THE H2 OPTICAL-TRANSITION IN DIAMOND - THE EFFECTS OF UNIAXIAL-STRESS PERTURBATIONS, TEMPERATURE AND ISOTOPIC-SUBSTITUTION

Uniaxial stress pertubations establish the 1.257 eV 'H2' zero-phonon line as an electric-dipole allowed transition at the centre of a C(2)v point group. Taken in conjunction with a simple one-electron model, the magnitudes of the perturbations support recent suggestions that the H2 centre is a negative charge state of the well-known nitorgen-vacancy-nitrogen 'H3' centre. The H2 zero-phonon line is 0.9 meV higher in energy in C-13 diamond than in C-12 diamond. The shift is consistent, within large uncertainties, with the shift expected from the temperature dependence of the line. A local vibrational mode involving predominantly carbon atoms is identified.