High-temperature mid-infrared absorption spectra of methanol (CH3OH) and ethanol (C2H5OH) between 930 and 1170 cm-1. (February 2019)

• Record Type: Journal Article
• Authors: Ding, Y.; Strand, C.L.; Hanson, R.K.
• Is Part Of: Journal of quantitative spectroscopy & radiative transfer. Volume 224(2019)
• Page Start: 396
• Page End: 402
• Publication Date: 2019-02
• Subjects: Methanol -- Ethanol -- Shock tube -- High-temperature -- Mid-infrared -- Absorption spectra; Spectrum analysis -- Periodicals; Radiation -- Periodicals; Analyse spectrale -- Périodiques; Rayonnement -- Périodiques; Radiation; Spectrum analysis; Periodicals; 543.0858
• DOI: 10.1016/j.jqsrt.2018.11.034
• Languages: English
• ISSNs: 0022-4073

Abstract

Highlights: Reported the high-temperature absorption spectra for methanol and ethanol near 10 µm. Significant temperature dependence was discovered in the spectra for both species. Results were compared against existing spectroscopic models and large discrepancies were found at elevated temperatures. Indicated the necessity for considering high-J ro-vibrational transitions and hotbands for high-temperature application purposes. Abstract: A methodology was recently developed with a broad-tuning, rapid-scan external-cavity quantum-cascade-laser in conjunction with shock tube facilities to measure the high-temperature mid-infrared absorption spectra of gaseous molecules. This technique is deployed to measure the cross section profiles in the C-O stretching band for methanol (CH3 OH) and ethanol (C2 H5 OH) between 930 and 1170 cm -1 . Methanol spectra are presented from 620 to 1304K between 0.98-3.30 atm with distinctive P, Q, and R branches of the ν 8 vibrational band. At elevated temperatures, the emergence of hotbands and high-J ro-vibrational transitions are clearly observed. The absorption cross sections of ethanol are measured from 296 to 1018K between 0.90-3.27 atm. The peak strength decreases with temperature, with the peak location shifting to lower wavenumbers. These measurements are compared with existing empirical models, illustrating a strong need for the development of a high-temperature spectroscopic database.