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 1×1013 cm−2 and annealed at 1400 C. The Xe center exhibits an isolated zero phonon line (ZPL) at 811.7 nm (1.527 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 ΔE=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.