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(-Δ<i>E/kT</i>), when the energy difference, Δ<i>E,</i> between the excited state and the ionization limit is increased. The ionization efficiencies are found to be close to unity for states with Δ<i>E</i> < <i>kT</i> and approximately 50% for states with Δ<i>E</i> ≈ 2.5 <i>kT</i> (<i>np</i> ≈ 6<i>p</i>). For the lower states, the ionization efficiencies are found to be approximately five times larger than the Boltzmann factor.

PDF Article

Cited By

You do not have subscription access to this journal. Cited by links are available to subscribers only. You may subscribe either as an OSA member, or as an authorized user of your institution.

Contact your librarian or system administrator
Login to access OSA Member Subscription