State-specific ionization efficiencies for excited Li and Na atoms in acetylene/air flames have been determined. The ionization efficiencies, i.e., the probability that the excited atoms ionize instead of returning to the ground state, are determined by relating collision-assisted Laser-Enhanced Ionization (LEI) signals from various excited states with laser-induced photoionization signals. The ionization efficiencies are found to decrease (from being one at the ionization limit) almost monotonically as the lower atoms are excited. The most striking feature, however, is that the decrease of the ionization efficiency values is generally found to be less than the decrease of the Boltzmann factor, exp(-ΔE/kT), when the energy difference, ΔE, between the excited state and the ionization limit is increased. The ionization efficiencies are found to be close to unity for states with ΔE < kT and approximately 50% for states with ΔE ≈ 2.5 kT (np ≈ 6p). For the lower states, the ionization efficiencies are found to be approximately five times larger than the Boltzmann factor.
O. Axner and T. Berglind, "Determination of Ionization Efficiencies of Excited Atoms in a Flame by Laser-Enhanced Ionization Spectrometry," Appl. Spectrosc. 43, 940-952 (1989)
References are not available for this paper.
OSA is able to provide readers links to articles that cite this paper by participating in CrossRef's Cited-By Linking service. CrossRef includes content from more than 3000 publishers and societies. In addition to listing OSA journal articles that cite this paper, citing articles from other participating publishers will also be listed.