Chirp control of the formation of excited neutral D fragments in intense ultrafast laser pulses*

Excited neutral D fragments ($n$$\geq$2) are formed by the interaction of intense laser pulses with D$_2$ molecules [1]. One of the suggested interpretations of this process is that one (or both) of the electrons that were ejected recombine with the parent ion(s) and form the excited neutral fragment(s) [1]. In the present study, 400 nm laser pulses were used, and a single-prism pulse compressor [2] was implemented, which allows the generation of both positively- and negatively-chirped laser pulses. The kinetic energy release spectrum of neutral D fragments is observed to be extremely sensitive to the laser parameters. In particular, we report control of this spectrum using the chirp of the laser pulses. \\ {[1]} T. Nubbemeyer \emph{et al.}, Phys. Rev. Lett \textbf{101}, 233001 (2008). \\ {[2]} Selcuk Akturk \emph{et al.}, Opt. Express \textbf{14}, 10101 (2006).