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Lasing on the B→X bands of CdI at 655 nm and CdBr at 811 nm has been obtained by photodissociating CdI2 and CdBr2 with an ArF laser. Also, the CdX (X = I, Br) B-state radiative lifetimes and CdX2 quenching rate constants were found to be 32±3 ns, (9.2±1.1)×10−10 cm3 s−1, 25±4 ns and (7.9±3.3)×10−10 cm3 s−1, respectively. After synthesizing and photodissociating 114CdI2, the 114CdI laser spectrum was identified as arising from v′ = 0−2→v\ = 61, 62 transitions of the B→X band. The use of a single isotope of Cd (i.e., 114Cd) was also found to quadruple the energy output of the CdI laser and to make possible a dual-wavelength metal-halide laser, one operating simultaneously in the red (CdI) and near-infrared (CdBr).

Electronically excited XeCl molecules are produced directly from xenon and chlorine atoms in mixtures of Xe and Cl2 vapor at room temperature by laser photoassociation at λ=308 nm. The peak intensities of both the XeCl(C→A) and Xe2Cl 4 2Γ→2 2Γ spontaneous emission signals at 350 and ∼485 nm, respectively, are linear in laser fluence and Cl2 partial pressure. Consequently, the XeCl excimer production mechanism is one involving Xe, Cl and one 4 eV photon in which Cl2 is photodissociated on the X 1∑→1Π band throughout the XeCl laser pulse. This conclusion is supported by the enhancements of the XeCl(C) state population of more than 15 that are observed when the Xe/Cl2 mixture is irradiated by an additional ultraviolet (UV) laser pulse [of wavelength 351 nm (XeF), 308 or 193 nm (ArF)] that arrives prior to firing the XeCl laser. The effect is much more pronounced at 193 nm than at the other wavelengths, indicating tht the Cl concentration is augmented by photoionizing Xe, followed by XeCl excimer formation and dissociation of the weakly bound ground state. Also, the radiative lifetime of the Xe2Cl 4 2Γ state was measured to be 245±10 ns.

Erratum: "Epitaxial growth of ZnY ferrite films by pulsed laser deposition" [J. Discharge pumped ZnI (599-606 nm) and CdI (653-662 nm) amplifiers Appl. Phys. Lett. 42, 20 (1983); 10.1063/1.93750 Fluorescence lifetime studies of NO2. I. Excitation of the perturbed 2 B 2 state near 600 nm

Three-photon ionization of xenon, resonantly enhanced by the Xe 6p [1/2]c state at g0 119 cm ', is observed when a xenon atom simultaneously absorbs one ArF (51733-cm ') and two XeF (28482-cm ) photons. For ArF and XeF laser intensities in the 1 -100-MWcm range, the peak electron density is more than an order-of-magnitude larger than that obtainable by the nonresonant, two-photon ionization of Xe by ArF. The spontaneous radiative lifetime of the 6p[1/2]c level and the rate constant for quenching of the state by background Xe atoms were measured to be 29 +4 ns and 4+1 &&10 'c cm3 s ', respectively. Excitation of the 6p [1/2]c state is both selective and intense and has resulted in iasing on the 6p[1/2]c 6s[3/2]t transition at 828.0 nm, which represents the first optically pumped rare-gas laser.While electron beam and discharge excitation are capable of producing large concentrations of atomic ions in the gas phase, neither possesses the state selectivity that is characteristic of laser pumping but instead produces an array of neutral and ionic species. The large ionization potentials of the rare gases, however, have hindered the widespread application of linear optical pumping techniques and so, in recent years, considerable effort has been expended in developing nonlinear, multiphoton excitation and ionization schemes (involving lasers of high peak power) for the rare gases. Nonresonant multiphoton ionization of the rare gases using ruby' or an harmonic of Nd: YAG (Ref. 2) and resonantly enhanced ionization, exploiting the tunability of a dye laser, have been demonstrated.Due to the small cross sections inherent with nonresonant processes, the former approach requires enormous () 109 -10ta W cm ') intensities to obtain (even for the heavier rare gases) modest ion densities while the latter generally sacrifices laser pulse energy.These limitations can be circumvented by utilizing the high peak power and photon energy combinations that are obtainable with the use of two or more raregashalide excimer lasers. With this laser family, two photon-allowed excited states from 7 to -13 eV can be studied and no more than four photons are required to ionize any of the rare gases.Although neutral excited states of Xe and Kr have been produced with excimer laser radiation of a single wavelength, photoionization of only Xe has been reported. The coefficient for two-photon ionization of Xe at 193 nm (ArF) has been calculated' and recently measured ' and three-photon resonant, fourphoton ionization of Xe at 351 nm (XeF) has been observed. 9The observation of three-photon ionization of Xe (where ht t W h t z = h v3), resonantly enhanced by the 6p[1/2]c state at 80119 cm ' (2ps in Paschen nota-tion), is reported in this Communication. The simultaneous absorption of one ArF (51 733 cm ') and two XeF (28482 cm ') photons by the atom is found, for laser intensities in the 1 -100 MWcm ' range, to enhance the Xe+ ion production rate by at least an order of magnitude over the two ArF photon, nonresonant process. While representing a mode...