The effect of asymmetric charge transfer on the IR spectra of excited quadrupolar molecules

The influence of charge transfer symmetry breaking in excited quadrupole molecules of the form D-$\pi$-A-$\pi$-D or A-$\pi$-D-$\pi$-A, where A and D are the electron-acceptor and electron-donor groups, on non-stationary spectra of characteristic vibrations is studied. In the framework of the previously developed theory of symmetry breaking and its manifestations in non-stationary IR spectra, the types of possible changes in IR spectra with an increase in the degree of asymmetry of molecules are classified. A physical interpretation of the revealed regularities is presented and their comparison with the currently available experimental data is carried out.