Angular Selection of Products by Use of Saturated‐Absorption Techniques in the Cs(7P)+H2→CsH+H Reaction

The Cs( 7 P)+H 2 → CsH + H reaction is studied in a crossed-beam experiment with laser-inducedfluorescence detection of CsH products. The usual flux ( ≈ 50 mW / mm 2 ) which is delivered by the C.W.tunable dye laser used in the experiment is enough to saturate the absorption by CsH products. Then, bycrossing twice the laser beam through the collision volume (counterpropagating beams), one realizes theconditions of saturated-absorption experiments: when the laser frequency is tuned to a resonancefrequency of CsH products, a defect to absorption occurs for these products which scatter in the collisionplane and a "saturation dip" appears at the center of the corresponding fluorescence profile. Applicationof this technique to crossed-beam experiments can lead to the selection of product molecules which scatterin any definite plane. A different geometry of the laser beams (bent beams) is proposed to select moleculeswhich scatter in any definite direction: it could be applied to detect an asymmetry in the scattering of theproducts with respect to the collision axis, when a particular preparation of the reagents is realized.