High-resolution stimulated Raman study of the first vibrational hot band of 14N2. Separate observation of the spectra of the ortho and para species.


Correspondence to: R. Z Martínez, Instituto de Estructura de la Materia, IEM-CSIC. Serrano 123. 28006 Madrid, Spain.

E-mail: raul@iem.cfmac.csic.es


We present high-resolution stimulated Raman spectra of the first hot band of nitrogen, 14N2, obtained under conditions of low sample pressure and temperature. The use of a Raman optical pumping system allowed us to transfer a significant amount of population to the v = 1 vibrational state, which made possible the observation of the aforementioned hot band with good S/N ratio without resorting to the use of high temperatures or pressures. This has resulted in a more precise and accurate determination of the peak positions than previously existing ones, which in turn has yielded improved values for the molecular constants obtained from the analysis. The rotational selectivity of the pumping process (only one rotational state is initially populated in v = 1), coupled with the negligible probability of nuclear spin interconversion in the time frame of the experiment, has allowed us to observe the hot band spectra of the ortho and para species of 14N2 separately. Copyright © 2013 John Wiley & Sons, Ltd.