中文摘要：

在532nm和177nm双色激光场的作用下，实现了对丙酮分子电离解离产物产额的调制．进一步，当激光焦点位置与分子束中心位置有一定偏离时，由于Gouy位相的影响，使得不同产物调制曲线之间产生位相差，实现了不同反应通道分支比的调控．在不同激光焦点与分子束中心相对位置处测得的不同位相差与根据特定反应通道模型进行的理论预期符合的很好，从而说明了丙酮分子的反应控制机制为：532nm三光子处发生解离产生乙酰基和甲基碎片被进一步电离，三光子处的激发态分子可以继续吸收两个基频光子而发生电离．

英文摘要：

Using bichromatic laser field of 532 nm and 177 nm, product yield from the ionization and dissociation of acetone is modulated. When the laser is focused away from the center of molecular beam, phase lags between the modulation curves of different products are observed, because of the effect of Gouy phase. The phase lag as a function of distance of molecular beam to laser focus agrees well with theoretical prediction based on specific reaction mechanism, which in turn elucidates the reaction control mechanism of acetone molecule to be： acetone molecule dissociates at three 532 nm photon level to give acetyl and methyl radicals which can be further ionized, the excited state molecule at three photon level can be ionized by absorbing two more 532 nm photons.