Controlling strong-field fragmentation of H2+by temporal effects with few-cycle laser pulses

Abstract

In a joint experimental and theoretical endeavor, we explore the laser-induced dissociation and ionization dynamics of H${{}_{2}}^{\phantom{\rule{-0.16em}{0ex}}\phantom{\rule{-0.16em}{0ex}}+}$ beams using sub-10-fs, 800 nm laser pulses. Our theory predicts considerable control over the branching ratio of two-photon and three-photon above-threshold dissociation (ATD) by gating the dissociation pathway on a few-femtosecond timescale. We are able to experimentally demonstrate this control. Moreover, our theory also shows the importance of the highly excited H(2$l$) states of H${{}_{2}}^{\phantom{\rule{-0.16em}{0ex}}\phantom{\rule{-0.16em}{0ex}}+}$ that contribute to ATD structure in dissociation. As is the case for dissociation, we find that ionization is also sensitive to the effective laser interaction time.