New Method for the Measurement of Microwave Integrated Line Intensities and Line Widths

Abstract

A method is described for the measurement of microwave line widths and integrated intensities with Stark‐modulation spectrometers. The method makes use of a property that the peak intensity α_max,meas, measured at a given Stark field E, depends, under certain conditions, only on the half‐width a and the peak intensity α_max. In the present investigation, the method has been used with a Stark cavity spectrometer employing ``antimodulation'' techniques which were described in an earlier paper. Experimental procedure, and the possibilities of the method are illustrated by measurements on two lines arising from the J=1→2 rotational transition of the ¹⁶O¹²C³²S molecule in the ground state, and in the excited bending‐vibrational state (l‐doublet). The measured integrated intensity of the ground‐state line of (103±3.5)10^—5 cm^—1 sec^—1 at 1 mm Hg agrees well with the theoretical value of 101.5·10^—5 cm^—1 sec^—1. The half‐width constant of the ground‐state line and of the l‐doublet line was found to be 6.27±0.18 and 6.17±0.23 Mc/mm Hg, respectively. From the measurements on the various mixtures of OCS and N₂, a value of 4.36±0.12 Mc/mm Hg has been obtained for the collision broadening factor for OCS molecules with N₂ molecules. The present method is applicable to sharp (also weak) lines of which the Stark splitting pattern is quantitatively known.