Browsing by Author "Mei, WN"

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Higher-order corrections to the excited states using the logarithmic perturbation method
(1998-07-01)
Mei, WN
;
Chuu, DS
;
電子物理學系
;
Department of Electrophysics
Based on the logarithmic perturbation method proposed by Aharonov and Au [Phys. Rev. Lett. 42, 1582 (1979)], we calculate explicitly up to fourth order and arrive at different results for the energy corrections and nodal point shifts of the first excited state.
Hindered and modulated rotational states and spectra of adsorbed diatomic molecules
(1996-10-15)
Shih, YT
;
Chuu, DS
;
Mei, WN
;
電子物理學系
;
光電工程研究所
Both vertical and horizontal adsorption configurations of a diatomic molecule were modeled as the rigid rotor with which thr spatial motion was confined by a finite conical well. In addition to the polar hindering potential, a sinusoidal azimuthal modulation. which bears the local symmetry of the adsorption site, was incorporated. Eigenfunctions for different models were expressed analytically in terms of the hypergeometric functions, and eigenvalues were solved numerically. We found that the rotational energy levels exhibit oscillatory behavior when plotted as functions of the hindrance angle. This particular phenomenon was interpreted as the occurrence of resonance transmission of the rotor wave function at certain hindrance condition. We also found that the rotational levels were grouped into bands when the azimuthal modulation strength was increased. The solutions were used to calculate the rotational-state distribution of desorbed molecules, and agreement with the previous experiment was obtained.
Hindered rotation and external electric field effect of adsorbed diatomic molecules
(1996-09-01)
Shih, YT
;
Chunu, DS
;
Mei, WN
;
電子物理學系
;
光電工程學系
A finite conical well was proposed to model the surface hindering potential to which a horizontally adsorbed molecule is subjected. Eigenfunctions and eigenvalues for this model were presented. In addition to the hindering rotation, the external electric field effect on the rotational states of a horizontally adsorbed dipole molecule was also investigated by variational calculation. We found that, as with our previous result of the vertical configuration, the rotational energy Levels of the horizontally adsorbed molecule exhibit oscillatory behavior when plotted as functions of the hindrance angle. On the other hand, our result showed that the Stark shifts of the rotational energies were suppressed by the conical well if the field strength is not comparable with the hindering potential. However, when the applied held is strong, large negative shifts were found. Furthermore, the plotted angular distributions of wave function showed that a very strong electric field will enduce a change of adsorption configuration from horizontal to vertical. Copyright (C) 1996 Published by Elsevier Science Ltd