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Preliminary Modeling of CH3D From 4000 to 4550 cm (exp-1)
External Online Source: doi:10.1016/j.jqsrt.2012.08.005
Author and Affiliation:
Nikitin, A. V.(International Science and Technology Center, Moscow, Russian Federation);
Brown, L. R.(Jet Propulsion Lab., California Inst. of Tech., Pasadena, CA, United States);
Sung, K.(Jet Propulsion Lab., California Inst. of Tech., Pasadena, CA, United States);
Tyuterev, Vl. G.(Reims Univ., France);
Smith, M. A. H.(NASA Langley Research Center, Hampton, VA, United States);
Mantz, A. W.(Connecticut Coll., New London, CT, United States)
Abstract: A new study of 12CH3D line positions and intensities was performed for the upper portion of the Enneadecad polyad between 4000 and 4550/cm. For this, FTIR spectra were recorded with D-enriched methane samples (at 80 K with a Bruker 125 IFS at 0.005/cm resolution and at 291 K with the McMath-Pierce FTS at 0.011/cm resolution, respectively). Line positions and intensities were retrieved by least square curve-fitting procedures and analyzed using the effective Hamiltonian and the effective dipole moment expressed in terms of irreducible tensor operators adapted to symmetric top molecules. Initially, only the cold spectrum was used to identify quantum assignments and predict 12CH3D relative intensities in this region. To assign higher quanta up to J equal 14, additional line positions and intensities were obtained from two room temperature spectra. In the final stage, measured intensities from both the cold and the room temperature data were normalized to corresponding values at 296 K and then averaged. Combining the two temperature datasets confirmed the assumed quantum assignments and also demonstrated the relative accuracies to be better than 70.0002/cm for line positions and at least +/-6% for intensities so that approx.1160 features were selected. Including additional assignments from the room temperature spectra alone permitted 1362 line intensities of 11 bands (involving 23 vibrational symmetry components) to be reproduced with an RMS of 9%. Over 4085 selected positions for 12 bands were modeled to 0.008/cm. Nevertheless a number of known assignments could not be modeled to within our experimental precisions. More work is needed to obtain a complete characterization of this complex polyad.
Publication Date: Aug 23, 2012
Document ID:
20130003301
(Acquired Jan 27, 2013)
Subject Category: SPACE SCIENCES (GENERAL)
Report/Patent Number: NF1676L-15060
Document Type: Journal Article
Publication Information: Journal of Quantitative Spectroscopy and Radiative Transfer; Volume 114; 1-12
Publisher Information: Elsevier Science Publishers, Amsterdam,, Netherlands
Contract/Grant/Task Num: WBS 281945.02.42.01.98
Financial Sponsor: NASA Langley Research Center; Hampton, VA, United States
Organization Source: NASA Langley Research Center; Hampton, VA, United States
Description: 12p; In English; Original contains color and black and white illustrations
Distribution Limits: Unclassified; Publicly available; Unlimited
Rights: Copyright
NASA Terms: METHANE; TEMPERATURE EFFECTS; DIPOLE MOMENTS; INFRARED SPECTRA; PLANETARY SYSTEMS; TITAN; SPECTRA; SYMMETRY; TENSORS
Availability Source: Other Sources
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