Evidence for high-l rydberg states in atomic lithium excited by electron impact

A.J. Smith

G. D. Stevens, M. T. Widmer, F. Tudorica +2 more

C. Chen, Xiao-Feng Han

Carl A. Kocher, C.L. Shepard

The distribution of principal quantum numbers for high-Rydberg states of lithium, produced in a thermal atomic beam by electron impact excitation, has been determined after passage of the beam through gaseous targets. Target densities were selected for an approximately tenfold reduction of the on-axis flux of Rydberg atoms. The state distribution, determined by electric field ionization, is markedly affected by a target of rapidly rotating polar molecules having rotational energy level separations comparable to the binding energy of the Rydberg valence electron. However, the distribution is not appreciably influenced by rare-gas or slowly rotating polar molecular targets, for which the Rydberg beam spreads as a result of momentum transfer.

M. Kent Ballard

Stephen J. Buckman, P. R. Hammond, Frank H. Read +1 more

By measuring the yield of metastable atoms resulting from electron-impact excitation of helium, in the range of incident electron energy from 19.8 to 24.6 eV, the authors have obtained evidence for He- resonances in which both the excited electrons have high values of the principal quantum number. The resonances occur in distinct groups, the lower members of which form Rydberg series characterised by effective core charges that are nonintegral. Classification schemes for these resonances are discussed.