Spontaneous symmetry breaking of acceptors in "Blue" diamonds

The electronic Raman transition between the lower 1s(p(3/2)) and the higher 1s(p(1/2)) State of a hole bound to a boron acceptor in diamond, examined under the high resolution of a Fabry-Perot interferometer, reveals a double t separated by (0.81 +/- 0.15) cm(-1), indicative of a spontaneous symmetry breaking of the fourfold degenerate ground state. The direct transition be tween the levels into which 1s(p(3/2)) : Gamma(8) resolves, with a Raman sh ift of (0.80 +/- 0.04) cm(-1), provides a remarkable confirmation of the sy mmetry lowering shown to arise from a static Jahn-Teller distortion.