Electron impact excitation of 5p states of rubidium at 20 eV incident energy Jia Hou Chin, Kuru Ratnavelu and Yajun Zhou Eur. Phys. J. D, 68 6 (2014) 141 Published online: 05 June 2014 DOI: 10.1140/epjd/e2014-40689-2