Strong field molecular ionization to multiple ionic states: direct versus indirect pathways

Abstract

Abstract. We present velocity map imaging measurements of photoelectrons in coincidence with ions produced via strong field molecular ionization. Our measurements, in conjunction with electronic structure and Stark shift calculations, allow us to assign several features in the low energy portion of the photoelectron spectrum to different molecular electronic continua (ionic states). Furthermore, we are able to distinguish between direct and indirect ionization pathways, uncovering the role of both neutral and ionic resonances in the ionization dynamics.

Time-resolved measurement of internal conversion dynamics in strong-field molecular ionization

“…The assignment of the peaks in Fig. 4 has been carried out in previous work and verified with electron-ion coincidence measurements [47]. The expected energies of the photoelectrons can be found from the energy conservation equation:…”

Strong Field Molecular Ionization in the Impulsive Limit: Freezing Vibrations with Short Pulses

“…Earlier work assigned these peaks to leaving the molecule in the first two states of the molecular cation: D 0 and D 1 , respectively. The assignment of the spec-trum to the molecular ions was verified using electronion coincidence spectroscopy [25]. While the yield from 0-0.2 eV and around 1.6 eV can be assigned to D 2 /D 3 [25], we focus on the yield to D 0 and D 1 for simplicity here.…”

“…The assignment of the spec-trum to the molecular ions was verified using electronion coincidence spectroscopy [25]. While the yield from 0-0.2 eV and around 1.6 eV can be assigned to D 2 /D 3 [25], we focus on the yield to D 0 and D 1 for simplicity here. Earlier work [28] also established that these peaks involve resonance enhancement via intermediate neutral states that Stark shift into resonance during the ionization process [29].…”

Ionic dynamics underlying strong-field dissociative molecular ionization

“…The experimental apparatus is very similar to that used in previous work [18]. Briefly, our light source is an amplified Ti:sapphire laser system, producing 30 fs (intensity FWHM) pulses centered around 780 nm, at a 1 kHz repetition rate.…”

“…Given the ionization potentials of the relevant states (see Table I), coincidence detection allows us to assign various peaks in the spectra to states of the ion because of the relationship between the photoelectron energy and the ionization potential at the moment of ionization (see Equation 1). We refer interested readers to previous work [18] for detailed methods used in assigning these peaks. Here we are mainly interested in the indirect ionization corresponding to those pairs of peaks at identical energies, one of which is measured in coincidence with the parent and the other with a fragment ion.…”