THE 3d-3p ENDOTHERMIC COLLISIONAL POPULATION TRANSFER OF Li IN He AND Ar AT 298K Nobuaki Yonekura*, Takashi Nakajima#, Qin Hui+ and Michio Takami+ *Faculty of Science, University of the Ryukyus, Okinawa 903-0213, Japan # Institute of Advanced Energy, Kyoto University, Kyoto 611-0011, Japan + The Institute of Physical and Chemical Research (RIKEN), Saitama 351-01, Japan The 3p state of Li produced by the laser ablation was excited in He and Ar at 298 K and the time profiles of sensitized fluorescence from the 3s state were measured. The 3d<-3p endothermic population transfer rates determined from the pressure dependence of the time profiles were 6.5x10-11 cm3s-1 for He and less than 10-13 cm3s-1 for Ar.