Photolysis of crystalline alkali nitrates via excitation of NO₃ ^- to the state of symmetry 2¹E₁ ^|

Photolysis of crystalline alkali nitrates has been studied using optical, IR, and EPR spectroscopy and chemical analysis of the aqueous solutions of the exposed samples. Excitation of the nitrate ion to 2¹E₁ ^| (a₁ ^| ← e^|) state by exposure to light with wavelength of 172 nm at 300 K leads to formation of nitrite and peroxynitrite ions. The photolysis at 77 K results in formation of fragment NO₂, O^-, and O₃ ^- radicals. The quantum yields of the nitrite and peroxynitrite ions were calculated. The nitrite ions and peroxynitrite ions are formed in deep layers of the samples. The mechanism of radical formation is connected with photochemical transformations of the nitrate ion in the surface layer of the crystal.