A new laser spectroscopic technique has been demonstrated for examining the structure of alkali--rare gas diatomic electronic states near the classical limit. In two-color experiments, Rb--Ar or Rb--Kr thermal pairs are excited by free
leftarrowfree or bound
leftarrowfree transitions while monitoring the amplified spontaneous emission produced on the Rb D
1 or D
2 lines. Spectra observed lying within 10 cm
−1 of the separated atom limit for the A
2Pi1/2 states of Rb--Ar and Rb--Kr will be presented and discussed.
A two color process for optical pumping of the Rb D2 line laser (λ = 780 nm) in Rb vapor-rare gas mixtures is demonstrated to yield an overall quantum efficiency > 1. Combining photoexcitation of the Rb D2 line blue satellite in Rb-Xe or Rb-Ar mixtures with free ← free optical pumping of the A2Π12←X2Σ12+ transition at large internuclear separation (R > 5 Å) also increases the laser efficiency and pump absorption coefficient, relative to the single color, B ← X pumped system, by a factor of 1.7 and more than an order of magnitude, respectively. Simultaneous photopumping of Rb-Xe thermal collision pairs at 760 nm (D2 satellite) and 794.3 nm results in a 780 nm (D2 line) laser with a quantum efficiency of 1.008 which corresponds to the removal of ∼102 cm–1 (12.6 meV) of thermal energy per emitted photon.
We describe a series of measurements of absorption and laser induced fluorescence on cells that contained cesium and rubidium and a rare gas: He, Ar, Kr, or Xe. These studies showed strong blue wing absorption to the short wavelength side of the alkali atom D2 lines due to collisionally formed Cs- or Rb-rare gas excimers. We also have observed an efficient two photon excitation of higher lying states in Cs and Rb that produces both intense blue emission and IR atomic emission in the 1.3 to 3.8 μm spectral region.