Ultrafast electron–nuclear wavepacket in ${\mathbf{O}}_{2}^{\mathbf{+}}$ generated and probed with attosecond pulse trains

Abstract

We observed the dynamical evolution of the electron–nuclear wavepacket composed of the and 32Πu states of with an evolution period of 1.3 fs. We created a dissociative wavepacket of by photoionization of O2 with the irradiation of an intense attosecond pulse train (APT) in the extreme ultraviolet (XUV) wavelength region, and probed it with another XUV APT by scanning delay between the two APTs. We revealed the evolution of the electron–nuclear wavepacket by the analysis of the spectral phase in the Fourier transform of the recorded delay dependent momentum spectrum of O+. We also found the correlation between the photon energy and the released kinetic energy originating from the dissociation of Rydberg states of O2 followed by the autoionization of the fragment O atom in the Rydberg states.

Attosecond technology(ies) and science

“…The high repetition rate creates the ability to achieve unprecedented signal-to-noise ratios in a plethora of investigations, as well as the implementation of attosecond experiments with coincident detection of all electrons and ions [15,119]. In addition, OPCPA enables the generation of attosecond pulses and pulse trains that are sufficiently intense to permit XUV pump-XUV probe experiments [120,121]. Moreover, the increased reliability of these systems enables scientists from other communities to benefit from attosecond technologies without themselves needing to be specialists of laser technology.…”

“…In the current special issue, in an example of attosecond XUV pump-XUV probe spectroscopy, Fukahori et al [120] report experiments on electron-nuclear wave packet dynamics in O 2 , using two time-delayed APTs. They measure the O + fragment kinetic energy distribution as a function of the delay between the two pulses, and observe out-of-phase 2ωoscillations at high and low fragment kinetic energy, which are interpreted in terms of probing (by the XUV probe laser) of an electron-nuclear wave packet consisting of the coherent superposition of two cationic electronic states (both produced by the XUV pump laser).…”