Application of the “helium excitation standard” procedure to some hydrocarbon Hβ absolute emission cross section measurements

Absolute emission cross sections for H_β radiation are presented. The H_β emission is obtained by dissociative electron excitation of propane, propylene, n-butane and 1-butene under binary collision conditions. Optical excitation functions measured for these 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 H_β radiation are not independent of the number of atoms in the parent molecule.