The potential function of bromoform has been determined in a joint effort, comprising ab initio and genetic algorithm calculations and a refinement to observed and anharmonicity corrected wavenumbers. To this end, the infrared and Raman spectra of HCBr3, DCBr3, and H13CBr3 have been recorded in the gas and liquid phases, those of the last species for the first time. In the analysis of the spectra, a number of combination and overtone bands have been assigned, besides the fundamental vibrations, leading to the determination of some anharmonicity constants. This is also the first experimental determination of such constants for the deuterated and 13C molecules. A Fermi interaction in the spectrum of DCBr3 affecting v4 and v3 + v5 has been interpreted, and the corresponding cubic potential constant has been evaluated. The value of some of the force constants determined in the ab initio and genetic algorithm calculations has been of key importance to allow convergence in the refinement process. The experimental frequencies are well reproduced by the force fields.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry