Optical spectroscopy of chromium doped deuterated (CH3)(2)NH2Al(SO4)(2)center dot 6H(2)O crystals

摘要

Chromium doped, deuterated dimethylammonium aluminium sulfate hexahydrate (DDMAAS) crystals were investigated. The measurements of the photoluminescence spectra of these crystals at temperatures above and below its order-disorder phase transition (T-c(D) = 155.5 K) are reported. The temperature dependencies of the luminescence decay curves in a wide temperature range (from 5 to 190 K) were investigated. Results were compared with the data reported for dimethylammonium aluminium sulfate hexahydrate (DMAAS) crystal [1]. The lifetimes of the excited state at 5 K for DMAAS (the sample without deuterium), DDMAAS(1) and DDMAAS(2) were 30, 98 and 408 mus, respectively. Deuteration degree of the crystals were estimated from the FT-IR spectra and it amounted to 62 and 86% in DDMAAS(1) and DDMAAS(2), respectively. The dependence of the luminescence lifetimes on the degree of deuteration is non-linear. Based on these results the conclusions have been made on the influence of deuterium on the luminescence lifetime and its position in the crystal. The elongation of the luminescence lifetimes has been observed caused by the substitution of H atoms by D atoms, The shifting of the internal vibration energy to smaller values was noticed according to increase of deuterium concentration. The activation energy (E-a) was found as 2155 cm(-1). (C) 2000 Elsevier Science B.V. All rights reserved. [References: 10]