Black phosphorus (BP) is a two-dimensional semiconductor of remarkable properties, such as high carrier mobility and a thickness-dependent direct band gap. When exposed to light, BP reacts with oxygen and water, which complicates further investigations in normal conditions. Previous studies have shown that the reaction leads to an oxidation, which accumulates as phosphoric acid on the surface [1]. Here, we discuss recent observations on new degradation by-products containing nitrogen, which have not been yet reported in the literature. The vibrational modes of the degradation compounds were monitored using polarized Raman spectroscopy at different excitation wavelengths and under different conditions, such as isotopic markers of atmospheric gases. By controlling the conditions, the experiments allow us to acquire information on the nature of these by-products and their formation mechanism.

[1] Favron, A., Gaufrès, E., Fossard, F., Phaneuf-L’Heureux, A. L., Tang, N. Y., Lévesque, P. L., ... & Martel, R. Photooxidation and quantum confinement effects in exfoliated black phosphorus. Nature materials, 2015, 14(8), 826-832.