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Bogomolov AS, Rogoveshko VM, Baklanov AV. The first shell structure of He environment in tetracene-(He)N clusters manifested in REMPI spectra. Chem Phys Lett 2022. [DOI: 10.1016/j.cplett.2021.139286] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Lottner EM, Slenczka A. Anthracene-Argon Clusters Generated in Superfluid Helium Nanodroplets: New Aspects on Cluster Formation and Microsolvation. J Phys Chem A 2020; 124:311-321. [PMID: 31257886 DOI: 10.1021/acs.jpca.9b04138] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
About two decades after extensive studies on anthracene-Arn clusters in the gas phase, we report corresponding studies in superfluid helium droplets. With AN as a small fluorophore and spectroscopic data from the gas phase and helium droplets, both the formation of clusters and the microsolvation in superfluid helium droplets can be studied. As expected for helium droplets, a significantly higher number of isomeric variants of the respective cluster sizes are obtained, because metastable variants are stabilized by the low temperature and the surrounding helium. Moreover, spectroscopic data recorded in helium droplets reveal cluster configurations with Ar atoms shielded by a helium solvation layer. Surprisingly, AN-Arn clusters with more than four Ar atoms do not appear to form rigid configurations. The helium droplet data in combination with the gas phase spectra may serve as a suitable reference for further theoretical investigations on solvation and cluster formation in superfluid helium droplets.
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Affiliation(s)
- E-M Lottner
- Institut für Physikalische und Theoretische Chemie , Universität Regensburg , 93053 Regensburg , Germany
| | - A Slenczka
- Institut für Physikalische und Theoretische Chemie , Universität Regensburg , 93053 Regensburg , Germany
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Fischer J, Fuchs S, Slenczka A, Karra M, Friedrich B. Microsolvation of porphine molecules in superfluid helium nanodroplets as revealed by optical line shape at the electronic origin. J Chem Phys 2018; 149:244306. [PMID: 30599728 DOI: 10.1063/1.5052615] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We investigate the line shape at the electronic origin of single porphine molecules doped into superfluid helium droplets as a function of the droplet size. Helium droplets comprised of less than 105 atoms are generated from an expansion of gaseous helium, while droplets with more than 105 atoms originate from liquid helium. In contrast to our recent study on phthalocyanine, porphine is found to exhibit a solvent shift to the blue with respect to the gas-phase resonance frequency as well as a multiplet splitting. A comparison of the helium-induced features of phthalocyanine and porphine with those obtained in similar studies on tetracene and pentacene reveals that these occur chiefly as two kinds of excitations distinguished by their linewidths and their dependence on the droplet size. Moreover, at quasi-bulk conditions achieved with droplets in excess of 106 helium atoms, none of these four dopant species yields an optical spectrum that can be assigned to a plausible rotational band structure.
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Affiliation(s)
- J Fischer
- Institut für Physikalische und Theoretische Chemie, Universität Regensburg, 93053 Regensburg, Germany
| | - S Fuchs
- Institut für Physikalische und Theoretische Chemie, Universität Regensburg, 93053 Regensburg, Germany
| | - A Slenczka
- Institut für Physikalische und Theoretische Chemie, Universität Regensburg, 93053 Regensburg, Germany
| | - M Karra
- Fritz-Haber-Insitut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany
| | - B Friedrich
- Fritz-Haber-Insitut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany
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Fuchs S, Fischer J, Slenczka A, Karra M, Friedrich B. Microsolvation of phthalocyanine molecules in superfluid helium nanodroplets as revealed by the optical line shape at electronic origin. J Chem Phys 2018; 148:144301. [PMID: 29655329 DOI: 10.1063/1.5022006] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
We investigate the solvent shift of phthalocyanine (Pc) doped into superfluid helium droplets and probed by optical spectroscopy at the electronic origin. Our present work complements extant studies and provides results that in part contradict previous conclusions. In particular, the solvent shift does not increase monotonously with droplet radius all the way up to the bulk limit, but exhibits just the reverse dependence instead. Moreover, a substructure is resolved, whose characteristics depend on the droplet size. This behavior can hardly be reconciled with that of a freely rotating Pc-helium complex.
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Affiliation(s)
- S Fuchs
- Institut für Physikalische und Theoretische Chemie, Universität Regensburg, 93053 Regensburg, Germany
| | - J Fischer
- Institut für Physikalische und Theoretische Chemie, Universität Regensburg, 93053 Regensburg, Germany
| | - A Slenczka
- Institut für Physikalische und Theoretische Chemie, Universität Regensburg, 93053 Regensburg, Germany
| | - M Karra
- Fritz-Haber-Insitut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany
| | - B Friedrich
- Fritz-Haber-Insitut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany
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Electronic Spectroscopy of Phthalocyanine and Porphyrin Derivatives in Superfluid Helium Nanodroplets. Molecules 2017; 22:molecules22081244. [PMID: 28757568 PMCID: PMC6152379 DOI: 10.3390/molecules22081244] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2017] [Accepted: 07/19/2017] [Indexed: 11/25/2022] Open
Abstract
Phthalocyanine and porphyrin were among the first organic compounds investigated by means of electronic spectroscopy in superfluid helium nanodroplets. Superfluid helium nanodroplets serve as a very gentle host system for preparing cold and isolated molecules. The uniqueness of helium nanodroplets is with respect to the superfluid phase which warrants the vanishing viscosity and, thus, minimal perturbation of the dopant species at a temperature as low as 0.37 K. These are ideal conditions for the study of molecular spectra in order to analyze structures as well as dynamic processes. Besides the investigation of the dopant species itself, molecular spectroscopy in helium droplets provides information on the helium droplet and in particular on microsolvation. This article, as part of a special issue on phthalocyanines and porphyrins, reviews electronic spectroscopy of phthalocyanine and porphyrin compounds in superfluid helium nanodroplets. In addition to the wide variety of medical as well as technical and synthetical aspects, this article discusses electronic spectroscopy of phthalocyanines and porphyrins in helium droplets in order to learn about both the dopant and the helium environment.
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Pentlehner D, Slenczka A. Helium induced fine structure in the electronic spectra of anthracene derivatives doped into superfluid helium nanodroplets. J Chem Phys 2015; 142:014311. [PMID: 25573565 DOI: 10.1063/1.4904899] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Electronic spectra of organic molecules doped into superfluid helium nanodroplets show characteristic features induced by the helium environment. Besides a solvent induced shift of the electronic transition frequency, in many cases, a spectral fine structure can be resolved for electronic and vibronic transitions which goes beyond the expected feature of a zero phonon line accompanied by a phonon wing as known from matrix isolation spectroscopy. The spectral shape of the zero phonon line and the helium induced phonon wing depends strongly on the dopant species. Phonon wings, for example, are reported ranging from single or multiple sharp transitions to broad (Δν > 100 cm(-1)) diffuse signals. Despite the large number of example spectra in the literature, a quantitative understanding of the helium induced fine structure of the zero phonon line and the phonon wing is missing. Our approach is a systematic investigation of related molecular compounds, which may help to shed light on this key feature of microsolvation in superfluid helium droplets. This paper is part of a comparative study of the helium induced fine structure observed in electronic spectra of anthracene derivatives with particular emphasis on a spectrally sharp multiplet splitting at the electronic origin. In addition to previously discussed species, 9-cyanoanthracene and 9-chloroanthracene will be presented in this study for the first time.
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Affiliation(s)
- D Pentlehner
- Institut für Physikalische und Theoretische Chemie, Universität Regensburg, 93040 Regensburg, Germany
| | - A Slenczka
- Institut für Physikalische und Theoretische Chemie, Universität Regensburg, 93040 Regensburg, Germany
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Zhang X, Drabbels M. Elementary Excitations of Superfluid Helium Droplets Probed by Ion Spectroscopy. J Phys Chem Lett 2014; 5:3100-3105. [PMID: 26276319 DOI: 10.1021/jz501530e] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Electronic spectra of molecules in helium droplets reveal spectral features that are related to the elementary excitations of the superfluid helium environment. In order to determine to what extent the interaction strength of the molecule with the helium affects these excitations, the spectrum corresponding to the B̃(2)A″ ← X̃ (2)A″ transition of 2,5-difluorophenol cations in helium droplets has been recorded. The vibronic resonances reveal a sharp zero-phonon line whose width is largely determined by the rotational band contour, followed by a broad structureless phonon wing at higher frequencies. The splitting between the zero-phonon line and phonon wing is approximately half of that found for neutral 2,5-difluorophenol. This difference is attributed to the increased helium density around the ion due to its strong interaction with the helium.
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Affiliation(s)
- Xiaohang Zhang
- Laboratoire de Chimie Physique Moléculaire, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Marcel Drabbels
- Laboratoire de Chimie Physique Moléculaire, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
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Premke T, Wirths EM, Pentlehner D, Riechers R, Lehnig R, Vdovin A, Slenczka A. Microsolvation of molecules in superfluid helium nanodroplets revealed by means of electronic spectroscopy. Front Chem 2014; 2:51. [PMID: 25077143 PMCID: PMC4100322 DOI: 10.3389/fchem.2014.00051] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2014] [Accepted: 06/25/2014] [Indexed: 11/13/2022] Open
Abstract
The empirical model explaining microsolvation of molecules in superfluid helium droplets proposes a non-superfluid helium solvation layer enclosing the dopant molecule. This model warrants an empirical explanation of any helium induced substructure resolved for electronic transitions of molecules in helium droplets. Despite a wealth of such experimental data, quantitative modeling of spectra is still in its infancy. The theoretical treatment of such many-particle systems dissolved into a quantum fluid is a challenge. Moreover, the success of theoretical activities relies also on the accuracy and self-critical communication of experimental data. This will be elucidated by a critical resume of our own experimental work done within the last ten years. We come to the conclusion that spectroscopic data and among others in particular the spectral resolution depend strongly on experimental conditions. Moreover, despite the fact that none of the helium induced fine structure speaks against the empirical model for solvation in helium droplets, in many cases an unequivocal assignment of the spectroscopic details is not possible. This ambiguity needs to be considered and a careful and critical communication of experimental results is essential in order to promote success in quantitatively understanding microsolvation in superfluid helium nanodroplets.
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Affiliation(s)
- Tobias Premke
- Faculty for Chemistry and Pharmacy, Institute for Physical and Theoretical Chemistry, University of Regensburg Regensburg, Germany
| | - Eva-Maria Wirths
- Faculty for Chemistry and Pharmacy, Institute for Physical and Theoretical Chemistry, University of Regensburg Regensburg, Germany
| | | | | | | | | | - Alkwin Slenczka
- Faculty for Chemistry and Pharmacy, Institute for Physical and Theoretical Chemistry, University of Regensburg Regensburg, Germany
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Riechers R, Pentlehner D, Slenczka A. Microsolvation in superfluid helium droplets studied by the electronic spectra of six porphyrin derivatives and one chlorine compound. J Chem Phys 2014; 138:244303. [PMID: 23822240 DOI: 10.1063/1.4811199] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
After almost two decades of high resolution molecular spectroscopy in superfluid helium droplets, the understanding of microsolvation is still the subject of intense experimental and theoretical research. According to the published spectroscopic work including microwave, infrared, and electronic spectroscopy, the latter appears to be particularly promising to study microsolvation because of the appearance of pure molecular transitions and spectrally separated phonon wings. Instead of studying the very details of the influence of the helium environment for one particular dopant molecule as previously done for phthalocyanine, the present study compares electronic spectra of a series of non-polar porphyrin derivatives when doped into helium droplets consisting of 10(4)-10(5) helium atoms. Thereby, we focus on the helium-induced fine structure, as revealed most clearly at the corresponding electronic origin. The interpretation and the assignment of particular features obtained in the fluorescence excitation spectra are based on additional investigations of dispersed emission spectra and of the saturation behavior. Besides many dopant-specific results, the experimental study provides strong evidence for a particular triple peak feature representing the characteristic signature of helium solvation for all seven related dopant species.
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Affiliation(s)
- R Riechers
- Institut für Physikalische und Theoretische Chemie, Universität Regensburg, 93040 Regensburg, Germany
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Affiliation(s)
- J. Peter Toennies
- a Max-Planck-Institut für Dynamik und Selbstorganisation , Göttingen , Germany
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Mateo D, Hernando A, Barranco M, Loginov E, Drabbels M, Pi M. Translational dynamics of photoexcited atoms in 4He nanodroplets: the case of silver. Phys Chem Chem Phys 2013; 15:18388-400. [DOI: 10.1039/c3cp52221k] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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