DEPHASING TIMES OF THE STRETCHING VIBRATION IN LIQUID N-Z AND OF THE VIBRONS IN THE ALPHA-CRYSTALLINE PHASES AND BETA-CRYSTALLINE PHASES

被引:8
作者
DEKINDER, J
GOOVAERTS, E
BOUWEN, A
SCHOEMAKER, D
机构
[1] Physics Department, University of Antwerp (UIA), Antwerp
关键词
D O I
10.1016/0022-2313(90)90211-S
中图分类号
O43 [光学];
学科分类号
070207 ; 0803 ;
摘要
Picosecond time-resolved CARS measurements have been performed on the stretching vibration in liquid N2, and on the vibrons in single crystals of N2 in the α and β phases. Exponential decay was observed in the liquid and β phases. In the α phase the coherence decay could be described by an exponential and a Gaussian factor in the decay signal, corresponding to a homogeneous and an inhomogeneous contribution to the spectral width, respectively. The dephasing times (T2/2) were found to range from 88 ps for the liquid phase to 1.2 ns for α-N2 at 5.6 K. In contrast with theoretical predictions, the Tg vibron decays at the same rate as the Ag vibron, as seen from the beating pattern between the two modes. The factor group splitting between the two vibrons in α-N2 was determined through analysis of the beating patterns, with a 0.005 cm-1 accuracy. A decrease of this splitting is observed with increasing temperature towards the α-β phase transition. © 1990.
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页码:423 / 425
页数:3
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