Laser Spectroscopy in Supersonic Beams

An interesting development in the high-resolution spectroscopy of complex molecules in molecular beams takes advantage of the internal cooling of molecules in supersonic beams [10.13]. When a gas expands freely from a 

Typical values achieved for these temperatures in supersonic beams at oven pressures of some atmospheres are 

This internal cooling has two definite advantages for high-resolution laser spectroscopy. 

Since the intensities of absorption lines are proportional to the population densities n(v,J) of the absorbing levels, this reduction of n(v,J) to a few populated levels implies a considerable reduction of the number of 

Reduction of the complexity of the NO2 excitation spectrum by internal cooling in a supersonic beam, (a) Conventional room temperature sample of pure NO at 0.04 torr, (b) supersonic beam of pure NO , (c) supersonic beam of S% NO in Ar. The excitation source was a cw dye laser with 0.5 A bandwidth [10.13] 

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