one-dimensional nanostructures, which agglomerate along quantum vortices, without involving solvents, ligands, or additives. Using a new apparatus, which enables us to record mass spectra of heavy dopant clusters (>10(4) amu) and to produce samples for transmission electron microscopy simultaneously, we synthesize bare and bimetallic nanoparticles consisting of various materials (Au, Ni, Cr, and Ag). We present a systematical study of the growth process of clusters and nanoparticles inside the helium droplets, which can be described with a simple theoretical model.
Collapse
Affiliation(s)
- Philipp Thaler
- Institute of Experimental Physics, Graz University of Technology, Petersgasse 16, A-8010 Graz, Austria
| | - Alexander Volk
- Institute of Experimental Physics, Graz University of Technology, Petersgasse 16, A-8010 Graz, Austria
| | - Daniel Knez
- Institute for Electron Microscopy and Nanoanalysis & Graz Centre for Electron Microscopy, TU Graz, Steyrergasse 17, A-8010 Graz, Austria
| | - Florian Lackner
- Institute of Experimental Physics, Graz University of Technology, Petersgasse 16, A-8010 Graz, Austria
| | - Georg Haberfehlner
- Institute for Electron Microscopy and Nanoanalysis & Graz Centre for Electron Microscopy, TU Graz, Steyrergasse 17, A-8010 Graz, Austria
| | - Johannes Steurer
- Institute of Experimental Physics, Graz University of Technology, Petersgasse 16, A-8010 Graz, Austria
| | - Martin Schnedlitz
- Institute of Experimental Physics, Graz University of Technology, Petersgasse 16, A-8010 Graz, Austria
| | - Wolfgang E Ernst
- Institute of Experimental Physics, Graz University of Technology, Petersgasse 16, A-8010 Graz, Austria
| |
Collapse
|
28
|
Villarreal P, Rodríguez-Cantano R, González-Lezana T, Prosmiti R, Delgado-Barrio G, Gianturco FA. Quantum Features of Anionic Species He*⁻ and He₂*⁻ in Small He(N) Clusters. J Phys Chem A 2015; 119:11574-82. [PMID: 26517581 DOI: 10.1021/acs.jpca.5b08470] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We present variational calculations on systems containing a few boson helium atoms attached to electronically excited atomic and molecular helium anions He*⁻ and He₂*⁻ and characterize their structures and energetics. Previously reported high-level ab initio results [Huber, S. E.; Mauracher, A. Mol. Phys. 2014, 112, 794] to describe the interactions between excited (metastable) anions and a neutral He atom have been employed. For the case of the atomic species He*⁻, the corresponding interaction with He suggests large anharmonicity effects due to the presence of a deep well of ∼17,500 cm⁻¹ at short distances, together with a more external shallow secondary well of ∼4 cm⁻¹, both supporting bound levels. Moreover, when a sum of pairwise interactions is assumed to describe the full PES corresponding to the presence of several neutral He atoms, geometrical constraints already predict the complete solvation of the anionic impurity by six helium atoms, giving rise to a bipyramidal structure. In turn, for the anisotropic weak interaction He-He₂*⁻, where the anionic dimer is considered as a rigid rotor, the obtained structures show the tendency of the helium atoms to pack themselves together and largely far away from the dopant, thereby confirming the heliophobic character of He₂*⁻.
Collapse
Affiliation(s)
- Pablo Villarreal
- Instituto de Fı́sica Fundamental, IFF-CSIC , Serrano 123, 28006 Madrid, Spain
| | | | | | - Rita Prosmiti
- Instituto de Fı́sica Fundamental, IFF-CSIC , Serrano 123, 28006 Madrid, Spain
| | | | - Franco A Gianturco
- Institute of Ion Physics, The University of Innsbruck , Technikerstrasse 25, 6020 Innsbruck, Austria.,Scuola Normale Superiore ,Piazza dei Cavalieri 7, 56126 Pisa, Italy
| |
Collapse
|
29
|
Postler J, Renzler M, Kaiser A, Huber S, Probst M, Scheier P, Ellis AM. Electron-Induced Chemistry of Cobalt Tricarbonyl Nitrosyl (Co(CO) 3NO) in Liquid Helium Nanodroplets. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2015; 119:20917-20922. [PMID: 26401190 PMCID: PMC4568542 DOI: 10.1021/acs.jpcc.5b05260] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/03/2015] [Revised: 08/11/2015] [Indexed: 06/05/2023]
Abstract
Electron addition to cobalt tricarbonyl nitrosyl (Co(CO3NO) and its clusters has been explored in helium nanodroplets. Anions were formed by adding electrons with controlled energies, and reaction products were identified by mass spectrometry. Dissociative electron attachment (DEA) to the Co(CO)3NO monomer gave reaction products similar to those reported in earlier gas phase experiments. However, loss of NO was more prevalent than loss of CO, in marked contrast to the gas phase. Since the Co-N bond is significantly stronger than the Co-C bond, this preference for NO loss must be driven by selective reaction dynamics at low temperature. For [Co(CO)3NO] N clusters, the DEA chemistry is similar to that of the monomer, but the anion yields as a function of electron energy show large differences, with the relatively sharp resonances of the monomer being replaced by broad profiles peaking at much higher electron energies. A third experiment involved DEA of Co(CO)3NO on a C60 molecule in an attempt to simulate the effect of a surface. Once again, broad ion yield curves are seen, but CO loss now becomes the most probable reaction channel. The implication of these findings for understanding focused electron beam induced deposition of cobalt is described.
Collapse
Affiliation(s)
- Johannes Postler
- Institut
für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria
| | - Michael Renzler
- Institut
für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria
| | - Alexander Kaiser
- Institut
für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria
| | - Stefan
E. Huber
- Institut
für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria
| | - Michael Probst
- Institut
für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria
| | - Paul Scheier
- Institut
für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria
| | - Andrew M. Ellis
- Department
of Chemistry, University of Leicester, University Road, Leicester, LE1 7RH, U. K.
| |
Collapse
|
30
|
Renzler M, Daxner M, Weinberger N, Denifl S, Scheier P, Echt O. On subthreshold ionization of helium droplets, ejection of He(+), and the role of anions. Phys Chem Chem Phys 2015; 16:22466-70. [PMID: 25230760 DOI: 10.1039/c4cp03236e] [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
The mechanism of ionization of helium droplets has been investigated in numerous reports but one observation has not found a satisfactory explanation: How are He(+) ions formed and ejected from undoped droplets at electron energies below the ionization threshold of the free atom? Does this path exist at all? A measurement of the ion yields of He(+) and He2(+) as a function of electron energy, electron emission current, and droplet size reveals that metastable He*(-) anions play a crucial role in the formation of free He(+) at subthreshold energies. The proposed model is testable.
Collapse
Affiliation(s)
- Michael Renzler
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstraße 25, A-6020 Innsbruck, Austria.
| | | | | | | | | | | |
Collapse
|
31
|
Harnisch M, Weinberger N, Denifl S, Scheier P, Echt O. Helium Droplets Doped with Sulfur and C 60. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2015; 119:10919-10924. [PMID: 26045732 PMCID: PMC4450369 DOI: 10.1021/jp510870x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2014] [Revised: 12/23/2014] [Indexed: 05/29/2023]
Abstract
Clusters of sulfur are grown by passing superfluid helium nanodroplets through a pickup cell filled with sulfur vapor. In some experiments the droplets are codoped with C60. The doped droplets are collided with energetic electrons and the abundance distributions of positively and negatively charged cluster ions are recorded. We report, specifically, distributions of S m+, S m-, and C60S m- containing up to 41 sulfur atoms. We also observe complexes of sulfur cluster anions with helium; distributions are presented for He n S m- with n ≤ 31 and m ≤ 3. The similarity between anionic and cationic C60S m± spectra is in striking contrast to the large differences between spectra of S m+ and S m-.
Collapse
Affiliation(s)
- Martina Harnisch
- Institut
für Ionenphysik und Angewandte Physik, University of Innsbruck, Technikerstrasse 25, A-6020 Innsbruck, Austria
| | - Nikolaus Weinberger
- Institut
für Ionenphysik und Angewandte Physik, University of Innsbruck, Technikerstrasse 25, A-6020 Innsbruck, Austria
| | - Stephan Denifl
- Institut
für Ionenphysik und Angewandte Physik, University of Innsbruck, Technikerstrasse 25, A-6020 Innsbruck, Austria
| | - Paul Scheier
- Institut
für Ionenphysik und Angewandte Physik, University of Innsbruck, Technikerstrasse 25, A-6020 Innsbruck, Austria
| | - Olof Echt
- Institut
für Ionenphysik und Angewandte Physik, University of Innsbruck, Technikerstrasse 25, A-6020 Innsbruck, Austria
- Department
of Physics, University of New Hampshire, Durham, New Hampshire 03824, United States
| |
Collapse
|
32
|
Rodríguez-Cantano R, González-Lezana T, Villarreal P, Gianturco FA. A configurational study of helium clusters doped with He∗− and He2∗−. J Chem Phys 2015; 142:104303. [DOI: 10.1063/1.4913958] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Affiliation(s)
| | | | - Pablo Villarreal
- Instituto de Física Fundamental, CSIC, Serrano 123, 28006 Madrid, Spain
| | - Franco A. Gianturco
- Institute of Ion Physics, The University of Innsbruck, Technikerstr. 25, 6020 Innsbruck, Austriaand Scuola Normale Superiore, Piazza dei Cavalieri 7, 56126 Pisa, Italy
| |
Collapse
|
33
|
Calvo F. Coating Polycyclic Aromatic Hydrocarbon Cations with Helium Clusters: Snowballs and Slush. J Phys Chem A 2014; 119:5959-70. [DOI: 10.1021/jp510799h] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Affiliation(s)
- Florent Calvo
- University of Grenoble Alpes, LIPHY, F-38000 Grenoble, France and
- CNRS, LIPHY, F-38000 Grenoble, France
| |
Collapse
|
34
|
Mauracher A, Daxner M, Postler J, Huber S, Denifl S, Scheier P, Toennies JP. Detection of Negative Charge Carriers in Superfluid Helium Droplets: The Metastable Anions He *- and He 2*-. J Phys Chem Lett 2014; 5:2444-2449. [PMID: 25068008 PMCID: PMC4106244 DOI: 10.1021/jz500917z] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2014] [Accepted: 06/20/2014] [Indexed: 05/13/2023]
Abstract
Helium droplets provide the possibility to study phenomena at the very low temperatures at which quantum mechanical effects are more pronounced and fewer quantum states have significant occupation probabilities. Understanding the migration of either positive or negative charges in liquid helium is essential to comprehend charge-induced processes in molecular systems embedded in helium droplets. Here, we report the resonant formation of excited metastable atomic and molecular helium anions in superfluid helium droplets upon electron impact. Although the molecular anion is heliophobic and migrates toward the surface of the helium droplet, the excited metastable atomic helium anion is bound within the helium droplet and exhibits high mobility. The atomic anion is shown to be responsible for the formation of molecular dopant anions upon charge transfer and thus, we clarify the nature of the previously unidentified fast exotic negative charge carrier found in bulk liquid helium.
Collapse
Affiliation(s)
- Andreas Mauracher
- Institut
für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25/3, A-6020 Innsbruck, Austria
| | - Matthias Daxner
- Institut
für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25/3, A-6020 Innsbruck, Austria
| | - Johannes Postler
- Institut
für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25/3, A-6020 Innsbruck, Austria
| | - Stefan
E. Huber
- Institut
für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25/3, A-6020 Innsbruck, Austria
| | - Stephan Denifl
- Institut
für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25/3, A-6020 Innsbruck, Austria
| | - Paul Scheier
- Institut
für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25/3, A-6020 Innsbruck, Austria
- P. Scheier. E-mail: . Phone: +43 512 507 52260. Fax: +43 512 507
2922
| | - J. Peter Toennies
- Max
Planck Institut für Dynamik und Selbstorganisation, Am Fassberg 17, D-37077 Göttingen, Germany
- J. P. Toennies.
E-mail: . Phone: +49 551 5176
600.
Fax: +49 551 5176 575
| |
Collapse
|
35
|
Huber SE, Mauracher A. On the formation of (anionic) excited helium dimers in helium droplets. J Phys Chem A 2014; 118:6642-7. [PMID: 24866535 PMCID: PMC4141897 DOI: 10.1021/jp503643r] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
![]()
Metastable atomic and molecular helium
anions exhibiting high-spin
quartet configurations can be produced in helium droplets via electron
impact. Their lifetimes allow detection in mass spectrometric experiments.
Formation of atomic helium anions comprises collision-induced excitation
of ground state helium and concomitant electron capture. Yet the formation
of molecular helium anions in helium droplets has been an unresolved
issue. In this work, we explore the interaction of excited helium
atoms exhibiting high-spin triplet configurations with ground state
helium using the equation-of-motion coupled-cluster method. Transition
barriers in the energetically lowest He*–He and He*––He interaction potentials prevent molecule formation at the
extremely low temperatures present in helium droplets. In contrast,
some excited states allow a barrier-free formation of molecular helium
(anions). Moreover, we show that the necessary excitation energies
pinpoint (higher) resonances in recently recorded mass spectra and
emend the assignment of those resonances that have previously been
assigned to electron-impact ionization of ground state helium necessitating
subsequent double-electron capture. Embedding molecules or molecular
clusters in helium droplets is a predestined experimental technique
for the study of phenomena at very low temperatures. Profound knowledge
about active processes in the helium environment is required for a
proper assessment of experimental data.
Collapse
Affiliation(s)
- Stefan E Huber
- Institut für Ionenphysik und Angewandte Physik, Leopold-Franzens-Universität Innsbruck , Technikerstraße 25, A-6020 Innsbruck, Austria
| | | |
Collapse
|
36
|
Postler J, Vizcaino V, Denifl S, Zappa F, Ralser S, Daxner M, Illenberger E, Scheier P. Electron attachment to CO2 embedded in superfluid He droplets. J Phys Chem A 2014; 118:6553-9. [PMID: 24818738 PMCID: PMC4141896 DOI: 10.1021/jp503179d] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
![]()
Electron attachment to CO2 embedded in superfluid He
droplets leads to ionic complexes of the form (CO2)n– and (CO2)nO– and, at much lower intensities,
He containing ions of the form Hem(CO2)nO–. At low
energies (<5 eV), predominantly the non-decomposed complexes (CO2)n– are formed
via two resonance contributions, similar to electron attachment to
pristine CO2 clusters. The significantly different shapes
and relative resonance positions, however, indicate particular quenching
and mediation processes in CO2@He. A series of further
resonances in the energy range up to 67 eV can be assigned to electronic
excitation of He and capture of the inelastically scattered electron
generating (CO2)n– and two additional processes where an intermediately formed He*
leads to the nonstoichiometric anions (CO2)nO–.
Collapse
Affiliation(s)
- Johannes Postler
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck , Technikerstrasse 25, A-6020 Innsbruck, Austria
| | | | | | | | | | | | | | | |
Collapse
|
37
|
Daxner M, Denifl S, Scheier P, Echt O. Doubly charged CO 2 clusters formed by ionization of doped helium nanodroplets. INTERNATIONAL JOURNAL OF MASS SPECTROMETRY 2014; 365-366:200-205. [PMID: 25844051 PMCID: PMC4375666 DOI: 10.1016/j.ijms.2014.01.016] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/15/2013] [Revised: 01/05/2014] [Accepted: 01/22/2014] [Indexed: 06/04/2023]
Abstract
Helium nanodroplets are doped with carbon dioxide and ionized by electrons. Doubly charged cluster ions are, for the first time, identified based on their characteristic patterns of isotopologues. Thanks to the high mass resolution, large dynamic range, and a novel method to eliminate contributions from singly charged ions from the mass spectra, we are able to observe doubly charged cluster ions that are smaller than the ones reported in the past. The likely mechanism by which doubly charged ions are formed in doped helium droplets is discussed.
Collapse
Affiliation(s)
- Matthias Daxner
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstraße 25, A-6020 Innsbruck, Austria
| | - Stephan Denifl
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstraße 25, A-6020 Innsbruck, Austria
| | - Paul Scheier
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstraße 25, A-6020 Innsbruck, Austria
| | - Olof Echt
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstraße 25, A-6020 Innsbruck, Austria
- Department of Physics, University of New Hampshire, Durham, NH 03824, USA
| |
Collapse
|
38
|
|
39
|
Huber SE, Mauracher A. On the properties of charged and neutral, atomic and molecular helium species in helium nanodroplets: interpreting recent experiments. Mol Phys 2013. [DOI: 10.1080/00268976.2013.863403] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
|
40
|
Loginov E, Gomez LF, Vilesov AF. Formation of core-shell silver-ethane clusters in He droplets. J Phys Chem A 2013; 117:11774-82. [PMID: 23767815 DOI: 10.1021/jp402614s] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Here, we have studied the utility of large He droplets of 10(5)-10(7) atoms for the growth of composite clusters consisting of an Ag core and a shell of ethane molecules. The clusters have been assembled by doping He droplets with up to 10(3) Ag atoms and ethane molecules in two sequential pickup cells and studied via infrared spectroscopy in the C-H stretch region of the ethane molecules. We found that the ν7 band of ethane molecules at the interface with the Ag atoms has a low frequency shift of approximately 15 cm(-1) with respect to that of more distant ethane molecules away from the interface. The intensity ratio of the two bands was used for evaluation of the Ag core and ethane shell cluster structure. We found that the number of surface ethane molecules is in good agreement with a model that assumes a dense, core-shell structure for clusters containing less than about 100 atoms. However, large Ag clusters consisting of about 3000 atoms have a factor of about 5 larger surface area than that predicted by the model, indicating a ramified structure for such larger Ag clusters obtained in liquid He. Moreover, we demonstrate that He droplets behave as calorimeters for measurements of the number of captured atoms and molecules as well as the amount of absorbed laser energy.
Collapse
Affiliation(s)
- Evgeny Loginov
- Department of Chemistry, University of Southern California , Los Angeles, California 90089, United States
| | | | | |
Collapse
|
41
|
Volk A, Thaler P, Koch M, Fisslthaler E, Grogger W, Ernst WE. High resolution electron microscopy of Ag-clusters in crystalline and non-crystalline morphologies grown inside superfluid helium nanodroplets. J Chem Phys 2013; 138:214312. [PMID: 23758376 DOI: 10.1063/1.4807843] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Affiliation(s)
- Alexander Volk
- Institute of Experimental Physics, Graz University of Technology, Petersgasse 16, A-8010 Graz, Austria
| | | | | | | | | | | |
Collapse
|
42
|
Pörtner N, Toennies JP, Vilesov AF, Stienkemeier F. Anomalous fine structures of the 000band of tetracene in large He droplets and their dependence on droplet size. Mol Phys 2012. [DOI: 10.1080/00268976.2012.679633] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
|
43
|
An der Lan L, Bartl P, Leidlmair C, Jochum R, Denifl S, Echt O, Scheier P. Solvation of Na+, K+, and their dimers in helium. Chemistry 2012; 18:4411-8. [PMID: 22374575 PMCID: PMC3350777 DOI: 10.1002/chem.201103432] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2011] [Indexed: 11/10/2022]
Abstract
Helium atoms bind strongly to alkali cations which, when embedded in liquid helium, form so-called snowballs. Calculations suggest that helium atoms in the first solvation layer of these snowballs form rigid structures and that their number (n) is well defined, especially for the lighter alkalis. However, experiments have so far failed to accurately determine values of n. We present high-resolution mass spectra of Na+Hen, K+Hen, Na2+Hen and K2+Hen, formed by electron ionization of doped helium droplets; the data allow for a critical comparison with several theoretical studies. For sodium and potassium monomers the spectra indicate that the value of n is slightly smaller than calculated. Na2+Hen displays two distinct anomalies at n=2 and n=6, in agreement with theory; dissociation energies derived from experiment closely track theoretical values. K2+Hen distributions are fairly featureless, which also agrees with predictions.
Collapse
Affiliation(s)
- Lukas An der Lan
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstrasse 25, 6020 Innsbruck, Austria
| | | | | | | | | | | | | |
Collapse
|
44
|
Abstract
Helium droplets spanning a wide size range, N(He) = 10(3)-10(10), were formed in a continuous-nozzle beam expansion at different nozzle temperatures and a constant stagnation pressure of 20 bars. The average sizes of the droplets have been obtained by attenuation of the droplet beam through collisions with argon and helium gases at room temperature. The results obtained are in good agreement with previous measurements in the size range N(He) = 10(5)-10(7). Moreover, the measurements give the average sizes in the previously uncharacterized range of very large droplets of 10(7)-10(10) atoms. The droplet sizes and beam flux increase rapidly at nozzle temperatures below 6 K, which is ascribed to the formation of droplets within the nozzle interior. The mass spectra of the droplet beam upon electron impact ionization have also been obtained. The spectra show a large increase in the intensity of the He(4) (+) signal upon increase of the droplet size, an effect which can be used as a secondary size standard in the droplet size range N(He) = 10(4)-10(9) atoms.
Collapse
Affiliation(s)
- Luis F Gomez
- Department of Chemistry, University of Southern California, Los Angeles, California 90089, USA
| | | | | | | |
Collapse
|
45
|
Filsinger F, Ahn DS, Meijer G, von Helden G. Photoexcitation of mass/charge selected hemin+, caught in helium nanodroplets. Phys Chem Chem Phys 2012; 14:13370-7. [DOI: 10.1039/c2cp42071f] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
|
46
|
An der Lan L, Bartl P, Leidlmair C, Schöbel H, Jochum R, Denifl S, Märk TD, Ellis AM, Scheier P. The submersion of sodium clusters in helium nanodroplets: identification of the surface → interior transition. J Chem Phys 2011; 135:044309. [PMID: 21806121 DOI: 10.1063/1.3610388] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The submersion of sodium clusters beyond a critical size in helium nanodroplets, which has recently been predicted on theoretical grounds, is demonstrated for the first time. Confirmation of a clear transition from a surface location, which occurs for alkali atoms and small clusters, to full immersion for larger clusters, is provided by identifying the threshold electron energy required to initiate Na(n) cluster ionization. On the basis of these measurements, a lower limit for the cluster size required for submersion, n ≥ 21, has been determined. This finding is consistent with the recent theoretical prediction.
Collapse
Affiliation(s)
- Lukas An der Lan
- Institut für Ionenphysik und Angewandte Physik und Research Platform Advanced Materials, Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria
| | | | | | | | | | | | | | | | | |
Collapse
|
47
|
Loginov E, Gomez LF, Chiang N, Halder A, Guggemos N, Kresin VV, Vilesov AF. Photoabsorption of Ag(n)(N∼6-6000) nanoclusters formed in helium droplets: transition from compact to multicenter aggregation. PHYSICAL REVIEW LETTERS 2011; 106:233401. [PMID: 21770503 DOI: 10.1103/physrevlett.106.233401] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2010] [Indexed: 05/12/2023]
Abstract
Ag(N) clusters with up to thousands of atoms were grown in large He droplets and studied by optical spectroscopy. For N≲10(3) the spectra are dominated by a surface plasmon resonance near 3.8 eV and a broad feature in the UV, consistent with absorption by individual metallic particles. Larger clusters reveal unexpectedly strong broad absorption at low frequencies, extending down to ≈0.5 eV. This suggests a transition from single-center to multicenter formation, in agreement with estimates of cluster growth kinetics in He droplets. Moreover, the spectra of large clusters develop a characteristic dispersion profile at 3.5-4.5 eV, indicative of the coexistence of localized and delocalized electronic excitations in composite clusters, as predicted theoretically.
Collapse
Affiliation(s)
- Evgeny Loginov
- Department of Chemistry, University of Southern California, Los Angeles, California 90089, USA
| | | | | | | | | | | | | |
Collapse
|
48
|
Loginov E, Gomez LF, Vilesov AF. Surface Deposition and Imaging of Large Ag Clusters Formed in He Droplets. J Phys Chem A 2011; 115:7199-204. [DOI: 10.1021/jp200198n] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Affiliation(s)
- Evgeny Loginov
- Department of Chemistry, University of Southern California, Los Angeles, California 90089, United States
| | - Luis F. Gomez
- Department of Chemistry, University of Southern California, Los Angeles, California 90089, United States
| | - Andrey F. Vilesov
- Department of Chemistry, University of Southern California, Los Angeles, California 90089, United States
| |
Collapse
|
49
|
von Haeften K, Laarmann T, Wabnitz H, Möller T, Fink K. Size and Isotope Effects of Helium Clusters and Droplets: Identification of Surface and Bulk-Volume Excitations. J Phys Chem A 2011; 115:7316-26. [DOI: 10.1021/jp2008489] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Klaus von Haeften
- Department of Physics and Astronomy, University of Leicester, Leicester LE1 7RH, United Kingdom
| | - Tim Laarmann
- Deutsches Elektronen-Synchrotron DESY, 22603 Hamburg, Germany
| | | | - Thomas Möller
- Institut für Optik und Atomare Physik, Technische Universität Berlin, Hardenbergstrasse 36, 10623 Berlin, Germany
| | - Karin Fink
- Institut für Nanotechnologie, Karlsruher Institut für Technologie, Postfach 3640, 76021 Karlsruhe, Germany
| |
Collapse
|
50
|
Schöbel H, Bartl P, Leidlmair C, Daxner M, Zöttl S, Denifl S, Märk TD, Scheier P, Spångberg D, Mauracher A, Bohme DK. Sequential penning ionization: harvesting energy with ions. PHYSICAL REVIEW LETTERS 2010; 105:243402. [PMID: 21231525 DOI: 10.1103/physrevlett.105.243402] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2010] [Indexed: 05/30/2023]
Abstract
We report the observation of the ejection of electrons caused by collisions of excited atoms with ions, rather than neutrals, leading to the production of doubly charged ions. Doping superfluid He droplets with methyl iodide and exposing them to electrons enhances the formation of doubly charged iodine atoms at the threshold for the production of two metastable He atoms. These observations point toward a novel ionization process where doubly charged ions are produced by sequential Penning ionization. In some cases, depending on the neutral target, the process also leads to a subsequent Coulomb explosion of the dopant.
Collapse
Affiliation(s)
- Harald Schöbel
- Institute for Ion Physics and Applied Physics, University of Innsbruck, 6020 Innsbruck, Austria
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|