表面吸附雙原子分子在外加電場下轉動能態的研究

Abstract

本論文主要研究表面吸附分子在外加電場下的轉動能態，利用矩陣求解方法，求得出垂直和水平吸附分子的轉動能量，結果顯示當外加電場很強時，吸附分子的轉動能量會有很大偏移；當電場強度相對小於禁制位能時，Stark效應受到位能阱抑制，表現不很明顯。 我們也發現到能階有轉折，而且相鄰能階的凹凸處相接近，把禁制位能轉化為一維週期性位能阱，成功地定性解釋能量隨電場強度變化的情形，尤其對轉折，以能階不交錯的特性合理解釋這個現象，配合波函數的角分佈瞭解到：在轉折處相鄰能階為何如此接近。另外由Hellmann-Feynman定理分析，可明確地知道對同一能階而言有多少個轉折，使得我們對外加電場下表面吸附分子的轉動能態有完整的瞭解。

This thesis is devoted to the studies on the rotational states of adsorbed diatomic molecules under the external electric fields. By using the matrix method, the rotational state energies of the hindered rotor were obtained. Our results show that the rotational states of adsorbed diatomic molecules have large energy shifts as well as the free dipole molecules in the very large external electric field. When the field strength is smaller compared with the hindering potential, the Stark effect is suppressed by the conical well and is not prominent. We have also found that the energy levels possess abrupt turning points. The pit and concave places between adjacent levels are very close but do not cross to each other. We convert the hindering potential into the one-dimensional periodic potential and successfully explain the circumstances that the energy levels vary with the electric strengths. For the energy turning points, a simple model is employed to each other to explain this phenomenon. The angular distributions of the wave functions also manifest that adjacent levels are so close at the turning places. Besides, from the Hellmann-Feynman theorem, it is clearly able to point out how many turning places are there for the same level. A complete description about the rotational states of adsorbed diatomic molecules under the external electric fields is presented in the thesis.