Generation, characterisation, and applications of atomic and molecular alignment and orientation

Abstract

The gas phase is generally defined as a state of matter in which atoms or molecules are in constant, rapid, random Brownian motion. However, a range of techniques exist for preparing distributions of gas phase atoms and molecules whose motion is far from random, and whose orientation in space is well defined. In this Perspective, we will explore the nature of atomic and molecular alignment and orientation, the various techniques by which samples of spatially oriented species may be prepared and characterised, and some of the ways in which oriented molecules are being exploited to further our knowledge of molecular structure and dynamics.

Role of Rotational Wave Packets in Strong Field Experiments

“…Impulsive alignment of linear molecules [1] has been applied in the past decades to a wide range of applications, spanning from femtochemistry [2] to strong field experiments [3][4][5][6]. In this last framework, it opened the possibility to conduct field-free experiments in the molecular frame of reference and has been a crucial requirement to resolve molecular structure [7,8] and dynamics [9] using, for instance, high harmonic generation (HHG) spectroscopy or laser induced electron diffraction [10].…”

Field-free molecular alignment control by phase-shaped femtosecond laser pulse

“…8 A strong linearly polarized laser pulse was considered as the most effective method to realize the molecular alignment, where the molecule is aligned along the laser polarization direction. [9][10][11][12] The laser-induced molecular alignment can be obtained in non-adiabatic or adiabatic regimes that depend on the laser pulse duration. 13 In adiabatic process, i.e., the laser duration is much larger than the rotational period of the molecule, the molecular alignment is maximally obtained during the interaction with the laser pulse, and will disappear when the laser is off.…”

Dynamical coupling of molecular rotation and Coulomb explosion

“…Field free molecular rotational alignment is nowadays a routine technique to achieve structural and dynamical measurements in the molecular frame [1]. It is a unique tool to study electron recollision in strong field physics as in High Harmonic Generation (HHG) spectroscopy and recollision-induced double ionisation and fragmentation.…”