Photon-echo decay of naphthalene in durene and perdeutero-naphthalene

Abstract

Using two frequency-doubled, nitrogen laser pumped, dye-lasers we have measured the decay of the photon-echo in the lowest 1B1u ← 1A1g singlet state of naphthalene in durene and in perdeutero-naphthalene. Optical phase relaxation in the durene mixed crystal is believed to be caused by resonant phonon scattering in the ground and excited state, and in the isotopically mixed crystal by scattering of the excited state into the singlet exciton band. At the lowest achievable temperature (1.4 K), the photon-echo decay time (T2) in both systems is still found to be much shorter than expected from the fluorescence decay times. Energy transfer is held responsible for this discrepancy.