17 research outputs found
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Plasma channel optical-pumping device and method
A device and method are described for optically pumping a gaseous laser using blackbody radiation produced by a plasma channel which is formed from an electrical discharge between two electrodes spaced at opposite longitudinal ends of the laser. A preionization device which can comprise a laser or electron beam accelerator produces a preionization beam which is sufficient to cause an elctrical discharge between the electrodes to initiate the plasma channel along the preionization path. The optical pumping energy is supplied by a high voltage power supply rather than by the preionization beam. High output optical intensities are produced by the laser due to the high temperature black-body radiation produced by the plasma channel, in the same manner as an exploding wire type laser. However, unlike the exploding wire type laser, the disclosed invention can be operated in a repetitive manner by utilizing a repetitive pulsed preionization device
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Characterization of multiple-photon absorption and dissociation of polyatomic molecules
A quantitative comparison of multiple-photon absorption (MPA) and dissociation (MPD) has been performed for experiments with a number of different polyatomic molecules. Appropriate normalization techniques for the absorption and dissociation parameters are formulated to account for the different conditions of the experiment and the molecular parameters. This procedure in a first approximation, accounts for the effects of independent variables such as gas pressure, optical bandwidth, optical pulse duration, excitation frequency, spectral width of the optical absorption band, absorption strength of the transition, bond strength, and the density of states in the molecule. The theoretical description of the dynamics of the absorbing ground state is considered and used to provide the rationale for the normalization procedure. The results of this analysis indicate that the functional dependence of the number of photons absorbed per molecule with fluence is qualitatively the same for the most molecules. Similarly, the probability for dissociation of most molecules can be related to the density of vibrational states, the bond strength, the number of photons absorbed per molecule, and the width of the absorbing transition. The functional relationships derived for MPA and MPD can be related to several theoretical aspects of the optical interaction process. In particular, the implications for the basic absorption mechanisms and the distribution of vibrational energy in the molecule will be addressed
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Multiple-photon excitation of polyatomic molecules in a strong optical field: a universal normalization
The phenomenon of Multiple Photon Excitation (MPE) of polyatomic molecules by a (laser) optical field has proved to be quite general. We have been attempting for some time to relate the absorption response of a molecule to the optical driving force in terms of a general model which would take into account the important molecular parameters. A picture of the interaction has emerged which emphasizes the dynamics of absorption within a single vibrational manifold with rapid intramodal coupling to other vibrational modes. The similarity between this picture of the excitation process by an optical field and the de-excitation process for vibrational relaxation of polyatomics provided strong motivation to seek a universal curve for the MPE process by analogy to the Lambert--Salter correlation for relaxation processes
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