ИСТИНА

The absorption bandshapes of Dibenzoylmethanatoboron Difluoride (DBMBF2) with substituents in ortho-, meta-, para-positions of the phenyl ring are theoretically studied. The vibronic absorption structure is calculated using displaced multi-mode harmonic oscillator approximation. The nature of individual peaks in the absorption spectra is clarified. It is shown that the long-wave part of the absorption spectra of ortho- and meta-isomers consist of two overlapping bands while the same part of the absorption spectrum of para-isomer originates from one bright band.It is shown complicated nature of absorption spectrum vibronic bandshape for ortho- and meta-isomers. Relative positions of the vibronic peaks and band width agree well with the experiment. The necessary data: ground-state geometry, frequencies, normal modes, transition energies, oscillator strengths, excited-state geometry displacement are calculated using Density Functional Theory (DFT), Time-Dependent Density Functional Theory (TDDFT) methods with hybrid functional CAM-B3LYP in 6-311G(d,p) basis. The dependence of the band shapes of DBMBF2 derivatives on the position and type of substituent is studied.