J. J. Wynne

Spectroscopy of even-parity autoionizing levels in Ba.

Using multiphoton ionization spectroscopy, we have observed transitions in Ba from the 6s(2)(1)S(0) ground state to even-parity autoionizing states. We have seen extended series with J = 0, 1, and 2 of the type 5dnd and 5dns, converging on the 5d(2)D(3/2) and (2)D(5/2) ionization limits. A multichannel quantum-defect theory analysis of the J = 0 spectrum is presented.

Spectroscopy of 3 P 0 states of alkaline earths

Using multiphoton-ionization spectroscopy, we have observed transitions from the 1S0 ground states to the 4snp, 5snp, and 6snp3P0 states of the alkaline earth atoms Ca, Sr, and Ba, respectively. One-photon transitions from a 1S0 ground state to 3P0 states are spin-forbidden. We have identified these series in Ca and Sr up to n > 70, whereas previous efforts have failed to identify these series beyond n = 7. These series behave like nearly constant quantum-defect (δ) series with δCa = 1.97 and δSr = 2.90. Preliminary results for Ba, up to n = 60, indicate greater complexity.

Ionization studies in laser-excited alkaline-earth vapors.

We report on the time behavior of ionization signals produced by laser excitation of Ca and Ba atomic vapor to high-Rydberg states. A space-charge-limited thermionic diode detector shows a long-lived (>I-msec) ionization signal. However, optical detection of atomic ions (Ca+, Ba+) shows that these species live for much shorter times (<100 microsec). These results, in conjunction with published results on mass-spectrometric studies of high-density atomic beams, suggest that our ionization signal is primarily due to molecular species (Ca2+, Ba2+). We also observed optically pumped amplified spontaneous emission and stimulated electronic Raman scattering in Ca+ and Ba+.

Atomic Rydberg-state spectroscopy of Ca i using pulsed color-center lasers

The utility of using color-center lasers for atomic spectroscopy is demonstrated. Pulsed, color-center lasers are used in conjunction with pulsed dye lasers for multiphoton ionization spectroscopy studies of Ca I. The 4s6d(1)D(2)-4snf(1)F( masculine)(3) spectrum for n = 11-16 is observed. Two other series of lines are identified as 4s5f(1)F( masculine)(3)-4sng(1)G(4) and X-4sng(1)G(4) transitions.