Effect of ro-vibrational coupling on rotational wavepacket of N

Yokoyama, Atsushi; Akagi, Hiroshi; Kumada, Takayuki   ; Itakura, Ryuji; Hasegawa, Hirokazu*; Oshima, Yasuhiro*

Recently, we demonstrated a nitrogen isotope separation based on isotopically different time-evolution of rotational wavepacket by using N/N mixture, in which at first rotational wavepackets of isotopomers were created by the irradiation of a femtosecond laser pulse, then a specific isotopomer molecules were ionized by another femtosecond laser pulse at the time when they align. In the experiment, we found peak shapes of the N intensity were distorted as the evolution time passes. The behavior was not predicted by a rigid rotor model. In this work, we examined the effect of ro-vibrational coupling on this behavior by solving a time-dependent Schrdinger equation including the coupling. As a result, we elucidated that the simulation agreed well with the experimental results and that the effect of ro-vibrational coupling became larger as the rotational temperature increased.