INVESTIGATIONS OF COLLISION DYNAMICS AND EXCITATION CROSS SECTIONS FOR He+ (1snp) 1P0 STATES (n=2-5) BY INTERMEDIATE AND HIGH VELOCITY ELECTRON, PROTON, AND MOLECULAR ION (H2+ AND H3+) IMPACT USING EUV SPECTROMETRY H. Merabet*, M. Bailey*, R. Bruch*, S. Bliman$, A. Siems#, A. G. Trigueiros#, D. V. Fursa@ and I. Bray@ *Department of Physics, University of Nevada Reno, Reno NV 89557 USA $Department de Physique, Universiti de Marne la Vallie, 93l66 Noisy LeGrand, France #Quantum Electronic Department, Physics Institute- UNICAMP, Campinas, Brazil @Electronic Structure of Materials Centre, The Flinders, University of South Australia, GPO Box 2100, Adelaise 5001, Australia A comprehensive study of helium excitation cross sections in the extreme ultraviolet (EUV) range following electron, and H+,H2+, and H3+ ion impact is given for He (1snp) 1Po states with n=2-5. These measurements extend over a large velocity range from 1.4 to 8.5 a.u. and represent the most complete data set obtained so far in the EUV. Furthermore, a comparison of all experimental and theoretical data including our new close convergent coupling calculations for the excitation of He (1snp) 1Po by e- + He collisions is provided.