Near-Threshold Photodissociation of Cold CH1 in a Storage Ring

U. Hechtfischer,1 Z. Amitay,2 P. Forck,1 M. Lange,1 J. Linkemann,1 M. Schmitt,1 U. Schramm,1 D. Schwalm,1 R. Wester,1 D. Zajfman,2 and A. Wolf1 1Max-Planck-Institut für Kernphysik und Physikalisches Institut der Universität Heidelberg, 69029 Heidelberg, Germany 2Department of Particle Physics, Weizmann Institute of Science, Rehovot, 76100, Israel (Received 12 November 1997) Photodissociation of CH molecules (CH 1 hn ! C 1 H) is studied by collinear laser spectroscopy on a rotationally relaxed fast molecular ion beam in a storage ring. We have detected the resonances predicted between the thresholds related to the two fine-structure levels of the C fragment for low initial rotations, and found that no heating processes hinder the complete rovibrational thermalization of the fast stored beam in a room temperature environment. [S0031-9007(98)05681-6]