Lifetime and quantum efficiency of luminescence due to indirect excitons in a diamond

Photoluminescence due to indirect excitons in a high-pressure synthetic diamond crystal of type IIa has been studied. We measured the time decay of the luminescence and the absolute intensities of incident, reflected and transmitted light of the excitation laser at 83 K. Analyzing these results, the quantum efficiency η of the luminescence and the radiative transition probability τR−1 of the indirect excitons were estimated for the first time. Those values are 2.27×10−2 and 4.3×105 s−1, respectively. It is reasonable that the radiative lifetime of the excitons estimated to be 2.3 μs because of indirect properties of the excitons in a diamond.