Illustration of REMPI. Absorption of photons raises the molecule to an excited state followed by the absorption of photon for ionization.
Schematic representation of the 193 nm laser induced plasma experimental system including a two-wavelength interferometer, spectrometer, and shadowgraphy optical diagnostic equipment. BS––beamsplitter, M––mirror, and W––window.
Sample interferogram with plasma in the measurement arm (left) and the resultant phase distribution in radians calculated using IDEA fringe analysis software (right).
Shadowgrams of the subthreshold intensity, 193 nm, laser induced plasma and associated shockwave.
193 nm laser induced plasma image captured with 75 mm focal length lens.
Plasma line averaged electron density in dry air at 760 Torr with a laser pulse energy of 260 mJ corresponding to a focused irradiance of .
Log-log plot of the peak intensity of the first negative bandhead at 391.4 nm as function of laser energy in dry air at 20 Torr. Slope indicates REMPI of .
Pressure scaling of the first negative bandhead at 391.4 nm from 20 to 800 Torr in dry air with 260 mJ laser pulses.
Broadband emission spectra in dry air at 760 Torr identified as the first negative band system. The dominant peaks belong to the , , and vibrational bandheads.
Comparison of the measured high resolution emission spectrum from the first negative system with SPECAIR generated plot for dry air at 760 Torr.
Velocity of the laser induced plasma shockwave in air with STP just ahead of the front.
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