Direct observation of effective temperature of Ta atom in layer compound TaS2 by neutron resonance absorption spectrometer

A neutron resonance absorption spectrometer, DOG, has been installed at KEN S, High Energy Accelerator Research Organization Neutron Source, which enab les us to investigate the motions of a particular element by analyzing the line width of resonance absorption spectrum. We measured the temperature de pendence of the effective temperature of Ta motion in TaS2 as well as in Ta metal using DOG. The effective temperatures extracted from the observed ab sorption spectrum agree well with the calculated values from the phonon den sity of states of Ta metal over a wide temperature range of 10 to 300 K. We also succeeded in measuring both the angular dependence and the temperatur e dependence of effective temperatures of Ta in a layer compound TaS2. Base d on the temperature dependence of the effective temperature, the partial p honon density of states of Ta in TaS2 was discussed.