Spatial alignment of gas-phase polyatomic molecules by an intense laser field

Abstract

Angular distributions have been measured of Cl${}^{+}$ fragment ions resulting from dissociative ionization of polyatomic molecules CCl${}_{4}$, CHCl${}_{3}$ and CH${}_{2}$Cl${}_{2}$ induced by linearly polarized laser pulses of intensity 10${}^{13}$ W cm${}^{\ensuremath{-}2}$. Pronounced anisotropy is exhibited in all cases, with Cl${}^{+}$ detected mainly along the direction of the laser's polarization axis, indicative of field-induced spatial alignment of the precursor molecules. The directional properties of the average linear polarizability of the precursors appear to play a key role in determining the extent to which such alignment occurs.