Dissemin is shutting down on January 1st, 2025

Published in

Wiley, ChemPhysChem, 4(6), p. 719-731, 2005

DOI: 10.1002/cphc.200400489

Links

Tools

Export citation

Search in Google Scholar

Ab initio calculations and Franck-Condon simulation of the absorption spectra of GeCl2 including anharmonicity

Journal article published in 2005 by Daniel K. W. Mok ORCID, Foo-Tim Chau, Edmond P. F. Lee, John M. Dyke
This paper is available in a repository.
This paper is available in a repository.

Full text: Download

Green circle
Preprint: archiving allowed
Orange circle
Postprint: archiving restricted
Red circle
Published version: archiving forbidden
Data provided by SHERPA/RoMEO

Abstract

Geometrical parameters, vibrational frequencies and relative electronic energies of the X(-1)A(1), a(-3)B(1) and A(1)B(1) states of GeCl2 have been calculated at the CCSD(T) and/or CASSCF/MRCI level with basis sets of up to aug-cc-pV5Z quality. Core electron correlation and relativistic contributions were also investigated. RCCSD(T)/aug-cc-pVQZ potential energy functions (PEFs) of the X(1)A(1) and a(3)B(1) states, and a CASSCF/MRCI/aug-cc-pVQZ PEF of the A(1)B(1) state of GeCl2 are reported. Anharmonic vibrational wavefunctions of these electronic states of GeCl2, obtained variationally using the computed PEFs, are employed to calculate the Franck-Condon factors (FCFs) of the a-X and A-X transitions of GeCl2. Simulated absorption spectra of these transitions based on the computed FCFs are compared with the corresponding experimental laser-induced fluorescence (LIF) spectra of Karolczak et al. [J. Chem. Phys. 1993, 98, 60-70]. Excellent agreement is obtained between the simulated absorption spectrum and observed LIF spectrum of the a-X transition of GeCl2 which confirms the molecular carrier, the electronic states involved and the vibrational assignments of the LIF spectrum. However, comparison between the simulated absorption spectrum and experimental LIF spectrum of the A-X transition of GeCl2 leads to a revision of vibrational assignments of the of the LIF spectrum and suggests that the X(1)A(1) state of GeCl2 was prepared in the experimental work, with a non-Boltzmann vibrational population distribution. The X(0,0,1) level is populated over 4000 times more than expected from a Boltzmann distribution at 60 K, which is appropriate for the relative population of the other low-lying vibrational levels, such as the X(1,0,0) and X(0,1,0) levels.