Electronic States of Single Vacancies in Diamond

Abstract

Electronic states shown in the title are investigated by using molecular orbital technique and an interpretation is made of the observations on EPR, optical absorption etc. in irradiated diamond. Values of interatomic integrals, which appear in the expression of cohesive energy of a perfect crystal, are firstly modified in such ways that a calculated value of the cohesive energy agrees with the observed one, while values of intra-atomic integrals are set equal to those estimated from the observed values of spectral terms in a free carbon atom. On the basis of these modifications, values of the integrals are then obtained, which are related to electronic states of the vacancies. Energy levels are thus evaluated for V 0 , V + , V - etc., which mean each a neutral, a positively ionized and a negatively ionized vacancy etc.. By comparing these energy levels with each other, it may be assumed that after irradiation with particles of high energy, a much greater of V - appear in the natural crystal than any othe...