Abstract
A 248-nm excimer laser was used to produce ionized nitrogen by the process of multiphoton excitation in gaseous nitrogen at room temperature. First-negative emission spectra were analyzed to yield rotational temperatures of typically 600 to 1200 K. Rotational Raman scattering of H2 in gaseous mixtures of N2 and H2 was used to determine if laser heating of the gas produced the observed increase in temperature, but the room temperature value of 295 K was inferred from the H2 Raman data. Therefore the use of spectra produced by multiphoton excitation at 248 nm does not appear to be acceptable for air-temperature diagnostics. emission spectra were also recorded subsequent to optical breakdown in air induced by Nd:YAG 1064-nm radiation, and temperatures were determined to be greater than 5000 K in the decaying plasma.
© 1995 Optical Society of America
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