Orienting and aligning molecules for stereochemistry and photodynamics

Abstract

Production, characterization and control of polarization states of molecules (specifically, alignment and/or orientation) are of importance for investigating in detail the stereodynamics of elementary processes involving elastic, inelastic and reactive events and also to prepare targets for selective photodynamical investigations. The focus here is on those molecular beam techniques which show perspectives in the applications offering appealing features for "duty cycle" and intensity characteristics. After a review of the basic experimental advances, mainly obtained in the last ten years, the attention will be addressed to recent studies carried out on the collisional alignment of hydrocarbon molecules and on orientation of symmetric top molecules by exploiting honeycomb hexapole fields. The first case is a prototype of "natural" polarization techniques, the second one of those where polarization is "forced" by external fields.

Rotational dynamics of an asymmetric-top molecule in parallel electric and nonresonant laser fields

“…The availability of oriented molecules provides a wealth of intriguing applications in a variety of molecular sciences, such as in chemical reaction dynamics [1][2][3][4][5], photoelectron angular distributions [6][7][8], or high-order harmonic generation [9][10][11]. An oriented molecule is characterized by the confinement of the molecular fixed axes along the laboratory fixed axes and by its dipole moment pointing in a particular direction.…”

Observed Molecular Alignment in Gaseous Streams and Possible Chiral Effects in Vortices and in Surface Scattering

“…References have been listed in Aquilanti et al (2005), where progress is described on how to improve hexapole electrostatic stateselectors, which are frequently employed to study the stereodynamics in chemical reactivity, such as reactive gas-phase scattering, surface scattering, photodissociation, and electron scattering. Applications have also been listed in Aquilanti et al (2005).…”

“…Some recent achievements in experimental techniques for controlling the spatial orientation of molecules [see the reviews Aquilanti (2005); Aquilanti et al (2005)] represent, for the time being, tools for investigations of the basic mechanisms, but perspectives are open to also exploit them for applied purposes in chemical stereodynamics.…”

Vector correlations in the F + HO → HF + O reaction and its isotopic variant

“…For elucidating the stereodynamics of a chemical reaction, QCT is proved to be one of the most popular methods. The QCT code capable of exploring vector properties in a chemical reactive system from Han's group, as well as those from other research groups [13][14][15][16], has been widely employed for the study of chemical reactions [17][18][19][20][21][22][23][24][25][26][27][28]. Both the scalar and vector properties, including product rovibrational distribution, translational distribution, angular distribution, PDDCS (polarization dependant differential cross section), product alignment and orientation parameters can be produced from the corresponding QCT calculations.…”