Fourier Transform Emission Spectroscopy of the A' 1Pi-X1Sigma+ and A1Pi-X1Sigma+ Systems of IrN.

The emission spectrum of IrN has been investigated in the 10 000-20 000 cm-1 region at 0.02 cm-1 resolution using a Fourier transform spectrometer. The bands were excited in an Ir hollow cathode lamp operated with a mixture of 2 Torr of Ne and a trace of N2. Numerous bands have been classified into two transitions labeled as A1Pi-X1Sigma+ and A' 1Pi-X1Sigma+ by analogy with the isoelectronic PtC molecule. Ten bands involving vibrational levels up to Kv = 4 in the ground and excited states have been identified in the A1Pi-X1Sigma+ transition. This electronic transition has been previously observed by [A. J. Marr, M. E. Flores, and T. C. Steimle, J. Chem. Phys. 104, 8183-8196 (1996)]. To lower wavenumbers, five additional bands with R heads near 12 021, 12 816, 13 135, 14 136, and 15 125 cm-1 have been assigned as the 0-1, 3-3, 0-0, 1-0, and 2-0 bands, respectively, of the new A' 1Pi-X1Sigma+ transition. A rotational analysis of these bands has been carried out and equilibrium constants for the ground and excited states have been extracted. The Kv = 2 and 3 vibrational levels of the A' 1Pi state interact with the Kv = 0 and 1 levels of the A1Pi state and cause global perturbations in the bands. The ground state equilibrium constants for 193IrN are: omegae = 1126.176360(61) cm-1, omegaexe = 6.289697(32) cm-1, Be = 0.5001033(20) cm-1, alphae = 0.0032006(20) cm-1, and re = 1.6068276(32) Å. Copyright 1999 Academic Press.