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 sp2 clusters increasing the concentration of N bearing terminating groups and severely affecting the mechanical properties of the extended material.