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

Chromium doped, deuterated dimethylammonium aluminium sulfate hexahydrate ( DDMAAS) crystals were investigated. The measurements of the photoluminescen ce spectra of these crystals at temperatures above and below its order-diso rder phase transition (T-c(D) = 155.5 K) are reported. The temperature depe ndencies of the luminescence decay curves in a wide temperature range (from 5 to 190 K) were investigated. Results were compared with the data reporte d for dimethylammonium aluminium sulfate hexahydrate (DMAAS) crystal [1]. T he lifetimes of the excited state at 5 K for DMAAS (the sample without deut erium), DDMAAS(1) and DDMAAS(2) were 30, 98 and 408 mus, respectively. Deut eration 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 depen dence of the luminescence lifetimes on the degree of deuteration is non-lin ear. Based on these results the conclusions have been made on the influence of d euterium on the luminescence lifetime and its position in the crystal. The elongation of the luminescence lifetimes has been observed caused by the su bstitution of H atoms by D atoms, The shifting of the internal vibration en ergy to smaller values was noticed according to increase of deuterium conce ntration. The activation energy (E-a) was found as 2155 cm(-1). (C) 2000 El sevier Science B.V. All rights reserved.