HEXAPOLE STATE SELECTION AND FOCUSING VS BRUTE FORCE ORIENTATION OF BEAM MOLECULES

The commonly used method of orienting polar molecules in a beam, by st ate selection and focusing with an electrostatic hexapole lens, is com pared with the recently introduced orientation method by means of a st rong, homogeneous, electric field, based on second- and higher-order S tark effects. The latter, so-called brute force orientation technique, has proved much more effective than had been assumed until recently, and increasingly so ii the beam molecules are rotationally very cold. The properties of both techniques are illustrated by a number of examp les. The wider applicability and technically simpler implementation of the brute force orientation technique is offset by the absence of sta te selection. For the description of the molecular orientational distr ibution this means that, in general, more parameters are needed than f or a molecule selected in a single quantum state.