High Resolution (6-12 meV) Threshold Photoelectron Spectroscopy of Argon
from 28 to 49 eV

M.C.A. Lopes(1,2), A.J. Yencha(3), G.C. King(1), J.D. Bozek(4), N. Berrah(5)

(1) Manchester University
(2) Universidade Federal de Juiz de Fora
(3) University at Albany
(4) Lawrence Berkeley National Laboratory
(5) Western Michigan University

We have measured the threshold photoelectron (TPE) spectrum of argon at high
resolution (6-12 meV) using synchrotron radiation on beamline of the
Advanced Light Source over a wide spectral range (28-49 eV) encompassing the
(3s)-1 Ar+ main line, the entire associated satellite ionization region, and
the onset region of the doubly ionized Ar states 3P, 1D and 1S.  Numerous new
satellite ion and neutral resonances have been detected and analyzed.