Laser-induced fragmentation of D$_{2}$: detection of metastable D$^{\ast}$ atoms

In a recent Letter, Manschwetus \textit{et al.} [Phys. Rev. Lett. \textbf{102}, 113002 (2009)] reported experimental evidence for the formation of metastable H* fragments upon dissociative ionization of H$_{2}$ by a strong laser field. Their finding was explained using a frustrated tunnel ionization model. Here, we present our measurements of D* formation from D$_{2}$ that encompass the dependence of this process on pulse duration, intensity, ellipticity and angular alignment. We find that the mechanism suggested by Manschwetus \textit{et al.} is consistent with our experimental data. However, other mechanisms might also be consistent with the data. A few possible mechanisms have been eliminated by our theoretical work on the fragmentation of the transient D$_{2}^{+}$, and further investigation of other mechanisms is underway. Supported by the Chemical Sciences, Geosciences and Biosciences Division, Office of Basic Energy Sciences, Office of Science, U.S. Department of Energy.