Carrier-Envelope-Phase Dependent Dissociation of Hydrogen

Abstract

We studied dependence of dissociative ionization in H2 on carrier-envelope phase (CEP) of few-cycle (6fs) near-infrared (NIR) laser pulses. For low-energy channels, we present the first experimental observation of CEP dependence for total dissociation yield and the highest dwgree of asymmetry reported to date (40%). The observed modulations in both asymmetry and total yield could be understood in terms of interference between different n-photon dissociation pathways - n and (n+1) photon channels for asymmetry, n and (n+2) photon channels for yield - as suggested by the general theory of CEP effects (Roudnev and Esry, Phys. Rev. Lett. 99, 220406 (2007), [1]). The yield modulation is found to be Pi-periodic in CEP, with its phase strongly dependent on fragment kinetic energy (and reversing its sign within the studied energy range), indicating that the dissociation does not simply follow the CEP dependence of maximum electric field, as a naive intuition might suggest. We also find that a positively chirped pulse can lead to a higher dissociation probability than a transform limited pulse.

8 pages, 3 figures

References in corpus (2)

• Unitary theory of laser Carrier-Envelope Phase effects
• Nuclear classical dynamics of H${}_2$ in intense laser field

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• Phase- and intensity-dependence of ultrafast dynamics in hydrocarbon molecules in few-cycle laser fields
• Zero-energy proton dissociation of H${}_2^{+}$ through stimulated Raman scattering