Multiphonon Processes in the Two-Photon Absorption of T1C1 and the Temperature Dependence of the Band Edge

Abstract

Low-temperature two-photon measurements on T1C1 are reported. For the first time multiphonon sidebands could be resolved in two-photon absorption. A theoretical explanation of line shape is given based on the assumption of resonant intermediate states. In addition, the puzzling temperature dependence of the band edge in T1C1 is cleared up, $\frac{d{E}_{g}}{\mathrm{dT}}$ being positive between 20 and 300 K.