The role of mass in the carrier–envelope phase effect for H⁺₂dissociation

Abstract

The carrier–envelope phase (CEP) dependence of the dissociation of H+2 is studied with special emphasis on the role of the nuclear mass. We find that the total dissociation probability displays a CEP effect that grows with increasing mass, while the difference between dissociating to p+H and H+p displays an effect that shrinks. Insight into the physical processes involved is given by an analytic description that casts CEP effects as interferences between pathways requiring different numbers of photons.

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

“…(i) The asymmetry for the 800-nm pulse displays a CEP dependence that decreases with growing mass. This is coincident with the results of the previous studies [20]. But curiously, the asymmetry for the 3000-nm pulse shows an inverse isotopic behavior in which the degree of the asymmetry is even higher for heavier isotopes.…”

“…Meanwhile, for extending the control scheme to the larger molecules, the influence of nuclear mass on the reactions must be taken into account. However, it remains unclear how the nuclear mass affects the control efficiency when the midinfrared pulses are applied, though it has been shown that the control of electron localization is weakened by the growing mass in the few-cycle near-infrared field [9,20] To understand the influence of mass in reactions, the use of isotopes is one of the practice means. This is because different isotopes of a given element have a similar electronic structure and chemical properties, but different masses.…”

Carrier-Envelope Phase Control over Pathway Interference in Strong-Field Dissociation ofH2+

“…2(c) as a function of CEP. These oscillatory data were fit to the predicted dominant behavior [29,44,45] A(φ) = αcos(φ + φ 0 ) -where α is the asymmetry amplitude and φ 0 an offset. For the higher KER region, α is plotted for several cones about the polarization axis, indicated by ∆cosθ in Fig.…”

“…The origin of the CEP oscillations in the asymmetry can be understood within the theoretical framework proposed by Esry and coworkers [28,29,33,44,45]. In this theory, the spatial symmetry is broken through the interference of pathways involving different net numbers of photons that lead to opposite parity states.…”

“…Starting from an incoherent population of vibrational levels in the 1sσ g state of H + 2 (generated by electron-impact ionization in the ECR), dissociation of H + 2 occurs through laser-induced coupling to the 2pσ u state. If any single vibrational level dissociates via different pathways by absorbing and/or emitting different net numbers of photons with the same final energy, then the resulting even and odd nuclear parity states interfere, giving rise to a spatial asymmetry [28,29,33,44,45]. The dominant interference is through pathways where the net photon number differs by one, which leads to the predicted cos(φ + φ 0 ) dependence of the asymmetry [29,44,45] and fits our data well, as shown in Fig.…”