Statetostate integral cross sections for the inelastic scattering of CH(X 2Π)+He: Rotational rainbow and orbital alignment J. Chem. Phys. 91, 821 (1989); 10.1063/1.457134Rotationally inelastic collisions of LiH with He. III. Experimental determination of statetostate cross sections State-to-state differential cross sections for rotational transitions of Na2 in collisions with He are measured in the electronic and vibrational ground state at thermal collision energies using a new laser technique. Single rotational levels Ji are labelled by modulation of their population via laser optical pumping using a dye laser. The modulation of the fluorescence induced by an Ar+ laser tuned to the level J = 28 is proportional to the cross section for collisional transfer J .. ~jf and is detected at the scatte~ng angle -3. A single optical fiber and a fiber bundle provide a flexible connection between the detector and the laser and photomultiplier, respectively. Transitions as large as ~j = 20 are observed. At small angles elastic scattering is dominant, but rotationally inelastic processes become increasingly important at larger scattering angles. Rotational rainbow structure causing a steep onset of the cross section with the scattering angle -3 (at fixed ~j) ora sharp cutoff with ~J (at fixed -3) is found. Preliminary results on rotational energy transfer in v = I indicates that vibrational motion of the molecule favors larger rotational quantum jumps.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.