New High-Resolution Analysis of the nu(3) Band of the (15)N(16)O(2) Isotopomer of Nitrogen Dioxide by Fourier Transform Spectroscopy

New high-resolution Fourier transform absorption spectra of an (15)N(16)O(2) isotopic sample of nitrogen dioxide were recorded at the University of Bremen in the 6.3-µm region. Starting from the results of a previous study [Y. Hamada, J. Mol. Struct. 242, 367-377 (1991)], a new and more extended analysis of the nu(3) band located at 1582.1039 cm(-1) has been performed. The spin-rotation energy levels were satisfactorily reproduced using a theoretical model which takes into account both the Coriolis interactions between the spin-rotation energy levels of the (001) vibrational state with those of the (020) and (100) states and the spin-rotation resonances within each of the NO(2) vibrational states. Precise vibrational energies and rotational, spin-rotation, and coupling constants were obtained in this way for the first triad of (15)N(16)O(2) interacting states {(020), (100), (001)}. Finally, a comprehensive list of line positions and line intensities of the {nu(1), 2nu(2), nu(3)} interacting bands of (15)N(16)O(2) was generated, using for the line intensities the transition moment operators which were obtained previously for the main isotopic species. Copyright 2000 Academic Press.

New High-Resolution Analysis of the 3nu(3) and 2nu(1) + nu(3) Bands of Nitrogen Dioxide (NO(2)) by Fourier Transform Spectroscopy

Using new high-resolution Fourier transform spectra recorded at the University of Denver in the 2-µm region, a new and more extended analysis of the 2nu(1) + nu(3) and 3nu(3) bands of nitrogen dioxide, located at 4179.9374 and 4754.2039 cm(-1), respectively, has been performed. The spin-rotation energy levels were satisfactorily reproduced using a theoretical model that takes into account both the Coriolis interactions between the spin-rotation energy levels of the (201) vibrational "bright" state with those of the (220) "dark" state. The interactions between the (003) bright state with the (022) dark state were similarly treated. The spin-rotation resonances within each of the NO(2) vibrational states were also taken into account. The precise vibrational energies and the rotational, spin-rotational, and coupling constants were obtained for the two dyads {(220), (201)} and {(022), (003)} of the (14)N(16)O(2) interacting states. From the experimental line intensities of the 2nu(1) + nu(3) and 3nu(3) bands, a determination of their vibrational transition moment constants was performed. A comprehensive list of line positions and line intensities of the {2nu(1) + 2nu(2), 2nu(1) + nu(3)} and the {2nu(2) + 2nu(3), 3nu(3)} interacting bands of (14)N(16)O(2) was generated. In addition, assuming the harmonic approximation and using the Hamiltonian constants derived in this work and in previous studies (A. Perrin, J.-M. Flaud, A. Goldman, C. Camy-Peyret, W. J. Lafferty, Ph. Arcas, and C. P. Rinsland, J. Quant. Spectrosc. Radiat. Transfer 60, 839-850 (1998)), we have generated synthetic spectra for the {(022), (003)}-{(040), (021), (002)} hot bands at 6.3 µm and for the {(220), (201)}-{(100), (020), (001)} hot bands at 3.5 µm, which are in good agreement with the observed spectra. Copyright 2000 Academic Press.

Determination of the Line-Shift and Line-Broadening Coefficients in the nu(3) Band of ()NO(2) Perturbed by ()O(2), N(2), H(2), D(2), and CO(2)

A high-resolution three-channel diode-laser spectrometer was used to record a large number of spectra with (14)N(16)O(2) and foreign gas pressures ranging from 0.1 to 0.4 and 20 to 150 Torr, respectively, at room temperature. The 6.2-µm region corresponding to the nu(3) band of NO(2) was analyzed and the broadening and shift coefficients were derived in the case of collisions between NO(2) and H(2), D(2), O(2), N(2), CO(2), and SO(2) for 13 lines with 18 </= N" </= 38 and 1 </= K"(a) </= 5. This experimental study confirms general trends. The broadening coefficients decrease with an increase of the rotational quantum number N" whereas the absolute values of the line-shift coefficient increase with increasing N". In the case of the studied diatomic perturbers the size of the broadening coefficients corresponds to the size of the quadrupole moments. The only collision partner with nonvanishing dipole moment, SO(2), shows the largest broadening effect as expected. All shift coefficients are negative for the lines under study. Copyright 1999 Academic Press.

Analysis of the nu8 + nu9 Band of HNO3, Line Positions and Intensities, and Resonances Involving the v6 = v7 = 1 Dark State

Using a high-resolution (R = 0.0025 cm-1) Fourier transform spectrum of nitric acid recorded at room temperature in the 1100-1240 cm-1 region, it has been possible to perform a more extended analysis of the nu8 + nu9 band of HNO3 centered at 1205.7075 cm-1. As in a recent analysis of this band [W. F. Wang, P. P. Ong, T. L. Tan, E. C. Looi, and H. H. Teo, J. Mol. Spectrosc. 183, 407-413 (1997)], the Hamiltonian used for the line positions calculation takes into account, for the upper state, the DeltaK = +/-2 anharmonic resonance linking the rotational levels of the v8 = v9 = 1 "bright" vibrational state and those of the "dark" v6 = v7 = 1 vibrational state. More than 4800 lines were assigned in the nu8 + nu9 band, which involve significantly higher rotational quantum numbers than in previous works. On the other hand, and surprisingly as compared to previous studies, the nu8 + nu9 band appears to be a hybrid band. In fact, nonnegligible B-type transitions could be clearly identified among the much stronger A-type lines. Accordingly, a set of individual line intensities were measured for lines of both types and were introduced in a least-squares fit to get the A- and B-type components of the transition moment operator. Finally, a synthetic spectrum of the 8.3-µm region of HNO3 has been generated, using for the line positions and line intensities the Hamiltonian constants and the expansion of the transition moment operator which were determined in this work. In this way, the B-type and the A-type components of the nu8 + nu9 band appear to contribute for about (1/4) and (3/4), respectively, to the total band intensity. Copyright 1999 Academic Press.

The High-Resolution Infrared Spectrum of the nu1/2nu2 Fermi Dyad Bands of COF2

High-resolution FTIR data of carbonyl fluoride in the region of the C-O stretch nu1 fundamental have been analyzed. Satisfactory interpretation of the spectral data required a rigorous analysis that involved the inclusion of Fermi resonance with the 2nu2 state and Coriolis interaction with the 2nu3 + nu6 dark state. Deperturbed molecular constants for the three interacting states as well as perturbation parameters that fit the data within the limits of the experimental accuracy of approximately 0.00035 cm-1 have been obtained. Interesting evidence of "axis interchange" in the 2nu2 state has been observed. Copyright 1997 Academic Press. Copyright 1997Academic Press

Improved line parameters for ozone bands in the 10-microm spectral region

A complete update of spectroscopic line parameters for the 10-microm bands of ozone is reported. The listing contains calculated positions, intensities, lower state energies, and air- and self-broadened halfwidths of more than 53,000 lines. The results have been generated using improved spectroscopic parameters obtained in a number of recent high resolution laboratory studies. A total of eighteen bands of (16)O(3) (sixteen hot bands plus the nu(1) and nu(3) fundamentals) are included along with the nu(1) and nu(3) fundamentals of both (16)O(16)O(18)O and (16)O(18)O(16)O. As shown by comparisons of line-by-line simulations with 0.003-cm(-1) resolution balloon-borne stratospheric solar spectra, the new parameters greatly improve the accuracy of atmospheric calculations in the 10-microm region, especially for the isotopic (16)O(16)O(18)O and (16)O(18)O(16)O lines.

Spectroscopic line parameters for the nu(6) band of carbonyl fluoride

New measurements and analysis of high resolution(0.0025 cm(-1)) laboratory spectra of the carbonyl fluoride v6 band are described. The data are used to generate line parameters suitable for high resolution atmospheric studies.