The Interaction of Impurity Centres with the Surroundings and Quasi‐Line Spectra

The temperature dependence of the integral intensities and the positions and half‐width of the lines in the quasi‐line spectra of 3,4‐benzopyrene, naphthantrone, and dibenzoperopyrene in n‐paraffin matrices are measured and the temperature dependence of the quantum yield of the luminescence is investigated as well. It is shown that with increasing temperature the lines were broadened and shifted and that the integral intensity of the lines decreases slowly. However, it is established that the fall of the integral intensity is not due to a decrease of the probability of the zero‐phonon transition, but is due to a decrease of the quantum yield of the luminescence. — It is shown that the absence of any noticeable change of probability of the zero‐phonon transition in the temperature range 77 to 200 °K is a result of the weak coupling of the impurity with the crystal. The experimental data are interpreted from the point of view of the theory of the spectra of impurity centres in crystals.