Photodissociation dynamics of the CH3 radical at 212.5 nm excitation has been studied experimentally using the H atom Rydberg tagging time-of-flight method. CH3 radicals are produded by photodissociation of CH3I at 266 nm. Translational energy distribution and angular distribution for the CH2 product from CH3 photodissociation at different vibrational levels via the 3s Rydberg state have been measured. From these distributions, product J state distributions are obtained for photodissociation of different vibrationally excited CH3 radicals. The effect of parent vibrational as well as rotational excitation on the dissociation dynamics of CH3 is also investigated in detail. Experimental results in this work show that parent vibrational excitation in the umbrella mode has a significant effect on both rotational excitation and angular distribution of the CH2 product, while parent rotational excitation has obvious effect only on the angular distribution of CH2 product.
By using the home-made femtosecond laser system and the time-of-flight mass spectrometer, the decay dynamics of excited carbon disulfide (CS2) and ammonia (NH3) are investigated in real time by pump-probe mul-tiphoton ionization detection. The estimated lifetime constantof the NH3 A1A2 state (51±4 fs) agreed quite well with the literature report. For the first time, the decay lifetime constants of the NH3 E’1A’1, state (937±93 fs), the CS2 a3A2 state (153±10 fs), and the CS2 Rydberg state[3/2](3IIg) (948±23 fs) are obtained.
ZHANG Jianyang LIU Hongping, YING Shuhui, JIANG Bo, XU Dali, WANG Li & LOU NanquanState Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
