Indirect energy gap ofC13diamond

Abstract

Optical-absorption and luminescence measurements on ${}_{}{}^{13}{}_{}{}^{}\mathrm{C}$ and ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ diamonds establish that the indirect energy gap is 13.6±0.2 meV higher for ${}_{}{}^{13}{}_{}{}^{}\mathrm{C}$ than for ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ diamond. Zero-parameter calculations, allowing for the changes in electron-phonon coupling and lattice parameter, give an estimated shift of 16.5±2.5 meV.