کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
5375574 | 1504302 | 2009 | 16 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Global analysis of the high resolution infrared spectrum of methane 12CH4 in the region from 0 to 4800Â cmâ1
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کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
شیمی
شیمی تئوریک و عملی
پیش نمایش صفحه اول مقاله
چکیده انگلیسی
We report the global analysis of methane (12CH4) lines from high resolution rovibrational spectra including accurate line positions and intensities in the region 0-4800Â cmâ1. This covers four polyads: The Ground State Monad (rotational levels), the Dyad (940-1850Â cmâ1, 2 vibrational levels, 2 sublevels), the Pentad (2150-3350Â cmâ1, 5 vibrational levels, 9 sublevels) and the Octad (3550-4800Â cmâ1, 8 vibrational levels, 24 sublevels) and some of the associated hot bands (Pentad-Dyad and Octad-Dyad). New Fourier transform infrared (FTIR) spectra of the Pentad and Octad regions have been recorded with a very high resolution (better than 0.001Â cmâ1 instrumental bandwidth, unapodized) at 78Â K using the Bruker IFS 125 HR Zürich prototype (ZP2001) spectrometer in combination with a long optical path collisional cooling system [S. Albert, S. Bauerecker, M. Quack, A. Steinlin, Mol. Phys. 105 (2007) 541]. Existing spectra previously recorded with the FTIR spectrometer at the National Solar Observatory on Kitt Peak in Arizona were remeasured selectively to provide new intensities and positions of weaker lines above 4400Â cmâ1. These were combined with previously reported absorption data from FTIR and laser absorption, as well as high-resolution stimulated Raman and microwave spectra. The effective hamiltonian was expanded up to order 6 for the Ground State, order 6 for the Dyad, order 5 for the Pentad and order 5 for the Octad. A total of 16,738 line positions were used in the least squares adjustment characterized by the following global root mean square deviations dRMS for line positions: 1.3Â ÃÂ 10â4Â cmâ1 for the Dyad, 6.0Â ÃÂ 10â4Â cmâ1 for the Pentad, and 3.5Â ÃÂ 10â3Â cmâ1 for the Octad. Absolute intensities were also analyzed for all the cold bands and some of the hot bands in the region under consideration and we obtained dRMSÂ =Â 9.6% including 3262 experimental line intensities for the Octad. This analysis represents a large improvement over the previous one [J.-C. Hilico, O. Robert, M. Loëte, S. Toumi, A.S. Pine, L.R. Brown, J. Mol. Spectrosc. 208 (2001) 1] with dRMSÂ =Â 0.041Â cmâ1 for positions and 15.6% for intensities in the Octad for a smaller data set. The new results are discussed as benchmarks in relation to accurate potential energy hypersurfaces and for atmospheric and planetary spectra.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Chemical Physics - Volume 356, Issues 1â3, 17 February 2009, Pages 131-146
Journal: Chemical Physics - Volume 356, Issues 1â3, 17 February 2009, Pages 131-146
نویسندگان
S. Albert, S. Bauerecker, V. Boudon, L.R. Brown, J.-P. Champion, M. Loëte, A. Nikitin, M. Quack,