Abstract: The photolysis mechanism of N 2-saturated CS₂-HNO₂ aqueous solution was studied by means of the laser-photolysis/transient absorption technique at 355 nm. Spectra analysis shows that the oxidation of CS₂ in HNO₂ aqueous solution occurs via a complex reaction mechanism.One route is the rapid addiction of ·OH to CS₂ to form CS₂OH adduct, which successively reacts with HONO to form CS₂OH-HONO adduct.Five transient absorption peaks(285, 305, 475, 490 and 980 nm) are attributed to CS₂OH-HONO and the rate coefficient for CS₂OH+HONO reaction is (2.79±0.05)×10⁸ L/(mol·s). The other reaction route is addiction of NO⁺ to CS₂ to form CS₂NO⁺ adduct which has an absorption peak of 230 nm. The first order decay rate coefficient for CS₂NO⁺ is 1.28×10⁵ s^-1.

Key words: Laser flash photolysis, Nitrous acid, Transient absorption spectrum