On the existence of a paramagnetic adduct of Ni(II)-bis-(di-n-butyl-diselenocarbamate). An EPR study

Paramagnetic adduct formation of pyridine with nickel(II)-bis(di-n-butyl-diselenocarbamate) is observed by means of EPR at 27°K. The low value of the zero field splitting and the g-factor are explained by strong spin-orbit interactions and by high covalency typical of the Se₄-coordination sphere.     

Spline calculations of the photoionization oscillator strengths of H 3 +

Summary We apply spline methods to the problem of calculating continuum excitation probabilities of molecular systems under the influence of electromagnetic fields. Numerical results are given for the H ₃ ⁺ molecular ion.     

A simple model for the scattering of electrons by a rotating dipole

The coupled equations describing the interaction of one electron with a dipole and hard sphere are shown to be exactly soluble, even when the energy levels of the dipole are taken into account. This model is used to discuss the critical moment for binding the electron in the dipole field. The condition for the existence of Feshbach resonances is similarly discussed. When the model is applied to calculate scattering phase shifts, shape resonances are found.     

Relaxation phenomena associated with microwave pumping of rotational transitions

It is shown that the Bloch equations describing a two-level system in a radiation field can be extended to take proper account of the degenerate magnetic sublevels. By solving the equation for a J = 0 to J = 1 transition in a linear rotor we show that the saturated linewidth depends on the realignment time T₄ as well as on the usual T₁ and T₂. Further we show that the ratio T₁^*/T₂ which enters the saturated linewidth is not exactly unity, and that its deviation from unity is related to the rate of collisional transitions between the two pumped levels. Thus it may be possible to measure collision rates of astrophysical interest which could not be obtained in any other way. Some approximate formulae are derived assuming that only long-range interactions are present.     

Model potential calculations of potential energies of excited states of Li+2

Detailed calculations of the interaction potentials of several electronic states of the Li⁺₂ molecule have been carried out in which the molecule is described as a single electron moving in the field of two polarizable cores. Comparison with the ab initio many-electron calculations of Michels suggests that high accuracy has been achieved at intermediate and large separations. An analysis of the long range behaviour is presented.     

Avoided crossings among the excited states of Na He

A potential maximum in the σ3p state of Na He is explained as an avoided crossing with the σ4s state. All the potentials of states which separate to the almost degenerate 4s, 3d and 4p levels of Na have been calculated, revealing several further interesting pseudocrossings. The possibility of rotational decoupling of the molecular axis during collisions is considered but found not to be important.