Hg($^3P_1$)$-$CO HALF COLLISION INVESTIGATED BY ULTRASHORT LASER PULSES Kazuhiro Amano, Kenji Ohmori, Hisashi Chiba, Misaki Okunishi, and Yukinori Sato Research Institute for Scientific Measurements, Tohoku University, Sendai, Japan We have applied the ultrafast pump/probe approach to the Hg(6 $^3P_1)-$CO half collision to explore its dynamics that could never be extracted in the frequency domain.