Observation of laser-induced field-free permanent planar alignment of molecules

Md. Z. Hoque (1) , M. Lapert (1) , E. Hertz (1) , F. Billard (1) , Dominique Sugny (1) , B. Lavorel (1) , O. Faucher (1)

1 ICB - Laboratoire Interdisciplinaire Carnot de Bourgogne

Permanent planar alignment of gas-phase linear molecules is achieved by a pair of delayed perpendicularly polarized short laser pulses. The experiment is performed in a supersonic jet, ensuring a relatively high number density of molecules with moderately low rotational temperature. The effect is optically probed on a femtosecond time scale by the use of a third short pulse, enabling a time-resolved birefringence detection performed successively in two perpendicular planes of the laboratory frame. The technique allows for an unambiguous estimation of the molecular planar delocalization produced within the polarization plane of the pulse pair after the turn-off of the field. The measurements are supported by numerical simulations which lead to the quantification of the observed effect and provide more physical insights into the phenomenon.

Keywords: Molecular alignment; Femtosecond phenomena; Ultrafast nonlinear optics; Optical Kerr effect; Rotational dynamics; Optical polarigraphy

Domains: Atomic Physics [physics.atom-ph]

Md. Z. Hoque, M. Lapert, E. Hertz, F. Billard, Dominique Sugny, et al.. Observation of laser-induced field-free permanent planar alignment of molecules. Physical Review A : Atomic, molecular, and optical physics [1990-2015], 2011, 84 (1), pp.013409-1. ⟨10.1103/PhysRevA.84.013409⟩. ⟨hal-00639266⟩