Retrieval of methanol absorption parameters at terahertz frequencies using multispectral fitting

• Published in: Journal of molecular spectroscopy Vol. 318; pp. 12 - 25
• Main Authors: Slocum, David M., Xu, Li-Hong, Giles, Robert H., Goyette, Thomas M.
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 01.12.2015
• Subjects: Intensities; Methanol; Multispectral fitting; Pressure broadening; Pressure shift; Terahertz; Pressure broadening; Terahertz; Pressure shift; Intensities; Multispectral fitting; Methanol
• ISSN: 0022-2852; 1096-083X
• DOI: 10.1016/j.jms.2015.09.008

[Display omitted] •Multispectral analysis of methanol at varying pressures.•Observed 221 spectral features from 1.480 to 1.495THz.•Retrieved position, intensity, broadening, and shifting parameters for all features.•Assigned spectrum from and compared results with JPL database. A high-resolution broadband study of the methanol absorption spectrum was performed at 1.480–1.495THz. The transmittance was recorded under both self- and air-broadening conditions for multiple pressures at a resolution of 500kHz. A multispectral fitting analysis was then performed. The transition frequency, absolute intensity, self- and air-broadening coefficients, and self- and air-induced pressure shifts were retrieved for 221 absorption lines using the multispectral fitting routine. Observed in the data were two different series of transitions, both a b-type Q-branch with K=-7←-6 and an a-type R-branch with J=31←30. The retrieved frequency position values were compared with values from spectral databases and trends within the different series were identified. An analysis of the precision of the fitting routine was also performed.