Fano plot of the Paschen line of the excited hydrogen atom (n = 4) produced in e-H2 collisions Original Research Article

The Paschen α line (1875.1 nm) of the excited hydrogen atom (4s,4p,4d,4f) produced in e-H2 collisions was observed with a grating spectrometer equipped with a PbS detector. The emission cross sections were determined for the electron energy of 100–1000 eV, and were about half as much as those of the Balmer β line of the excited hydrogen atom (4s,4p,4d). The Fano plot indicated that the Paschen line was excited mainly through optically allowed processes as in the case of the Balmer lines.