Resonant Formation of Ca+ From the Ca+ (4s25d1d2) level explained by autoionization through the 3d3/29f3/2Jπ=2 resonance

Published

August 1, 1996

Author(s)

Henrik Q. Lorensen, Harold V. Parks, E M. Spain, J E. Smedley, C H. Greene, S R. Leone

Abstract

The formation of Ca+ ions is measured in an effusive Ca beam by exciting through either the 4s4p¹P₁ state to highly excited Ca*(4snd^1d2) Ryberg states. In agreement with previous work by McLaughlin and Duguette, when the Ryberg states are accessed through the 4s5p¹P₁ state, we detect a larfe increase in Ca+ ions for n=25, compared to other high n Ryberg states. It had been reprorted [Fabrikant; McLaughlin and Duguette] that ground stat-Ryberg state collisions cause this large increase in ion production and that the result provides a precise value of the electron affinity of Ca through the binding energy of the Ryberg electron. However, a variation of the origional experiment in which the same Ryberg states are accessed through the 4s4p¹P₁ level instead of the 4s4p¹P₁ level shows no enhancement of ions for any particular Ryberg level. With a three-laser experiment we show that the enhanced ionization effect for the 25d state is due to the 3d_3/29f_3/2J^π=2 autoionizing resonance, which is coincidentally accessed from the Ca(4s25d^1d2) state by the 808 nm photon involved in the original experiment by McLaughlin and Duquette. The existance of this resonance close to the experimentally observed energy is also established by R-Matrix calculations.

Citation

Physical Review A (Atomic, Molecular and Optical Physics)

Volume

54

Issue

No. 2

Pub Type

Journals

Keywords

autoionizing, calcium, electron affinity, Rydberg state

Citation

Lorensen, H. , Parks, H. , Spain, E. , Smedley, J. , Greene, C. and Leone, S. (1996), Resonant Formation of Ca+ From the Ca+ (4s25d^1d2) level explained by autoionization through the 3d_3/29f_3/2J^π=2 resonance, Physical Review A (Atomic, Molecular and Optical Physics) (Accessed October 14, 2025)