We have investigated the rotational relaxation of NH3 in NH3-He supersonic expansions by means of opto-thermal spectroscopy. Molecules are excited in the v3 + v4 band, around 5100 cm -1, using the third Stokes line of a Raman-shifted pulsed laser. Rotational distributions are measured for different values of the source stagnation pressure and NH3 concentration. At low rotational temperatures, populations deviate from a Boltzmann distribution. This is attributed to the reduction of para-to-ortho conversion during the expansion.
An Opto-Thermal Study of NH3 Rotational Relaxation in NH3-He Supersonic Expansions
Zen, Mario;Boschetti, Andrea;
1988-01-01
Abstract
We have investigated the rotational relaxation of NH3 in NH3-He supersonic expansions by means of opto-thermal spectroscopy. Molecules are excited in the v3 + v4 band, around 5100 cm -1, using the third Stokes line of a Raman-shifted pulsed laser. Rotational distributions are measured for different values of the source stagnation pressure and NH3 concentration. At low rotational temperatures, populations deviate from a Boltzmann distribution. This is attributed to the reduction of para-to-ortho conversion during the expansion.File in questo prodotto:
Non ci sono file associati a questo prodotto.
I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
