The Microwave Absorption Spectrum of Nitrosyl Chloride NOCl

Abstract

The absorption spectrum of nitrosyl chloride has been studied in the region between 21,000 and 23,000 mc/sec. Eight groups of closely spaced absorption lines have been observed; thirty-one individual lines have been resolved. The main features of the observed spectrum can be satisfactorily explained in terms of the rotational transition J = 1\ensuremath{\rightarrow}2 for molecules in the ground and lowest excited vibrational state; the observed hyperfine-structure is satisfactorily explained in terms of nuclear quadrupole interactions involving the chlorine nuclei. The rotational constants for molecules in the ground vibrational state are: for NO${\mathrm{Cl}}^{35}$, $A=2.845$, $B=0.19141$, and $C=0.17934$ ${\mathrm{cm}}^{\ensuremath{-}1}$; for NO${\mathrm{Cl}}^{37}$, $A=2.854$, $B=0.18682$, and $C=0.17534$ ${\mathrm{cm}}^{\ensuremath{-}1}$. Values for the quadrupole interaction terms are given. The ratio $\frac{{Q}^{35}}{{Q}^{37}}$ obtained in this study was 1.34\ifmmode\pm\else\textpm\fi{}0.08.