X-band electron paramagnetic resonance spectroscopy measurement was performed at room temperature using Bruker EMXplus spectrometer systems equipped with a wide band preamplifier in the microwave bridge. Microwave frequency was 9.614 GHz. The second harmonics (532 nm) of a Nd:YAG laser (Q2-B20, Quantum Light Instruments, fwhm = 5 ns) was used for the light excitation.