Laser action on the B2 SIGMA+1/2 --> X2 SIGMA+1/2 band of HgCl at 557.6 nm (v' = 0 --> v'' = 22) has previously been achieved under a variety of electronic and optical excitation mechanisms. This letter describes a chemical mechanism for producing excited HgCl. We report on the gas phase reaction between alkali atoms (K, Rb, and Cs) and HgCl2 which produces HgCl (B-X) emission.

Vapor phase reactions between alkali atoms and several halocarbon molecules containing C-C bonds have been observed to produce chemiluminescence which appears to originate from C2−- (alkali)+ complexes.

The reaction between alkali vapors and PSCl3 produces PS(B2Π → X2Π) chemiluminescence.

The gas phase reaction between alkali atoms and TeCl4 produces chemiluminescence from the A(0u+) state of Te2.

The gas-phase reaction between alkali atoms and SbCl 5 produces SbCl(A 1 → X 1 ) chemiluminescence from v ′ > 4 to v ″ > 6.

A simple model proposed by Baylis for treating the interaction of excited and ground-state alkali-metal atoms with multiple rare-gas perturbers has been applied to the calculation of peak wavelengths in the band emission of $\mathrm{K}(5s){\mathrm{Xe}}_{N}$ exciplexes observed by Yabuzaki et al. In addition, the binding energies of these exciplexes have been calculated and compared with experiment.

The gas phase reaction between a mixture of K and Na and CBr4 produces, under low-density conditions, emission from high-lying vibrational levels (υ′ > 9) of the B 1 Π state of NaK.

Existing data on Na-rare gas and rare gas–rare gas dimer potentials have been used in a computer program to simulate the formation of trapping sites for Na atoms isolated in Ar and Xe solids. The dimer potentials have also been employed to calculate the matrix perturbed energy-level structure of the Na atoms to obtain theoretical wavelengths for absorption and emission bands corresponding to the sites formed in the simulations. The results support the view that the stable blue-shifted absorption band of Na in Ar and Xe is due to a substitutional site and that the thermally unstable unshifted band results from amorphous sites evolving from two-atom vacancies. In all cases, the simulated sites exhibited a local symmetry sufficient to produce a degeneracy in the perturbed Na 3p state levels.

S2(B-X) chemiluminescence, primarily from ν′ = 0 and 1, has been observed in alkali atom—SCl2 reactions. The addition of He or Ar buffer gas to the reaction chamber alters the reaction dynamics, and at certain buffer gas pressures the S2 emission originates exclusively from the ν′ = 6–9 vibrational levels of the B(3Σu−) state.

A simple procedure is described for calculating the energy levels of an alkali atom perturbed by rare-gas neighbors in a solid rare-gas matrix, using alkali-rare-gas dimer potentials available in the literature. Straightforward analysis leads to an expression for the perturbation due to an arbitrary number of rare-gas neighbors in terms of alkali-rare-gas dimer potentials. The results of calculations for Na trapped in Ar are presented and compared with experiment and with earlier pseudopotential calculations.

Absorption and emission spectra of rubidium and cesium trapped in Ar matrices at 10°K are reported. (AIP)

Intense chemiluminescence in the wavelength range 4100–5500 A has been observed in diffusion flames of alkali vapor burning in C2Cl4 and C2F4. The emission spectrum is not consistent with the known emission bands of C2 and is tentatively identified as emission from excited C4 radicals.

Experimentally determined potentials for the $X ^{2}\ensuremath{\Sigma}^{+}$ and $A ^{2}\ensuremath{\Pi}$ states of the NaNe van der Waals molecule are presented. The potentials are generated from the temperature dependence, in the range 140-330 K, of the intensity in the far-red wing of the Na resonance line perturbed by Ne gas. The NaNe emission spectrum is observed in the wavelength range 585-650 nm. From Morse potential fits to the $A ^{2}\ensuremath{\Pi}$-state data we obtained ${D}_{e}=160(20)$ ${\mathrm{cm}}^{\ensuremath{-}1}$ at ${R}_{e}=5.1(1){a}_{0}$. The $X^{2}\ensuremath{\Sigma}^{+}$ ground state is purely repulsive within the $4\ensuremath{-}7{a}_{0}$ range of our experiment.

The first measurements of the fluorescence spectra of In atoms trapped in Kr and Xe matrices are reported. The In atoms were trapped at 4 °K and the fluorescence was excited by a pulsed dye laser tuned to the matrix-isolated In absorption bands. The results are compared with the previously reported emission spectra of matrix-isolated Tl atoms.

The optical absorption and emission spectra of Na atoms trapped in a Ne matrix at 3°K are reported. From these spectra, the Na-Ne interaction is deduced (AIP).

Pulsed-dye-laser excitation has been used to investigate the optical absorption and emission spectra of Li atoms trapped in Ar, Kr, and Xe matrices at 10 °K. Attempts to stabilize Li atoms in a Ne matrix at 2 °K were unsuccessful. Results for all three rare gases were qualitatively the same. White light absorption scans showed a single absorption with three peaks centered near the free-atom 2s→2p transition wavelength. The intensity of fluorescence produced by dye-laser excitation within this absorption band was measured as a function of emission wavelength. Excitation of the longest- and shortest-wavelength absorption peaks produced identical emission profiles, but no distinct fluorescence signal was detected when the laser was tuned to the central absorption peaks, indicating that the apparent absorption triplet is actually the superposition of a singlet and a doublet absorption originating from two different trapping sites. No additional absorption bands were detected.

The results of pseudopotential calculations of the interaction of an alkali atom with its rare-gas neighbors in a solid matrix are presented. They can explain an interesting effect which appears to be due to optical pumping between two equilibrium positions in a bistable trapping site.