Spatiotemporal imaging of valence electron motion

Abstract

Electron motion on the (sub-)femtosecond time scale constitutes the fastest response in many natural phenomena such as light-induced phase transitions and chemical reactions. Whereas static electron densities in single molecules can be imaged in real space using scanning tunnelling and atomic force microscopy, probing real-time electron motion inside molecules requires ultrafast laser pulses. Here, we demonstrate an all-optical approach to imaging an ultrafast valence electron wave packet in real time with a time-resolution of a few femtoseconds. We employ a pump-probe-deflect scheme that allows us to prepare an ultrafast wave packet via strong-field ionization and directly image the resulting charge oscillations in the residual ion. This approach extends and overcomes limitations in laser-induced orbital imaging and may enable the real-time imaging of electron dynamics following photoionization such as charge migration and charge transfer processes.

Dissecting subcycle interference in photoelectron holography

“…Photoelectron vector momentum distributions (PMDs) encode these trajectories as intricate interference patterns displayed in angularly resolved photoelectron measurements. Significant work has been applied towards isolating and disentangling these patterns in order to determine the electron [2,[5][6][7][8][9][10][11][12][13][14][15][16][17] and sometimes the core [18][19][20] dynamics.…”

Femtosecond Laser Micro/Nano-manufacturing: Theories, Measurements, Methods, and Applications

“…Time-resolved transmissivities of induced region in fused silica detected using femtosecond laser with a 800-nm and b 400-nm probe pulses at different delay times. The linear relationship between electron density (c) and electron relaxation time (d) fits well with the theoretical predictions[38] Schematic of the time-resolved orbital imaging experiment and snapshots of a spin-orbit wave packet in the argon cation[39] 1 Demonstration of dual-energy electron beams and PIC simulations. Proposed radiation source and timing control based on dual-energy electron beams[40] Fig 12.…”

“…Experimental results of the electron relaxation time and electron density fit well with the theoretical predictions, thus validating the plasma model. Kübel et al [39] investigated the valence electron motion in argon ion with spatiotemporal imaging based on ultrafast pumpprobe technology ( Fig. 10).…”

Quantum interference and imaging using intense laser fields

“…Moreover, exploiting the intrinsic delay between ionization and rescattering, LIED can be seen as a pump-probe experiment, which has been used to probe nuclear motion not only in diatomic [22] but also polyatomic molecules [23,24]. Finally, electron diffraction without rescattering can probe electronic structure [21] and dynamics [25].…”