A RIGOROUS COMPARISON OF THEORETICAL AND MEASURED CARBON DIOXIDE LINE INTENSITIES

Hodges, Joseph T.

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https://hdl.handle.net/2142/96820 Copy

Description

Title

A RIGOROUS COMPARISON OF THEORETICAL AND MEASURED CARBON DIOXIDE LINE INTENSITIES

Author(s)

Hodges, Joseph T.

Contributor(s)

• Tennyson, Jonathan
• Polyansky, Oleg
• Zak, Emil J
• Gameson, Lyn
• Fleisher, Adam J.
• Yi, Hongming

Issue Date

6/20/2017

Keyword(s)

Linelists

Abstract

The ability to calculate molecular line intensities from first principles plays an increasingly important role in populating line-by-line spectroscopic databases because of its generality and extensibility to various isotopologues, spectral ranges and temperature conditions. Such calculations require a spectroscopically determined potential energy surface, and an accurate dipole moment surface that can be either fully $textit{ab initio}$ $footnote{E. Zak et al., textit{J. Quant. Spectrosc. Radiat. Transf.} textbf{177}, (2016) 31.} footnote{Huang et al., textit{J. Quant. Spectrosc. Radiat. Transf.} textbf{130}, (2013) 134.}$ or an effective quantity based on fits to measurements $footnote{Tashkun et al., textit{J. Quant. Spectrosc. Radiat. Transf.} textbf{152}, (2015) 45.}$. Following our recent work where we used high-precision measurements of intensities in the (30013 $rightarrow$00001) band of $^{12}$C$^{16}$O$_2$ to bound the uncertainty of calculated line lists $footnote{Polyansky et al., textit{Phys Rev. Lett.} textbf{114}, (2015) 243001.}$, here we carry out high-precision, frequency-stabilized cavity ring-down spectroscopy measurements in the R-branch of the $^{12}$C$^{16}$O$_2$ (20012 $rightarrow$00001) band from J = 16 to 52. Gas samples consisted of 50 $mu$mol mol$^{-1}$ or 100 $mu$mol mol$^{-1}$ of nitrogen-broadened carbon dioxide with gravimetrically determined SI-traceable molar composition. We demonstrate relative measurement precision (Type A) at the 0.15 $%$ level and estimate systematic (Type B) uncertainty contributions in $%$ of: isotopic abundance 0.01; sample density, 0.016; cavity free spectral rang,e 0.03; line shape, 0.05; line interferences, 0.05; and carbon dioxide molar fraction, 0.06. Combined in quadrature, these components yield a relative standard uncertainty in measured line intensity less than 0.2 $%$ for most observed transitions. These intensities differ by more than 2 $%$ from those measured by Fourier transform spectroscopy and archived in HITRAN 2012 but differ by less than 0.5 $%$ with the calculations of Zak et al.

Publisher

International Symposium on Molecular Spectroscopy

Type of Resource

text

Language

English

Permalink

http://hdl.handle.net/2142/96820

DOI

10.15278/isms.2017.TJ02

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