We report the identification of the vacancy-hydrogen complex in single crystal diamond synthesized by chemical vapor deposition. The $S=1$ defect is observed by electron paramagnetic resonance in the negative charge state. The hydrogen atom is bonded to one of the carbon atoms neighboring the vacancy. Unlike the analogous defect in silicon, no symmetry lowering reconstruction occurs between the three remaining carbon dangling orbitals. The very small measured hydrogen hyperfine interaction is explained by dipolar coupling between the hydrogen and the unpaired electron probability density delocalized on the three equivalent carbon neighbors.

• Received 10 September 2003

DOI:https://doi.org/10.1103/PhysRevLett.92.135502