Interpretation of the photoelectron, ultraviolet, and vacuum ultraviolet photoabsorption spectra of bromobenzene by ab initio configuration interaction and DFT computations

Journal Article · Wed Oct 28 00:00:00 EDT 2015 · Journal of Chemical Physics

DOI:https://doi.org/10.1063/1.4933419· OSTI ID:22493152

Ridley, Trevor ^[1]; Coreno, Marcello ^[2]; Grazioli, Cesare ^[3]; Zhang, Teng ^[4]; others, and

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1. School of Chemistry, University of Edinburgh, Joseph Black Building, David Brewster Road, Edinburgh EH9 3FJ, Scotland (United Kingdom)
2. CNR-IMIP, Montelibretti, c/o Laboratorio Elettra, Trieste (Italy)
3. CNR-IOM Laboratorio TASC, Trieste (Italy)
4. Department of Physics and Astronomy, University of Uppsala, Uppsala (Sweden)

New photoelectron, ultraviolet (UV), and vacuum UV (VUV) spectra have been obtained for bromobenzene by synchrotron study with higher sensitivity and resolution than previous work. This, together with use of ab initio calculations with both configuration interaction and time dependent density functional theoretical methods, has led to major advances in interpretation. The VUV spectrum has led to identification of a considerable number of Rydberg states for the first time. The Franck-Condon (FC) analyses including both hot and cold bands lead to identification of the vibrational structure of both ionic and electronically excited states including two Rydberg states. The UV onset has been interpreted in some detail, and an interpretation based on the superposition of FC and Herzberg-Teller contributions has been performed. In a similar way, the 6 eV absorption band which is poorly resolved is analysed in terms of the presence of two ππ* states of {sup 1}A{sub 1} (higher oscillator strength) and {sup 1}B{sub 2} (lower oscillator strength) symmetries, respectively. The detailed analysis of the vibrational structure of the 2{sup 2}B{sub 1} ionic state is particularly challenging, and the best interpretation is based on equation-of-motion-coupled cluster with singles and doubles computations. A number of equilibrium structures of the ionic and singlet excited states show that the molecular structure is less subject to variation than corresponding studies for iodobenzene. The equilibrium structures of the 3b{sub 1}3s and 6b{sub 2}3s (valence shell numbering) Rydberg states have been obtained and compared with the corresponding ionic limit structures.

• OSTI ID: 22493152
• Journal Information: Journal of Chemical Physics, Vol. 143, Issue 16; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
97 MATHEMATICAL METHODS AND COMPUTING
ABSORPTION
COMPARATIVE EVALUATIONS
CONFIGURATION INTERACTION
DENSITY FUNCTIONAL METHOD
EQUATIONS OF MOTION
EV RANGE
FAR ULTRAVIOLET RADIATION
MOLECULAR STRUCTURE
OSCILLATOR STRENGTHS
RYDBERG STATES
SENSITIVITY
SPECTRA
SYNCHROTRONS
TIME DEPENDENCE