The Beta Bands of Nitric Oxide. II. Intensity Relations and Their Interpretation

Relative intensities of band lines.---The equations of H\"onl and London predicting the relative intensities of band spectrum lines have been tested with the NO β bands (²P→²P transition), a system emitted by an odd molecule, in the same way that they were recently teste d by one of the writers with certain spectra of even molecules. Plates of the β bands used n connection with Part I were measured with a densitometer. The data are compared with theory, first, as to order of intensity of lines, and, second, as to quantitative intensities calculated from densities under reasonable assumptions. (Calibration curves of the relationship between light intensity and photographic density for the plates were unfortunately not available.) Best agreement is obtained if it is assumed that the effective temeperature of the active nitrogen source was about 47^∘{}C. The observed relative line intnsities are then in essential agreement with those predicted by the H\"onl and London equation s. Possible slight departures from exact agreement are discussed. The two sub-bands (²P₁→²P₁ and ²P₂→²P₂) in each band are found to be approximately equal in intensity, in agreement with Hund's theory.Missing lines and Q branches.---The densitometer curves confirm the conclusions of Part I as to the actual absence of lines expected to be missing if the electronic transitions are ²P₁→²P₁ and ²P₂→²P₂. The shape of the quantitative intensity curves as a function of j is given correctly by the equations of H\"onl and London, for low values of j, only if the values σ₁^'=σ₁^''=1/2 for ²P₁ and σ₂^'=σ₂^''=11/2 for ²P₂ are used in the equations. The values of σ are thereby directly determined to within about a quarter unit.Band intensities.---Curves for the potential energy of the NO molecule as a function of nuclear separation have been calculated from the data of Part I. These have been used by Condon's method to predict the relative intensities of the bands of the β system. These are compared with the relative intensities observed recently by R. C. Johnson and H. G. Jenkins. The principal features of the intensity distribution, which is that typical of a molecule whose moment of inertia changes considerably during emission, are as predicted, but certain discrepancies are noted.