The electronic emission spectrum of triatomic hydrogen. III

The experimental techniques for obtaining spectra of triatomic hydrogen are described with special reference to studies in the infrared. An electronic transition near 3600cm-1 is observed in both H3 and D3. Its analysis shows that it is a 2A1'-2E' transition and that the upper state is identical with the upper state 3s2A1' of the 6025 A band previously analysed (I. Dabrowski and G. Herzberg. Can. J. Phys. 58, 1238 (1980)) while the lower state is the upper state 3p2E' of the 7100 A band (G. Herzberg and J.K.G. Watson. Can. J. Phys. 58, 1250 (1980)). Improved constants are obtained for both these states from the infrared bands of H3 and D3. Perturbations in the upper state 3s2A1' of D3 are clarified. (auth)