Electron Paramagnetic Resonance Sensing of «Hidden» Atomistic and Cooperative Defects in Femtosecond Laser-Inscribed Photoluminescent Encoding Patterns in Diamond

Abstract

The changes that appeared in the crystal structure of a natural diamond under the influence of a pulsed femtosecond laser (525 nm) were comprehensively investigated using Fourier-transform infrared (FT-IR), electron paramagnetic resonance (EPR), and photoluminescence (PL) spectroscopy methods. It is shown that changes in the crystal structure occur due to the laser-driven interrelated process of the appearance and migration of interstitial carbon atoms and vacancies. On the one hand, there are atomistic transformations related to a decrease in the concentrations of structural centers that are not associated with vacancies or interstitial atoms—centers A (FT-IR spectroscopy) and P1 and W7 (EPR)—and an increase in the concentration of the H3, NV0, and NV− (PL) centers, which are associated with vacancies. On the other hand, there are indications of cooperative effects—an increase in the intensity of multi-atomic B2 (platelets, layers of interstitial carbon atoms (FT-IR)) and N2 (fragments of the structure with broken C–C bonds (EPR)) centers.