Analysis of sectorial synthetic HPHT diamond plates by laser-induced breakdown spectroscopy considering similarity of ablation processes

Subject of study. This study investigated sectorial synthetic high-pressure high-temperature (HPHT) diamond plates doped with nitrogen or boron. Aim of study. The aim was to analyze the impurity chemical composition of HPHT diamonds across different growth sectors, considering the similarity of ablation processes. Method. Laser-induced breakdown spectroscopy (LIBS) was applied under conditions of laser-induced surface graphitization. Main results. Laser-induced graphitization of the plate surface using a series of laser pulses was characterized by pulse-to-pulse variations in the intensity of the molecular C 2 band in the laser plasma emission spectrum. The similarity of the dependences of the C 2 band intensity change from pulse to pulse was observed. For nitrogen-doped diamonds, a similar trend was also noted for the CN band. Analogous similarities were identified in the emission bands corresponding to hydrogen and oxygen impurities. The intensity of the graphitization process was highest in the (111) growth sector and lowest in the (100) sector, primarily due to significant differences in nitrogen concentration between these sectors. Practical significance. The presence of similarities in the intensity dependences of atomic and molecular emission bands of the relevant chemical elements—and the consistency in the shape of these dependences during irradiation with a series of laser pulses—demonstrate that LIBS can serve as a highly sensitive and effective spectral method for analyzing elemental impurities while identifying the sectorial structure of diamond samples. LIBS can also be employed as a tool for the monitoring and selection of diamond samples.