Laser-induced luminescence of xenon implanted natural diamond

We report here on laser-induced luminescence studies of the Xe ion related optical center in diamond. The sample with the Xe center was a natural diamond (type Ia) irradiated with 500 keV Xe ions at room temperature with the dose 1 x 10(13) cm(-2) and annealed at 1400 C. The Xe center exhibits an isolated zero phonon line (ZPL) at 811.7 nm (1.521 eV) and a weak vibrational sideband. Growth of a second ZPL at 793.1 nm was observed at elevated temperatures T > 65 K. Using Ti:sapphire laser excitation, it was established that both ZPLs observed are resonance 0-0 lines. It was concluded that the excited state of the optical transition has a double-level structure, and the ground state consists of a single level. The excited state energy level splitting of about DeltaE = 236 +/- 20 cm(-1) was found by studying the temperature behavior of these ZPLs. This splitting is different from the spectroscopic splitting of 289 cm(-1). Possible reasons of the discrepancy are discussed. The vibronic sideband of the ZPL at 811.7 nm with several phonons and quasilocal peaks was observed. The Huang-Rhys factor was determined to be exp(-S) = 0.9 +/- 0.05 at temperature 8 K. (C) 2004 Published by Elsevier B.V.