One-photon femtosecond laser excitation of photoluminescence from H3 and H4 centers in natural diamond: a method to determine their concentration

The photoluminescence spectra of the dominant H3 and H4 centers in a natural diamond sample, which is preliminarily characterized by optical and infrared spectrophotometry, are excited by femtosecond laser pulses with a wavelength of 470 nm and varying intensity. Saturation of the photoluminescence intensity of the H3 and H4 centers normalized by the intensity of laser radiation is observed and attributed to the saturation of the resonance transition responsible for the excitation. This makes it possible for the first time to estimate the absorption cross sections of H3 and H4 centers, which can be compared with values known from the literature and those determined from photoluminescence kinetics. The total concentration of H3 and H4 centers can then be found. Taking into account the known absorption coefficient of the sample at a wavelength of 470 nm and the previously established ratio of the contributions from H3 and H4 centers, their concentrations have been estimated separately for the first time.