VIBRATIONAL EXCITATION OF HBr BY ELECTRON IMPACT NEAR THRESHOLD Anne-Christelle Sergenton, Michael Allan, and Du=9Aka B. Popovic Institute of Physical Chemistry, University of Fribourg, Perolles, 1700 Fribourg, Switzerland Threshold peaks and structures in the cross sections for vibrational excitation of HBr by electron impact are investigated. It is found that the relative height of the threshold peak depends strongly on the final vibrational level and on isotope substitution. The results are compared to recent nonlocal potential theory of Domcke, Horacek, and Cizek.