1
|
Lackner F, Ernst WE. Photoinduced Molecule Formation of Spatially Separated Atoms on Helium Nanodroplets. J Phys Chem Lett 2018; 9:3561-3566. [PMID: 29893573 DOI: 10.1021/acs.jpclett.8b01530] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Besides the use as cold matrix for spectroscopic studies, superfluid helium droplets have served as a cold environment for the synthesis of molecules and clusters. Since vibrational frequencies of molecules in helium droplets exhibit almost no shift compared to the free molecule values, one could assume the solvated particles move frictionless and undergo a reaction as soon as their paths cross. There have been a few unexplained observations that seemed to indicate cases of two species on one droplet not forming bonds but remaining isolated. In this work, we performed a systematic study of helium droplets doped with one rubidium and one strontium atom showing that besides a reaction to RbSr, there is a probability of finding separated Rb and Sr atoms on one droplet that only react after electronic excitation. Our results further indicate that ground-state Sr atoms can reside at the surface as well as inside the droplet.
Collapse
Affiliation(s)
- Florian Lackner
- Institute of Experimental Physics , Graz University of Technology , Petersgasse 16 , A-8010 Graz , Austria, European Union
| | - Wolfgang E Ernst
- Institute of Experimental Physics , Graz University of Technology , Petersgasse 16 , A-8010 Graz , Austria, European Union
| |
Collapse
|
2
|
Ancilotto F, Barranco M, Coppens F, Eloranta J, Halberstadt N, Hernando A, Mateo D, Pi M. Density functional theory of doped superfluid liquid helium and nanodroplets. INT REV PHYS CHEM 2017. [DOI: 10.1080/0144235x.2017.1351672] [Citation(s) in RCA: 55] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Affiliation(s)
- Francesco Ancilotto
- Dipartimento di Fisica e Astronomia ‘Galileo Galilei’ and CNISM, Università di Padova, Padova, Italy
- CNR-IOM Democritos, Trieste, Italy
| | - Manuel Barranco
- Facultat de Física, Departament FQA, Universitat de Barcelona, Barcelona, Spain
- Institute of Nanoscience and Nanotechnology (IN2UB), Universitat de Barcelona, Barcelona, Spain
- Laboratoire des Collisions, Agrégats et Réactivité, IRSAMC, Université Toulouse 3 and CNRS, Toulouse Cedex 09, France
| | - François Coppens
- Laboratoire des Collisions, Agrégats et Réactivité, IRSAMC, Université Toulouse 3 and CNRS, Toulouse Cedex 09, France
| | - Jussi Eloranta
- Department of Chemistry and Biochemistry, California State University at Northridge, Northridge, CA, USA
| | - Nadine Halberstadt
- Laboratoire des Collisions, Agrégats et Réactivité, IRSAMC, Université Toulouse 3 and CNRS, Toulouse Cedex 09, France
| | - Alberto Hernando
- Social Thermodynamics Applied Research (SThAR), EPFL Innovation Park, Lausanne, Switzerland
| | - David Mateo
- Applied Complexity Group, Singapore University of Technology and Design, Singapore, Singapore
| | - Martí Pi
- Facultat de Física, Departament FQA, Universitat de Barcelona, Barcelona, Spain
- Institute of Nanoscience and Nanotechnology (IN2UB), Universitat de Barcelona, Barcelona, Spain
| |
Collapse
|
3
|
Brice JT, Liang T, Raston PL, McCoy AB, Douberly GE. Infrared Stark and Zeeman spectroscopy of OH–CO: The entrance channel complex along the OH + CO → trans-HOCO reaction pathway. J Chem Phys 2016; 145:124310. [DOI: 10.1063/1.4963226] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Joseph T. Brice
- Department of Chemistry, University of Georgia, Athens, Georgia 30602, USA
| | - Tao Liang
- Department of Chemistry, University of Georgia, Athens, Georgia 30602, USA
| | - Paul L. Raston
- Department of Chemistry and Biochemistry, James Madison University, Harrisonburg, Virginia 22807, USA
| | - Anne B. McCoy
- Department of Chemistry, University of Washington, Seattle, Washington 98195, USA
| | - Gary E. Douberly
- Department of Chemistry, University of Georgia, Athens, Georgia 30602, USA
| |
Collapse
|
4
|
Chen L, Zhang J, Freund WM, Kong W. Effect of kinetic energy on the doping efficiency of cesium cations into superfluid helium droplets. J Chem Phys 2015; 143:044310. [PMID: 26233132 PMCID: PMC4522010 DOI: 10.1063/1.4927471] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2015] [Accepted: 07/15/2015] [Indexed: 11/14/2022] Open
Abstract
We present an experimental investigation of the effect of kinetic energy on the ion doping efficiency of superfluid helium droplets using cesium cations from a thermionic emission source. The kinetic energy of Cs(+) is controlled by the bias voltage of a collection grid collinearly arranged with the droplet beam. Efficient doping from ions with kinetic energies from 20 eV up to 480 V has been observed in different sized helium droplets. The relative ion doping efficiency is determined by both the kinetic energy of the ions and the average size of the droplet beam. At a fixed source temperature, the number of doped droplets increases with increasing grid voltage, while the relative ion doping efficiency decreases. This result implies that not all ions are captured upon encountering with a sufficiently large droplet, a deviation from the near unity doping efficiency for closed shell neutral molecules. We propose that this drop in ion doping efficiency with kinetic energy is related to the limited deceleration rate inside a helium droplet. When the source temperature changes from 14 K to 17 K, the relative ion doping efficiency decreases rapidly, perhaps due to the lack of viable sized droplets. The size distribution of the Cs(+)-doped droplet beam can be measured by deflection and by energy filtering. The observed doped droplet size is about 5 × 10(6) helium atoms when the source temperature is between 14 K and 17 K.
Collapse
Affiliation(s)
- Lei Chen
- Department of Chemistry, Oregon State University, Corvallis, Oregon 97331, USA
| | - Jie Zhang
- Department of Chemistry, Oregon State University, Corvallis, Oregon 97331, USA
| | - William M Freund
- Department of Chemistry, Oregon State University, Corvallis, Oregon 97331, USA
| | - Wei Kong
- Department of Chemistry, Oregon State University, Corvallis, Oregon 97331, USA
| |
Collapse
|
5
|
Hauser AW, Volk A, Thaler P, Ernst WE. Atomic collisions in suprafluid helium-nanodroplets: timescales for metal-cluster formation derived from He-density functional theory. Phys Chem Chem Phys 2015; 17:10805-12. [PMID: 25812719 PMCID: PMC4441260 DOI: 10.1039/c5cp01110h] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2015] [Accepted: 03/17/2015] [Indexed: 11/21/2022]
Abstract
Collision times for the coinage metal atoms Cu, Ag and Au in He-droplets are derived from helium density functional theory and molecular dynamics simulations. The strength of the attractive interaction between the metal atoms turns out to be less important than the mass of the propagating metal atoms. Even for small droplets consisting of a few thousand helium atoms, the collision times are shortest for Cu, followed by Ag and Au, despite the higher binding energy of Au2 compared to Cu2.
Collapse
Affiliation(s)
- Andreas W. Hauser
- 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 . ;
| | - Philipp Thaler
- 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
|
6
|
Douberly GE, Raston PL, Liang T, Marshall MD. Infrared rovibrational spectroscopy of OH–C2H2 in 4He nanodroplets: Parity splitting due to partially quenched electronic angular momentum. J Chem Phys 2015; 142:134306. [DOI: 10.1063/1.4916394] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Gary E. Douberly
- Department of Chemistry, University of Georgia, Athens, Georgia 30602-2556, USA
| | - Paul L. Raston
- Department of Chemistry, University of Adelaide, Adelaide, South Australia 5005, Australia
| | - Tao Liang
- Department of Chemistry, University of Georgia, Athens, Georgia 30602-2556, USA
| | - Mark D. Marshall
- Department of Chemistry, Amherst College, Amherst, Massachusetts 01002-5000, USA
| |
Collapse
|
7
|
Loginov E, Hernando A, Beswick JA, Halberstadt N, Drabbels M. Excitation of Sodium Atoms Attached to Helium Nanodroplets: The 3p ← 3s Transition Revisited. J Phys Chem A 2015; 119:6033-44. [DOI: 10.1021/jp511885t] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
| | | | - J. Alberto Beswick
- Laboratoire
des Collisions, Agrégats, Réactivité, IRSAMC, CNRS and Université Toulouse 3 Paul Sabatier, 31062 Toulouse, France
| | - Nadine Halberstadt
- Laboratoire
des Collisions, Agrégats, Réactivité, IRSAMC, CNRS and Université Toulouse 3 Paul Sabatier, 31062 Toulouse, France
| | | |
Collapse
|
8
|
Kautsch A, Koch M, Ernst WE. Photoinduced molecular dissociation and photoinduced recombination mediated by superfluid helium nanodroplets. Phys Chem Chem Phys 2015; 17:12310-6. [DOI: 10.1039/c5cp01009h] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Photoinduced predissociation of Cr2 in helium nanodroplets causes stable, quantum state specific spatial separation followed by geminate recombination upon photoionization.
Collapse
Affiliation(s)
- Andreas Kautsch
- Graz University of Technology
- Institute of Experimental Physics
- NAWI Graz
- A-8010 Graz
- Austria
| | - Markus Koch
- Graz University of Technology
- Institute of Experimental Physics
- NAWI Graz
- A-8010 Graz
- Austria
| | - Wolfgang E. Ernst
- Graz University of Technology
- Institute of Experimental Physics
- NAWI Graz
- A-8010 Graz
- Austria
| |
Collapse
|
9
|
Hernando A, Beswick JA, Halberstadt N. Communication: Angular momentum alignment and fluorescence polarization of alkali atoms photodetached from helium nanodroplets. J Chem Phys 2013; 139:221102. [DOI: 10.1063/1.4843235] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
|
10
|
Zhang C, Zhang Z, Huang C, Zhang Q, Chen Y. Helium Droplets: An Apparatus to Study Ultra Cold Chemistry. CHINESE J CHEM PHYS 2013. [DOI: 10.1063/1674-0068/26/03/270-276] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
|
11
|
Hauser AW, Gruber T, Filatov M, Ernst WE. Shifts in the ESR spectra of alkali-metal atoms (Li, Na, K, Rb) on helium nanodroplets. Chemphyschem 2013; 14:716-22. [PMID: 23125112 PMCID: PMC3648978 DOI: 10.1002/cphc.201200697] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2012] [Revised: 10/15/2012] [Indexed: 11/06/2022]
Abstract
He-droplet-induced changes of the hyperfine structure constants of alkali-metal atoms are investigated by a combination of relativistically corrected ab initio methods with a simulation of the helium density distribution based on He density functional theory. Starting from an accurate description of the variation of the hyperfine structure constant in the M-He diatomic systems (M=Li, Na, K, Rb) as a function of the interatomic distance we simulate the shifts induced by droplets of up to 10,000 (4)He atoms. All theoretical predictions for the relative shifts in the isotropic hyperfine coupling constants of the alkali-metal atoms attached to helium droplets of different size are then tied to a single, experimentally derived parameter of Rb.
Collapse
Affiliation(s)
- Andreas W Hauser
- Institute of Experimental Physics, Graz University of Technology, Petersgasse 16, 8010 Graz, Austria.
| | | | | | | |
Collapse
|
12
|
Raston PL, Liang T, Douberly GE. Anomalous Λ-Doubling in the Infrared Spectrum of the Hydroxyl Radical in Helium Nanodroplets. J Phys Chem A 2013; 117:8103-10. [DOI: 10.1021/jp312335q] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Paul L. Raston
- Department
of Chemistry, University of Georgia, Athens, Georgia 30602, United States
| | - Tao Liang
- Department
of Chemistry, University of Georgia, Athens, Georgia 30602, United States
| | - Gary E. Douberly
- Department
of Chemistry, University of Georgia, Athens, Georgia 30602, United States
| |
Collapse
|
13
|
Hernando A, Masson A, Briant M, Mestdagh JM, Gaveau MA, Halberstadt N. Fluorescence emission of Ca-atom from photodissociated Ca2 in Ar doped helium droplets. II. Theoretical. J Chem Phys 2012; 137:184311. [PMID: 23163375 DOI: 10.1063/1.4762837] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The stability of the ground or excited state calcium atom in an argon-doped helium droplet has been investigated using an extension of the helium density functional method to treat clusters. This work was motivated by the experimental study presented in a companion paper, hereafter called Paper I [A. Masson, M. Briant, J. M. Mestdagh, M. A. Gaveau, A. Hernando, and N. Halberstadt, J. Chem. Phys. 137, 184310 (2012)], which investigated Ca(2) photodissociation in an argon-doped helium droplet and the nature of the fluorescent species. It is found that one single argon atom is sufficient to bring the calcium atom inside the droplet, for droplets of over 200 helium atoms. The absorption and emission spectra of CaAr(M) (M = 0-7) clusters have been simulated using the recently developed density sampling method to describe the influence of the helium environment. Absorption spectra exhibit broad, double bands that are significantly blueshifted with respect to the calcium atomic line. The emission spectra are less broad and redshifted with respect to the calcium resonance line. The shifts are found to be additive only for M ≤ 2, because only the first two argon atoms are located in equivalent positions around the calcium p orbital. This finding gives a justification for the fit presented in the companion paper, which uses the observed shifts in the emission spectra as a function of argon pressure to deduce the shifts as a function of the number of argon atoms present in the cluster. An analysis of this fit is presented here, based on the calculated shifts. It is concluded that the emitting species following Ca(2) photodissociation in an argon-doped droplet in Paper I could be Ca∗Ar(M) in a partly evaporated droplet where less than 200 helium atoms remain.
Collapse
Affiliation(s)
- A Hernando
- Laboratoire des Collisions, Agrégats, Réactivité, IRSAMC, UMR 5589, CNRS et Université Paul Sabatier-Toulouse 3, 118 route de Narbonne, F-31062 Toulouse Cedex 09, France
| | | | | | | | | | | |
Collapse
|
14
|
Poms J, Hauser AW, Ernst WE. Helium nanodroplets doped with xenon and rubidium atoms: a case study of van der Waals interactions between heliophilic and heliophobic dopants. Phys Chem Chem Phys 2012; 14:15158-65. [DOI: 10.1039/c2cp42333b] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
15
|
Liang T, Flynn SD, Morrison AM, Douberly GE. Quantum Cascade Laser Spectroscopy and Photoinduced Chemistry of Al–(CO)n Clusters in Helium Nanodroplets. J Phys Chem A 2011; 115:7437-47. [DOI: 10.1021/jp203367t] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Tao Liang
- Department of Chemistry, University of Georgia, Athens, Georgia 30602, United States
| | - Steven D. Flynn
- Department of Chemistry, University of Georgia, Athens, Georgia 30602, United States
| | - Alexander M. Morrison
- Department of Chemistry, University of Georgia, Athens, Georgia 30602, United States
| | - Gary E. Douberly
- Department of Chemistry, University of Georgia, Athens, Georgia 30602, United States
| |
Collapse
|