HYDROSTATIC-PRESSURE EFFECTS ON SPECTRAL HOLE BURNING IN A SHPOLSKII SYSTEM

Hydrostatic-pressure effects on persistent spectral holes in a polycrystalline solid solution of chlorin (Chl) in n-octane (C-8:Chl, a Shpol'skii system) at 4.2 K were studied at high-pressure [up to 8.4 kbars (1 kbar = 750.06 kTorr)] isobaric (burning and recording at the same pressure) conditions as well as in low-pressure (21-39 bars) nonisobaric (burning and recording at different pressures) experiments. A significant decrease of the hole width was seen at high pressures, with the FWHM of holes in the 15 730-cm-1 line being 130 and 45 MHz at 1 bar and 5.5 kbars, respectively. The latter value approaches the normal-pressure lifetime limit of 40 MHz. A pressure-induced site-dependent instability of spectral holes was found at pressures above 5.5 kbars. High-pressure shifts of Shpol'skii lines and low-pressure hole shifts gave the same pressure coefficient, -4.8 cm-1/kbar, for the S1 <-- S0 (0-0) transition energy. This coefficient yielded the value of 13.2 Mbars-1 for the local compressibility. Reversible non-Gaussian non-area-conserving hole broadening was observed in nonisobaric low-pressure experiments.