We use single-spin resonant spectroscopy to study the spin structure in the orbital excited-state of a diamond nitrogen-vacancy center at room temperature. We find that the excited state spin levels have a zero-field splitting that is approximately half of the value of the ground state levels, a g-factor similar to the ground state value, and a hyperfine splitting ~20x larger than in the ground state. In addition, the width of the resonances reflects the electronic lifetime in the excited state. We also show that the spin-splitting can significantly differ between NV centers, likely due to the effects of local strain, which provides a pathway to control over the spin Hamiltonian and may be useful for quantum information processing.
@article{arxiv.0806.1939,
title = {Excited-state spectroscopy using single-spin manipulation in diamond},
author = {G. D. Fuchs and V. V. Dobrovitski and R. Hanson and A. Batra and C. D. Weis and T. Schenkel and D. D. Awschalom},
journal= {arXiv preprint arXiv:0806.1939},
year = {2009}
}