VUV excitation of a vibrational wavepacket in D₂measured through strong-field dissociative ionization

Abstract

Femtosecond vacuum ultraviolet pulses from a monochromated high harmonic generation source excite vibrational wavepackets in the B 1 g S + state of D 2 . The wavepacket motion is measured through strong field ionization into bound and dissociative ion states yielding D 2 + and D + products. The time dependence of the D 2 + and D + ion signals provides a sensitive fingerprint of the quantum nuclear wavepacket, due to the different ionization rates for the two channels. The experiments are modelled with excitation and ionization processes included explicitly, with the results of the model showing a very good agreement with the experimental observations. The experiment demonstrates the level of detail attainable when studying ultrafast quantum nuclear dynamics using high harmonic sources.

Fundamental Limits on Spatial Resolution in Ultrafast X-ray Diffraction

“…Due to the anharmonic nature of the potential, the wavepacket gradually spreads across the entire B-state potential. It is worth emphasizing that this wavepacket has been observed in a recent experiment using a strong-field probe [27].…”

“…The pump pulse energy is 14.3 eV, with the full width at half maximum (FWHM) duration 20 fs, such that the excited vibrational wavepacket is centered at the ν = 38 vibrational state [27]. The potential energy curves are shown in Figure 1a.…”

“…Depending on the experimental situation, the wavepacket may be of electronic [25,26], nuclear [27], or mixed nuclear-electronic [28] nature. Inevitably, the localization of the initially prepared wavepacket and its subsequent spreading depends not only on the potential energy landscape of the molecular system but also on the exact optical preparation of the initially excited state [29][30][31].…”

Monte Carlo wave-packet approach to trace nuclear dynamics in molecular excited states by XUV-pump–IR-probe spectroscopy

“…Apart from controlling electron localization, this XUV-IR scenario is especially useful in monitoring the nuclear dynamics in molecular excited states. For example, this scenario was applied to characterize the singly excited molecular dynamics by using the ionization signal [14][15][16].…”

“…[14][15][16]) only the single-ionization channel is open, which limits the information about the ultrafast dynamics obtained by the measurements. More information can be obtained if double-or multiple-ionization channels are open.…”