A Quantitative Analytic Theory of the Spectra of Diatomic Molecules

Abstract

To treat the spectral properties of free diatomic molecules within any particular electronic state, we have developed a quantitative analytic theory to enable the reduction of radial functions that are independent of nuclear mass. From the frequencies of spectral lines for transitions of any type involving a change of rotational angular momentum, the measured data can lead to radial functions for potential energy and for adiabatic and nonadiabatic effects of either nucleus. For electronic states with net electronic spin or orbital angular momentum, the interactions between the various angular momenta produce further radial functions; so far 2Σ, 1Π, 3Σ and 2Π states have been treated in specific applications of the theory. Likewise for intrinsic nuclear angular momenta, several interactions have been treated so as to determine the corresponding radial functions. From either the effects of applied electric and magnetic fields or the intensities of spectral lines due to vibration-rotational transitions, the radial functions for the electric dipole moment, magnetic dipole moment, and electric quadrupole moment have been determined for absorption and emission spectra, and prospectively the electric (dipole) polarizability and (nonlinear) susceptibilities from scattering spectra.