Electronic Raman and infrared spectra of isotopically controlled ''blue'' diamonds

We report the first observation of the electronic Raman effect in semiconducting p-type, isotopically controlled diamonds. The Raman transition between the spin-orbit split Is ground states of boron accepters occurs at Delta' = 2.07(1) and 2.01(1) meV in natural and C-13 diamonds, respectively. Polarization features show the transition to be predominantly Gamma(5) in character, placing an upper limit on the ratio of the nonspherical Luttinger parameters of the valence band. Host-isotope-related self-energy shifts are observed in both the electronic infrared and Raman spectra.