The high-resolution infrared spectrum of 1,2,4-triazine vapor between 550 and 1700 cm(-1)

The Fourier transform gas-phase IR spectrum of 1,2,4-triazine between 550 a nd 1700 cm(-1) was measured with a resolution of ca. 0.003 cm(-1). Comparin g with the liquid-phase IR and Raman spectra and using ab initio prediction s, most of the fundamental bands of 1,2,4-triazine below 1600 cm(-1) were a ssigned. From the high-resolution gas-phase spectra, 12 of the fundamental bands were analyzed by the Watson Hamiltonian model to yield upper state sp ectroscopic constants. A number of local resonances were identified and exp lained. From a simultaneous ground state combination difference analysis of four of the bands, a set of ground state rotational and centrifugal distor tion constants were obtained. (C) 1999 Academic Press.