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.