Knowledge Bank

We have observed with a Bruker 120 Fourier transform spectrometer the $Ar+$ emissions from the positive column of a glow discharge in a Ar/He(1/100) mixture. It was found that the $Ar+$ emission lines exhibit two distinct Doppler shifts (one an order of magnitude greater than the other), which we characterize as large” and small”. Experimentally, the emissions from levels with energies the excitation energy of $23S$ He) have large” doppler shifts while those with $E>E^{\prime}$ have small” ones. Our analysis leads one to believe that the emissions with large” Doppler shifts result from excitation of ground state $Ar^{+}$ via the reaction $He(2^{3}S)+Ar^{+}(3p^{5} \ ^{2}P^{3/2})$, while the emissions with Small” shifts arise from $Ar+$ levels excited directly by electron impact on neutral Ar.