Stephen C. Wallace, R.T. Hodgson, et al.
Applied Physics Letters
In alkali-halide crystals, dipolar impurities such as CN- and OH- exhibit energy-level spacings of 0.1-2 cm-1 due to a reorientational type of motion. One calculation of these energy-level spacings is on the basis of a hindered-rotor model, which expresses the rotational motion as a linear combination of spherical-harmonic wave functions. This model is applicable when small or medium potential-energy barriers hinder the rotation. The tunneling model calculates these same energy levels by allowing localized harmonic-oscillator wave functions to overlap the equivalent wave functions in neighboring (but differently oriented) potential wells. The latter model was derived by Gomez et al. only for off-center point masses; furthermore, this model is primarily applicable to cases involving medium or large potential barriers. The present work reformulates the tunneling-model results, so that they are applicable to the cases of rotating polyatomic impurities. It then becomes evident that the two models predict quite similar energy-level spacings over a large range of intermediate barrier heights. An interesting prediction is obtained by utilizing both the hindered-rotor and tunneling models to analyze experimental results from the KCI
Stephen C. Wallace, R.T. Hodgson, et al.
Applied Physics Letters
R.B. Laibowitz, R.W. Dreyfus
Journal of Applied Physics
F.Alan McDonald, R.J. von Gutfeld, et al.
IUS 1985
R.W. Dreyfus, A.J. Landon
IEEE Transactions on Magnetics