Hindered rotation and external electric field effect of adsorbed diatomic molecules

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 field 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.