ORCID Profile
0000-0001-9658-2436
Current Organisation
CNRS
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Publisher: Springer Science and Business Media LLC
Date: 26-06-2023
Publisher: American Chemical Society (ACS)
Date: 15-09-2023
Publisher: American Chemical Society (ACS)
Date: 15-10-2015
Abstract: The room-temperature photoabsorption spectra of a number of linear alkynes with internal triple bonds (e.g., 2-butyne, 2-pentyne, and 2- and 3-hexyne) show similar resonances just above the lowest ionization threshold of the neutral molecules. These features result in a substantial enhancement of the photoabsorption cross sections relative to the cross sections of alkynes with terminal triple bonds (e.g., propyne, 1-butyne, 1-pentyne, ...). Based on earlier work on 2-butyne [ Xu et al., J. Chem. Phys. 2012, 136, 154303 ], these features are assigned to excitation from the neutral highest occupied molecular orbital (HOMO) to a shape resonance with g (l = 4) character and approximate π symmetry. This generic behavior results from the similarity of the HOMOs in all internal alkynes, as well as the similarity of the corresponding gπ virtual orbital in the continuum. Theoretical calculations of the absorption spectrum above the ionization threshold for the 2- and 3-alkynes show the presence of a shape resonance when the coupling between the two degenerate or nearly degenerate π channels is included, with a dominant contribution from l = 4. These calculations thus confirm the qualitative arguments for the importance of the l = 4 continuum near threshold for internal alkynes, which should also apply to other linear internal alkynes and alkynyl radicals. The 1-alkynes do not have such high partial waves present in the shape resonance. The lower l partial waves in these systems are consistent with the broader features observed in the corresponding spectra.
Publisher: AIP Publishing
Date: 27-08-2013
DOI: 10.1063/1.4818982
Abstract: The photoionization and pulsed-field-ionization zero-kinetic-energy photoelectron spectra of the propargyl radical have been recorded in the vicinity of the origin of the \\documentclass[12pt]{minimal}\\begin{document}$\\tilde{\\mathrm{X}}^+\\ ^1\\mathrm{A}_1 \\leftarrow \\tilde{\\mathrm{X}}\\ ^2\\mathrm{B}_1$\\end{document}X̃+A11←X̃B12 photoionizing transition. An internally cold s le of propargyl with a rotational temperature of ∼45 K was produced in a supersonic expansion of 1,3-butadiene in helium. Propargyl was generated by excimer laser (ArF, 193 nm) photolysis of 1,3-butadiene in a quartz capillary mounted at the exit of a pulsed valve. The rotational structure of the origin band of the photoelectron spectrum was partially resolved and an improved value of the adiabatic ionization energy of propargyl (EI/hc = 70174.5(20) cm−1) was determined.
Publisher: AIP Publishing
Date: 08-12-2017
DOI: 10.1063/1.5004538
Abstract: The single-photon, photoelectron-photoion coincidence spectrum of N2 has been recorded at high (∼1.5 cm−1) resolution in the region between the N2+ X Σg2+, v+ = 0 and 1 ionization thresholds by using a double-imaging spectrometer and intense vacuum-ultraviolet light from the Synchrotron SOLEIL. This approach provides the relative photoionization cross section, the photoelectron energy distribution, and the photoelectron angular distribution as a function of photon energy. The region of interest contains autoionizing valence states, vibrationally autoionizing Rydberg states converging to vibrationally excited levels of the N2+ X Σg2+ ground state, and electronically autoionizing states converging to the N2+A2Π and B 2Σu+ states. The wavelength resolution is sufficient to resolve rotational structure in the autoionizing states, but the electron energy resolution is insufficient to resolve rotational structure in the photoion spectrum. A simplified approach based on multichannel quantum defect theory is used to predict the photoelectron angular distribution parameters, β, and the results are in reasonably good agreement with experiment.
Publisher: Royal Society of Chemistry (RSC)
Date: 2023
DOI: 10.1039/D3CP04244H
Publisher: AIP Publishing
Date: 16-07-2015
DOI: 10.1063/1.4926541
Abstract: The absolute photoabsorption cross sections of 1- and 2-butyne have been recorded at high resolution by using the vacuum-ultraviolet Fourier-Transform spectrometer at the SOLEIL Synchrotron. Both spectra show more resolved structure than previously observed, especially in the case of 2-butyne. In this work, we assess the potential importance of Rydberg states with higher values of orbital angular momentum, l, than are typically observed in photoabsorption experiments from ground state molecules. We show how the character of the highest occupied molecular orbitals in 1- and 2-butyne suggests the potential importance of transitions to such high-l (l = 3 and 4) Rydberg states. Furthermore, we use theoretical calculations of the partial wave composition of the absorption cross section just above the ionization threshold and the principle of continuity of oscillator strength through an ionization threshold to support this conclusion. The new absolute photoabsorption cross sections are discussed in light of these arguments, and the results are consistent with the expectations. This type of argument should be valuable for assessing the potential importance of different Rydberg series when sufficiently accurate direct quantum chemical calculations are difficult, for ex le, in the n ≥ 5 manifolds of excited states of larger molecules.
Publisher: Informa UK Limited
Date: 11-05-2015
Publisher: American Chemical Society (ACS)
Date: 29-01-2019
Abstract: We present new high-resolution data on the photoionization of the 2-butyn-1-yl radical (CH
No related grants have been discovered for Bérenger Gans.