PRESSURE AND TEMPERATURE DEPENDENCES OF OPTICAL DEPHASING OF THE S-1[-S-0 TRANSITION OF CHLORIN IN POLYCRYSTALLINE N-OCTANE PROBED BY SPECTRAL HOLE-BURNING

The dependences of the width of persistent spectral holes on hydrostatic pressure (P=0-5.5 kbar at T=4.2 K) and on temperature (T=3-12 K at P=1 bar) have been studied for a Shpol'skii system of chlorin molecules in frozen n-octane (C-8:Chl). Both temperature and pressure dependences of the hole width in a 0-0 line at v(00)=15730 cm(-1) can be described within the scope cf a model which takes into account the interaction of the impurity 0-0 transition with a low-frequency quasilocal vibrational mode in the ground electronic state (Omega approximate to l2cm(-1)) and the pressure-induced increase of the frequency of that mode (d Omega/dP=1.5 cm(-1)/kbar). A mode of close parameters in the excited electronic state (Omega'approximate to 15 cm(-1), d Omega'/dP=1.2 cm(-1)/kbar) was found in a site-selected fluorescence excitation spectrum.