Anomalous isotopic effect on electron-directed reactivity by a 3-μm midinfrared pulse

We have theoretically studied the effect of nuclear mass on electron localization in dissociating H-2(+) and its isotopes subjected to a few-cycle 3-mu m pulse. Our results reveal an anomalous isotopic effect in which the degree of electron-directed reactivity can be even higher for heavier isotopes in the intense midinfrared field. We show, for the first time, the pronounced electron localization can be established through the interferences among the multi-photon coupling channels. Due to the relative enhancement of higher-order coupling channels with growing mass, the interference maxima at different kinetic energy of the spectra gradually become in phase, ultimately resulting in the larger dissociation asymmetries of heavier isotopes. (C) 2013 Optical Society of America