Photon-echo relaxation measurements with two dye-lasers application to pentacene- h14 and - d14 in p-terphenyl- h crystals at 1.5 K

Abstract

Electronically controlled photon-echo relaxation measurements, using two nitrogen pumped dye-lasers, are reported for mixed crystals of pentacene- h 14 and - d 14 in p-terphenyl- h 14 at 1.5 K. In dilute mixed crystals (ca. 10 −8 M) the photon-echo lifetime is found to be exclusively determined by the fluorescence lifetime. Homogeneous linewidths of 7.1 and 5.9 MHz at 1.5 K are then calculated for the electronic origin of the 1B 2u ← 1A 1g transition of pentacene- h 14 and - d 14 respectively. The decrease in photon-echo lifetime at higher guest concentrations (ca. 10 −7 M) is ascribed to energy transfer between excited and neutral guest molecules.