Assignments and intensities of (NH3)-N-14 hot bands in the 5-to 8-mu m (3 nu(2)-nu(2),nu(2)+nu(4)-nu(2)) and 4-mu m (4 nu(2)-nu(2), nu(1)-nu(2), nu(3)-nu(2) and 2 nu(4)-nu(2)) regions

摘要

To complete the analysis of the complex infrared spectra of (NH3)-N-14 in the 4- to 8-mum region, we assigned nearly 1200 transitions in the 3 upsilon (2) - upsilon (2), upsilon (2) + upsilon (4) - upsilon (2), upsilon (1) - upsilon (2), upsilon (3) - upsilon (2), 2 upsilon (4) - upsilon (2), and 4 upsilon (2) - upsilon (2) hot bands using the upper state energy levels determined by our previous studies at 4 and 3 mum (J. Mol. Spectrosc. 173, 120-145 (1995); 193, 46-71 (1999)). Line intensities of those hot bands were analyzed using measurements retrieved from 0.0056 and 0.011 cm(-1) unapodized resolution FT spectra recorded at Kitt Peak National Observatory. By a least-squares fit of vibrational-inversion transition moments, over 770 intensity measurements are modeled to +/-7.2% and +/-8.9% in the 5- to 8-mum and 4-mum in regions, respectively. The values of the transition dipole moment were determined to obtain the band strengths of hot bands. In the 5- to 8-mum region, the band strengths in cm(-2) atm(-1) at 296 K of 3 upsilon (2) - upsilon (2) (a <-- s), 3 upsilon (2) - upsilon (2) (s <-- a), upsilon (2) + upsilon4 - upsilon (2) (s <-- s) and upsilon (2) + upsilon (4) - upsilon (2) (a <-- a) were found to be 0.000075(23), 0.351(22), 0.689(32), and 0.525(44), respectively. In the 4-mum region, for the upsilon (3) - upsilon (2) (s <-- s), upsilon (3) - upsilon (2), (a <-- a), 2 upsilon (l4=+/-2)(4)-upsilon (2) (s <-- s). and 2 upsilon (l4=+/-2)(4)-upsilon (2) (a <-- a), they were estimated to be 0.0703(32), 0.0599(27), 0.00547(34), and 0.00473(29), respectively at 296 K. Also, about 100 line intensities of the upsilon (1)- upsilon (2) (a <-- s), upsilon (1)- upsilon (2) (s <-- a), 2 upsilon (l4=+/-2)(4)-upsilon (2) (a <-- s), 2 upsilon (l4=0)(4)-upsilon (2) (s <-- a), and 4 upsilon (2) - upsilon (2) (s <-- a) weak hot bands were measured and reported. The prediction generated by the present study is available for the detection of (NH3)-N-14 in exoplanet atmospheres and brown dwarf stars with relatively high temperature (similar to 1000 K), A few self-broadened linewidths are reported to demonstrate that there is a large variation with the vibrational quanta. (C) 2001 Academic Press. [References: 25]