Intense-Laser-Field Ionization of the Hydrogen Molecular IonsH2+andD2+a

Abstract

Fragmentation of H2+ and D2+ in ion beams has been studied with short intense laser pulses (100 fs, I=5x10(13)-1x10(15) W/cm2) and by a high-resolution two-dimensional velocity imaging technique. In the Coulomb explosion channel, at intensities just above the threshold for this process, we observe a clear structure in the kinetic energy spectra not previously found or predicted. The peaks can be attributed to single vibrational levels. We interpret this observation as a dissociative allocation of the electron to a proton followed by enhanced ionization at a well-defined "critical" overstretched internuclear distance. When using longer pulses we observe three separate Coulomb explosion velocity groups corresponding to critical distances of about 8, 11, and 15 a.u.

Probing two-center interference in H2+using chirped pulses

“…A similar electronic quantum interference process was proposed as a mechanism for electron localization in dissociating H + 2 [6]. Structures in the KER spectra, taking the form of a sequence of peaks, were also observed in other related experiments [7,8]. The importance of multiple paths leading to the same final state becomes particularly pronounced in the ionization and dissociation dynamics of molecules, as the nuclear dissociative motion typically occurs on a completely different time scale than the electronic one.…”

Strong-field approximation for Coulomb explosion ofH2+andD2+Leth1, Madsen2, McCann3 2007Phys. Rev. A6050View full textAdd to dashboardCite

“…Given the equilibrium bond length of H + 2 is R = 2 a 0 , this suggests dissociation occurring prior to ionization. The increased probability of ionization with increasing R can be understood by the mechanism of resonantly-enhanced multiphoton ionization via the antibonding 2pσ + u state [7,8] when the resonances are tuned 'from the red' as the bond expands. Conversely, at very high intensities the ionization process can be characterized as a tunneling transition.…”

Nuclear interference in dissociating of HD+in ultrashort laser fields

“…During the past two decades, there have been considerable efforts to investigate the elementary molecules, such as H 2 , H 2 + (D 2 , D 2 + ), both theoretically and experimentally. They exhibit many exciting phenomena including bond softening and bond hardening (vibrational trapping) [1,2], above-threshold ionization (ATI) and dissociation (ATD) [3][4][5][6][7], charge resonant enhanced ionization and Coulomb explosion [8][9][10][11][12][13], electron "recollision" in molecular ionization [14][15][16], and electron localization in molecular dissociation [17][18][19][20] by varying the laser pulse parameters.…”