PIEZO-OPTICAL STUDY OF GRAPHITE IN 3 TO 6 EV RANGE

Piezoreflectivity of graphite has been measured between 3 and 6 eV. The piezospectrum is interpreted as arising from three transitions relevant to the optical spectrum, M1 transition at 3.8 eV, degenerate M1, M2 transitions at 4.5 eV, and M2 transition at 5.2 eV. These energies yield γ1−γ3=0.35 eV and γ0=2.26 eV as the band parameters along the M–L line in the Brillouin zone. The strain coefficients of the parameters are obtained as, Δγ0⁄γ0≅53 per unit strain in the basal plane and Δγ1⁄γ1≅Δγ3⁄γ3≅37 per unit strain along the c-axis. © 1979, THE PHYSICAL SOCIETY OF JAPAN. All rights reserved.