Spectroscopic studies of the Jahn-Teller effect in the Ã2E″ state of the nitrate radical NO3

► We observe hot bands and the forbidden origin of the A˜2E″←X˜2A2′ spectrum. ► We determine the frequencies for 3 of the 4 fundamental vibrations of the à state. ► We measure the E(E″)-E(A1″) vibronic splitting in the ν4′ = 1, E″⊗e′ manifold.