scholarly journals Conformer-dependent vacuum ultraviolet photodynamics and chiral asymmetries in pure enantiomers of gas phase proline

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Rim Hadidi ◽  
Dušan K. Božanić, ◽  
Hassan Ganjitabar ◽  
Gustavo A. Garcia ◽  
Ivan Powis ◽  
...  
Keyword(s):  
Gas Phase ◽  
Vacuum Ultraviolet ◽  
Energy Difference ◽  
Molecular Structures ◽  
Fragmentation Behavior ◽  
Conformational Landscape ◽  
Vuv Photoionization ◽  
Molecular Electronic Structure ◽  
Unique Amino Acid ◽  
Structure Calculations

AbstractProline is a unique amino-acid, with a secondary amine fixed within a pyrrolidine ring providing specific structural properties to proline-rich biopolymers. Gas-phase proline possesses four main H-bond stabilized conformers differing by the ring puckering and carboxylic acid orientation. The latter defines two classes of conformation, whose large ionization energy difference allows a unique conformer-class tagging via electron spectroscopy. Photoelectron circular dichroism (PECD) is an intense chiroptical effect sensitive to molecular structures, hence theorized to be highly conformation-dependent. Here, we present experimental evidence of an intense and striking conformer-specific PECD, measured in the vacuum ultraviolet (VUV) photoionization of proline, as well as a conformer-dependent cation fragmentation behavior. This finding, combined with theoretical modeling, allows a refinement of the conformational landscape and energetic ordering, that proves inaccessible to current molecular electronic structure calculations. Additionally, astrochemical implications regarding a possible link of PECD to the origin of life’s homochirality are considered in terms of plausible temperature constraints.

scholarly journals Conformer-Dependent VUV Photodynamics and Chiral Asymmetries in Pure Enantiomers of Gas Phase Proline

2020 ◽  
Author(s):  
Rim Hadidi ◽  
Dusan Bozanic ◽  
Hassan Ganjitabar ◽  
Gustavo Garcia ◽  
Ivan Powis ◽  
...  
Keyword(s):  
Gas Phase ◽  
Energy Difference ◽  
Molecular Structures ◽  
Theoretical Modelling ◽  
Pyrrolidine Ring ◽  
Conformational Landscape ◽  
Vuv Photoionization ◽  
Molecular Electronic Structure ◽  
Unique Amino Acid ◽  
Structure Calculations

Abstract Proline is a unique amino-acid, with a secondary amine fixed within a pyrrolidine ring providing specific structural properties to proline-rich biopolymers. Gas-phase proline possesses four main H-bond stabilized conformers differing by the ring puckering and carboxylic acid orientation. The latter defines two classes of conformation, whose large ionization energy difference allows a unique conformer-class tagging via electron spectroscopy. Photoelectron circular dichroism (PECD) is an intense chiroptical effect sensitive to molecular structures, hence theorized to be highly conformation-dependent. Here, besides a conformer-dependant cation fragmentation behaviour, we present experimental evidence of an intense and striking conformer-specific PECD, measured in the VUV photoionization of proline. This finding, combined with theoretical modelling, allows a refinement of the conformational landscape and energetic ordering, that proves inaccessible to current molecular electronic structure calculations. Additionally, astrochemical implications regarding a possible link of PECD to the origin of life’s homochirality are considered in terms of plausible temperature constraints.

Vacuum ultraviolet photochemistry of sulfuric acid vapor： A combined experimental and theoretical study

2021 ◽  
Author(s):  
Cuihong Zhang ◽  
Xiaoxiao Lin ◽  
Xiaofeng Tang ◽  
Christa Fittschen ◽  
Sebastian Hartweg ◽  
...  
Keyword(s):  
Sulfuric Acid ◽  
Synchrotron Radiation ◽  
Energy Range ◽  
Gas Phase ◽  
Vacuum Ultraviolet ◽  
Theoretical Study ◽  
Acid Vapor ◽  
Vuv Photoionization

We present a vacuum ultraviolet (VUV) photoionization study of the gas-phase sulfuric acid (H2SO4) molecule in the 11-14 eV energy range by using the method of synchrotron radiation-based double imaging...

Gas-phase electron-diffraction studies of the molecular structures of tetrachlorosulfidotungsten(VI), WSCl4, and tetrachloroselenotungsten(VI), WSeCl4

1982 ◽  
Vol 21 (9) ◽  
pp. 3280-3283 ◽  
Author(s):  
Elizabeth M. Page ◽  
David A. Rice ◽  
Kolbjoern. Hagen ◽  
Lise. Hedberg ◽  
Kenneth. Hedberg
Keyword(s):  
Electron Diffraction ◽  
Gas Phase ◽  
Molecular Structures ◽  
Gas Phase Electron Diffraction

Intrinsic Optical Absorption in Germanium

1964 ◽  
Vol 19 (5) ◽  
pp. 548-552
Author(s):  
Günther Harbeke
Keyword(s):  
Optical Absorption ◽  
Low Temperatures ◽  
Energy Difference ◽  
Direct Absorption ◽  
Band Structure Calculations ◽  
Bulk Single Crystals ◽  
Transmission Measurements ◽  
Absorption Constant ◽  
Valence Bands ◽  
Structure Calculations

The absorption constant of germanium beyond the first direct absorption edge has been determined up to energies of 2.5 eV by transmission measurements on very thin samples prepared from bulk single crystals. The results are discussed in terms of recent band structure calculations and previous reflection measurements. At low temperatures the observed structure gives evidence for exciton formation connected with direct transitions at a saddle point in the energy difference between conduction and valence bands.

Molecular Structures and Compositions oftrans-1,2-Dichlorocyclohexane andtrans-1,2-Difluorocyclohexane in the Gas Phase:  An Electron-Diffraction Investigation

2006 ◽  
Vol 110 (5) ◽  
pp. 2053-2059 ◽  
Author(s):  
Alan D. Richardson ◽  
Kenneth Hedberg ◽  
Karissa Utzat ◽  
Robert K. Bohn ◽  
Jian-Xin Duan ◽  
...  
Keyword(s):  
Electron Diffraction ◽  
Gas Phase ◽  
Molecular Structures ◽  
Electron Diffraction Investigation

scholarly journals The Potential of Vacuum Ultraviolet Photoionization Mass Spectrometry in Monitoring Photofragmentation of Organometallics

1993 ◽  
Vol 13 (2) ◽  
pp. 113-119 ◽  
Author(s):  
S. Georgiou ◽  
E. Mastoraki ◽  
E. Raptakis ◽  
Z. Xenidi
Keyword(s):  
Molecular Beam ◽  
Vacuum Ultraviolet ◽  
Impact Ionization ◽  
Microwave Discharge ◽  
Fragmentation Pattern ◽  
Photoionization Mass Spectrometry ◽  
Vuv Photoionization ◽  
Ionic Fragmentation ◽  
Deposition Processes ◽  
Fragmentation Patterns

The paper examines the potential of vacuum ultraviolet (VUV) photoionization mass spectroscopy in probing the fragmentation of organometallics in molecular-beam studies and laser-assisted deposition processes. To this end, the ionic fragmentation pattern of few common organometallics, namely metallocenes and carbonyls, is examined at selected VUV wavelengths, produced by microwave-discharge resonance atomic lamps. Discussion of the recorded spectra in terms of the electronic structure of the compounds indicates lack of dynamical bias in the VUV photoionization/fragmentation of metal complexes. Excitation with VUV light results in simpler ionic fragmentation patterns than what observed with electron-impact ionization, thereby enabling accurate monitoring of the excimer-laser photodissociation of organometallics. Finally, the intensity of the VUV ionic signal appears to be adequate for molecular-beam studies. An illustrative example is provided for the study of the 248nm-induced photodesorption of Mo(CO)6 from cryogenic films.

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