Spontaneous Symmetry Breaking of Acceptors in ''Blue'' Diamonds

The electronic Raman transition between the lower 1s(p3/2) and the higher 1s(p1/2) state of a hole bound to a boron acceptor in diamond, examined under the high resolution of a Fabry-Perot interferometer, reveals a doublet separated by (0.81±0.15) cm-1 , indicative of a spontaneous symmetry breaking of the fourfold degenerate ground state. The direct transition between the levels into which 1s(p3/2) :Γ8 resolves, with a Raman shift of (0.80±0.04) cm-1 , provides a remarkable confirmation of the symmetry lowering shown to arise from a static Jahn-Teller distortion. (c) 1999 The American Physical Society