Photon Echo of Pentacene Molecules Introduced in Crystals with High Concentration
Yuzo Yoshikuni, Arao Nakamura, Shigeo Shionoya
Abstract Photon echo decay time is measured for pentacence molecules introduced in naphthalene and p-terphenyl crystals with rather high concentrations (10−6–105 mol/mol) at temperatures between 1.6 K and 4.1 K, using a tunable picosecond laser system consisting of a mode-locked YAG laser and a parametric oscillator. In naphthalene echo decay time increases with lowering temperature approaching a constant value below 2 K, but in p-terphenyl it is almost constant. The phase relaxation time at very low temperature is much shorter than twice the population relaxation time in both crystals, indicating that pure dephasing processes exist. Analyzing the results it turns out that there exsists a pure dephasing process which is temperature-independent and is very probably due to interactions between pentacene molecules, in addition to the temperature-dependent dephasing process due to the scattering of pseudolocalized phonons.
Bulletin of the Chemical Society of Japan•Sep 1, 1982•5 citations