Application of the 'helium excitation standard' procedure to some hydrocarbon Hsub(β) absolute emission cross section measurements

Absolute emission cross sections for Hsub(β) radiation are presented. The Hsub(β) emission is obtained by dissociative electron excitation of propane, propylene, n-butane and 1-butene under binary collision conditions. Optical excitation functions measured forthese transitions are normalized by the 'helium excitation standard, procedure, using the 4 1S-2 1P transition in He as a standard at an electron impact energy of 100 eV. The results obtained are determined with an accuracy of +- 15%. The investigated energy interval is 50-500 eV. The experimental results show that the emission cross sections for Hsub(β) radiation are not independent of the number of atoms in the parent molecule. (Auth.)