Nabekawa Yasuo, Furukawa Yusuke, Okino Tomoya, Amani Eilanlou A, Takahashi Eiji J, Yamanouchi Kaoru, Midorikawa Katsumi
Attosecond Science Research Team, RIKEN Center for Advanced Photonics (RAP), 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan.
Department of Chemistry, School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-0033, Japan.
Nat Commun. 2015 Sep 1;6:8197. doi: 10.1038/ncomms9197.
The vibrational wavepacket of a diatomic molecular ion at the time of ionization is usually considered to be generated on the basis of the Franck-Condon principle. According to this principle, the amplitude of each vibrational wavefunction in the wavepacket is given by the overlap integral between each vibrational wavefunction and the ground vibrational wavefunction in the neutral molecule, and hence, the amplitude should be a real number, or equivalently, a complex number the phase of which is equal to zero. Here we report the observation of a non-trivial phase modulation of the amplitudes of vibrational wavefunctions in a wavepacket generated in the ground electronic state of a H₂⁺ molecular ion at the time of ionization. The phase modulation results in a group delay of the specific vibrational states of order 1 fs, which can be regarded as the settling time required to compose the initial vibrational wavepacket.
双原子分子离子在电离时的振动波包通常被认为是基于弗兰克 - 康登原理产生的。根据这一原理，波包中每个振动波函数的振幅由每个振动波函数与中性分子基态振动波函数之间的重叠积分给出，因此，振幅应该是一个实数，或者等效地，是一个相位等于零的复数。在此，我们报告了对H₂⁺分子离子基电子态在电离时产生的波包中振动波函数振幅的非平凡相位调制的观测结果。这种相位调制导致特定振动状态的群延迟约为1 fs，这可以被视为构成初始振动波包所需的稳定时间。
