PHOTODISSOCIATION OF ICI MOLECULE ORIENTED BY AN INTENSE ELECTRIC-FIELD - EXPERIMENT AND THEORETICAL-ANALYSIS

The idea of orienting molecules by applying an intense electric field on a rotationally very cold molecular beam has been introduced in 1990 by Loesch and Remscheid (J. Chem. Phys. 1990, 93, 4779) and also by F riedrich and Herschbach (Z. Phys. D 1991, 18, 153). Here we describe a n experiment in which the orientation thus produced in ICl molecules i s tested by a photodissociation experiment. The paper discusses the or ientation process with emphasis on the effects nonlinear in the applie d electric field. The characterization of the oriented beam and the ex periment will be briefly described. A complete simulation leads to a v ery good fit of the observed signal, but the rotational temperature de duced from this fit is higher than given by a direct measurement, the discrepancy being due to the presence of van der Waals complexes. This experiment has provided the first direct measurement (Clem. Phys. Let t. 1995, 244, 195) of the sign of the dipole of ICl (I(+)C1(-) as expe cted) and 3 measurement of the strong orientation achieved.