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We have investigated the laser performance of the 1S0–1D2 and 1S0–3P1 electric‐dipole‐forbidden transitions of the ground configuration of selenium atoms using 172 nm photolysis of OCSe to produce large concentrations of Se(1S). With complete dissociation of OCSe the Se(1S) atoms are quenched by photoelectrons and Se(3P) atoms, both undesired products of the photolysis. The quenching by electrons is removed and the laser performance is greatly improved by employing small concentrations of SF6 for electron attachment. At optimized conditions, we have obtained a laser output on both transitions corresponding to 0.3 photons for each OCSe molecule initially in the laser volume. We have also investigated the effects on the lasers of collision broadening and collision‐induced emission and have demonstrated XeSe and KrSe collision‐induced lasers operating at wavelengths near the Se(1S0–1D2) transition.

The bipolar diffusion charging of particles, suspended in argon is investigated. Particle charge is measured as function of particle size and ion concentration. Since rare gases do not attach electrons, free electrons are available in the gas. This leads to a large difference in mobility and attachment coefficients between negative and positive charge carriers and also of the resulting particle charge. Additionally, negatively charged particles have a maximum as function of the ion concentration, before the equilibrium is reached. This can be explained by the existence of two types of negative charge carriers: free electrons and negative ions, formed by attachment of electrons to impurities in the gas.

Strong laser oscillation has been obtained on the electric‐dipole‐forbidden 1S0‐1D2 transition of atomic sulfur using 146‐nm photodissociation of OCS. A photolytic mixture of OCS with N2 and SF6 produced optimum laser performance. Based on the laser output energy of 5 mJ at 772.5 nm, we infer that an energy density of 2.5 J/liter was stored in the laser transition immediately following photolysis. The one‐half quenching time of S(1S) atoms was approximately 1 μs for these conditions.