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Cheng X, Wei M, Tian G, Luo Y, Hua W. Vibrationally-Resolved X-ray Photoelectron Spectra of Six Polycyclic Aromatic Hydrocarbons from First-Principles Simulations. J Phys Chem A 2022; 126:5582-5593. [PMID: 35959595 DOI: 10.1021/acs.jpca.2c04426] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Vibrationally resolved C 1s X-ray photoelectron spectra (XPS) of a series of six polycyclic aromatic hydrocarbons (PAHs; phenanthrene, coronene, naphthalene, anthracene, tetracene, and pentacene) were computed by combining the full core hole density functional theory and the Franck-Condon simulations with the inclusion of the Duschinsky rotation effect. Simulated spectra of phenanthrene, coronene, and naphthalene agree well with experiments both in core binding energies (BEs) and profiles, which validate the accuracy of our predictions for the rest molecules with no high-resolution experiments. We found that three types of carbons i (inner C), p (peripheral C bonded to three C atoms), and h (peripheral C bonded to an H atom) show decreasing BEs. In linear PAHs (the latter four), h-type carbons further split into h1 or h2 (on inner or edge benzene ring) subtypes with chemical shifts of ca. 0.2-0.4 eV. All major Franck-Condon-active modes are characterized to be in-plane vibrations: low-frequency (<800 cm-1) C-C ring deformation modes play an essential role in determining the peak asymmetries; and for each h-type carbon a high-frequency (ca. 3600 cm-1) C*-H stretching mode is responsible for the high-energy tail. We found that core ionization leads to reduction of all C*-C and C*-H bond lengths and ring deformation with a definite direction. Based on theoretical spectra of four linear PAHs, we found asymptotic relations and anticipated possible spectral features for even larger linear PAHs. Our calculations provide accurate reference spectra for XPS characterizations of PAHs, which are useful in understanding the vibronic coupling effects in this family.
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Affiliation(s)
- Xiao Cheng
- Hefei National Laboratory for Physical Science at the Microscale, University of Science and Technology of China, 230026 Hefei, China.,Department of Theoretical Chemistry and Biology, School of Engineering Sciences in Chemistry, Biotechnology and Health, Royal Institute of Technology, SE-106 91, Stockholm, Sweden
| | - Minrui Wei
- MIIT Key Laboratory of Semiconductor Microstructure and Quantum Sensing, Department of Applied Physics, School of Science, Nanjing University of Science and Technology, 210094 Nanjing, China
| | - Guangjun Tian
- Key Laboratory for Microstructural Material Physics of Hebei Province, School of Science, Yanshan University, Qinhuangdao 066004, China
| | - Yi Luo
- Hefei National Laboratory for Physical Science at the Microscale, University of Science and Technology of China, 230026 Hefei, China
| | - Weijie Hua
- MIIT Key Laboratory of Semiconductor Microstructure and Quantum Sensing, Department of Applied Physics, School of Science, Nanjing University of Science and Technology, 210094 Nanjing, China
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Totani R, Ljubić I, Ciavardini A, Grazioli C, Galdenzi F, de Simone M, Coreno M. Frontier orbital stability of nitroxyl organic radicals probed by means of inner shell resonantly enhanced valence band photoelectron spectroscopy. Phys Chem Chem Phys 2022; 24:1993-2003. [PMID: 35018901 DOI: 10.1039/d1cp05264k] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We have investigated the frontier orbitals of persistent organic radicals known as nitroxyls by resonant photoelectron spectroscopy (ResPES) under inner shell excitation. By means of this site-specific technique, we were able to disentangle the different atomic contributions to the outer valence molecular orbitals and examine several core-hole relaxation pathways involving the singly occupied molecular orbital (SOMO) localized on the nitroxyl group. To interpret the ResPES intensity trends, especially the strong enhancement of the SOMO ionized state at the N K-edge, we computed the Dyson spin orbitals (DSOs) pertaining to the transitions between the core-excited initial states and several of the singly ionized valence final states. We found that the computed vertical valence ionization potentials and norms of the DSOs are reasonably reliable when based on the long-range corrected CAM-B3LYP density functional. Thanks to their unpaired electrons, nitroxyls have recently found application in technological fields implying a spin control, such as spintronics and quantum computing. The present findings on the electronic structure of nitroxyl persistent radicals furnish important hints for their implementation in technological devices and, more in general, for the synthesis of new and stable organic radicals with tailored properties.
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Affiliation(s)
- R Totani
- ISM-CNR, LD2 Unit, Basovizza Area Science Park, 34149 Trieste, Italy.
| | - I Ljubić
- Division of Physical Chemistry, Ruđer Bošković Institute, Bijenička cesta 54, HR-10000 Zagreb, Croatia.
| | - A Ciavardini
- University of Nova Gorica, Vipavska 13, SI-5000 Nova Gorica, Slovenia
| | - C Grazioli
- IOM-CNR, Laboratorio TASC, Basovizza SS-14, km 163.5, 34149 Trieste, Italy
| | - F Galdenzi
- University of Nova Gorica, Vipavska 13, SI-5000 Nova Gorica, Slovenia
| | - M de Simone
- IOM-CNR, Laboratorio TASC, Basovizza SS-14, km 163.5, 34149 Trieste, Italy
| | - M Coreno
- ISM-CNR, LD2 Unit, Basovizza Area Science Park, 34149 Trieste, Italy.
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Wasowicz TJ, Ljubic I, Kivimäki A, RICHTER R. Core-shell excitation of isoxazole at the C, N, and O K-edges – an experimental NEXAFS and theoretical TD-DFT study. Phys Chem Chem Phys 2022; 24:19302-19313. [DOI: 10.1039/d2cp02366k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The near-edge X-ray absorption fine structure (NEXAFS) spectra of the gas-phase isoxazole molecule have been measured by collecting total ion yields at the C, N, and O K-edges. The spectral...
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Toffoli D, Grazioli C, Monti M, Stener M, Totani R, Richter R, Schio L, Fronzoni G, Cossaro A. Revealing the electronic properties of the B-B bond: the bis-catecholato diboron molecule. Phys Chem Chem Phys 2021; 23:23517-23525. [PMID: 34642728 DOI: 10.1039/d1cp03428f] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The electronic properties of a diboron molecule, namely bis(catecholato)diboron (2-(1,3,2-benzodioxaborol-2-yl)-1,3,2-benzodioxaborole) (B2Cat2), have been studied by comparing the results of photoemission (XPS) and near edge X-ray absorption spectroscopy (NEXAFS) experiments with the outcome of DFT calculations. The B 1s, C 1s and O 1s K-edges have been investigated for both the isolated gas phase molecule and the adsorbed one on the Au(111) surface. The main features of the polarized NEXAFS spectra at each of the three edges considered are not significantly affected by the presence of the substrate, with respect to the isolated molecule, indicating that the molecule-gold interaction is weak. Moreover, the comparison between the observed dichroism in the NEXAFS spectra of the adsorbed B2Cat2 and that in the NEXAFS spectra of the isolated molecule has confirmed the orbital symmetry assigned in the gas phase absorption spectra. The transitions to π(B-B) bonding and π*(B-B) anti-bonding final states represent the most relevant probe of the chemistry of the B2Cat2 molecule. We show that their theoretical description requires that the treatment of the relaxation changes among different excited state configurations, which we successfully implemented by using ΔSCF-DFT (ΔSCF) calculations.
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Affiliation(s)
- D Toffoli
- Department of Chemical and Pharmaceutical Sciences, University of Trieste, 34127 Trieste, Italy.
| | - C Grazioli
- IOM-CNR, Istituto Officina dei Materiali-CNR, S.S.14, Km 163.5, 34149 Trieste, Italy
| | - M Monti
- Department of Chemical and Pharmaceutical Sciences, University of Trieste, 34127 Trieste, Italy.
| | - M Stener
- Department of Chemical and Pharmaceutical Sciences, University of Trieste, 34127 Trieste, Italy.
| | - R Totani
- ISM-CNR, Istituto di Struttura della Materia, LD2 Unit, 34149 Trieste, Italy
| | - R Richter
- Elettra-Sincrotrone Trieste, 34149 Basovizza, Trieste, Italy
| | - L Schio
- IOM-CNR, Istituto Officina dei Materiali-CNR, S.S.14, Km 163.5, 34149 Trieste, Italy
| | - G Fronzoni
- Department of Chemical and Pharmaceutical Sciences, University of Trieste, 34127 Trieste, Italy.
| | - A Cossaro
- Department of Chemical and Pharmaceutical Sciences, University of Trieste, 34127 Trieste, Italy. .,IOM-CNR, Istituto Officina dei Materiali-CNR, S.S.14, Km 163.5, 34149 Trieste, Italy
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