FEMTOSECOND LASER PHOTOELECTRON SPECTROSCOPY ON ATOMS AND SMALL MOLECULES: Prototype Studies in Quantum Control

Abstract

We review prototype studies in the area of quantum control with femtosecond lasers. We restrict this discussion to atoms and diatomics under gas-phase collision-free conditions to allow for a comparison between theory and experiment. Both the perturbative regime and the nonperturbative regime of the light-matter interaction are addressed. To that end, atomic/molecular beam techniques are combined together with femtosecond laser techniques and energy-resolved photoelectron spectroscopy and ion detection. Highly detailed information on the laser-induced quantum dynamics is extracted with the help of kinetic energy-resolved photoelectron spectroscopy.

Strong field quantum control by selective population of dressed states

“…Due to the off-resonant excitation and the reduced resolution of the photoelectron spectrometer for very low photoelectron energies, the fringes are not seen in the slow photoelectrons. Since the photoelectron spectrum maps the population of the dressed states [5], the experimental results demonstrate the preferential population of one dressed state during the excitation/ionization process. Apparently, the selectivity is controlled by the relative phase of the second laser pulse via the delay.…”

“…Quantum control deals with the design of suitably shaped light fields to selectively steer quantum systems from an initial state to a desired final state with high efficiency. Many quantum control strategies have been proposed and demonstrated experimentally which are summarized in recent reviews [1][2][3][4][5].…”

Monitoring the Birth of an Electronic Wavepacket in a Molecule with Attosecond Time-Resolved Photoelectron Spectroscopy

“…In this, the pump pulse should be in the UV domain and no longer than a few femtoseconds (not to trigger the nuclear motion), while the probe pulse should be even shorter in order to observe the electronic motion with high-enough time resolution. The method of choice would thus be time-resolved photoelectron spectroscopy [24][25][26][27][28][29][30] using an attosecond XUV probe pulse.…”

Molecular events in the light of strong fields: A light‐induced potential scenario

“…[1][2][3][4][5] Initially, ultrashort pulses were used because they provided the means to act on the time-scale of fast molecular events. [6] At a later stage, it was the broad pulse spectrum of the pulses that by phase modulation and learning algorithms, opened great opportunities to control the dynamics.…”