金刚石附氢(100)面脱氢势垒的量子化学研究

采用MNDO（UHF）方法计算了金刚石（100）－（1×1）：2H双氢化表面和（100）－（2×1）：H单氢化表面的脱氢势垒，论证了决定金刚石附氢表面脱氢势垒大小的主要因素是气相－表面吸附氢原子间的相互排斥大小，得出（100）面两种表面结构脱氢势垒的理论预言值分别为71和59kJ·mol-1，均大于（111）面脱氢势垒的理论预言值42kJ·mol-1．揭示了在同等生长条件下金刚石（111）面可供成核和生长的反应基多于（100）面，与实验上得到的同等生长条件下（111）面的相对生长率大于（100）面的结论是一致的。

Quantum Chemical Study of Hydrogen Abstraction from a Diamond (100) Surface

ion of terminal hydrogens on a diamond (100) surface by atomic hydrogen has been considered as a possible rate-determining elementary step in the mechanism of low-pressure diamond growth by chemical vapor deposition. The author used MNDO(UHF) methods to estimate the potential barrier for this abstraction reaction. It is predicted that the theoretical values of the potential barrier for H abstraction from full dihydride (100)-(1×1):2H and monohydride (100)-(2×1):H diamond surface are 71 and 59kJ?mol respectively. The potential barrier for H abstraction from diamond (111) surface is smaller than those of diamond (100) surfaces. This results indicated that the creation of radical sites on diamond (111) surface via H abstraction is easier than that on (100) surface under the same growing condition. This conclution therefore supports the experimental result that the relative growth rate of (111) surface is greater than that of (100) surface.