Pressure and Laser-Induced Reactivity in Crystalline s-Triazine

The high-pressure transformation of s-triazine to an extended amorphous carbon incorporating a large amount of nitrogen has been studied by Fourier transform infrared spectroscopy. The reaction, occurring at ambient temperature around 8 GPa, is found to be extremely sensitive to temperature, as the reaction onset is lowered to 4 GPa at 530 K. Also, laser irradiation allows a very selective trigger of the reactivity below the ambient temperature threshold likely due to the population of ππ* states. Independently of temperature and irradiation conditions, two different products are obtained once the reaction is activated at 3.5–4.0 GPa or above 8 GPa. The low pressure product is likely composed by conjugated domains forming in the monoclinic ab planes, whereas with rising pressure interactions between the planes destroy the sp 2 clusters increasing the concentration of N bearing terminating groups and severely affecting the mechanical properties of the extended material.