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 Title: Observation of ortho-para dependence of pressure broadening coefficient in acetylene ν1+ν3 vibration band using dual-comb spectroscopy Author(s): Iwakuni, Kana Contributor(s): Yamada, Koichi MT; Sasada, Hiroyuki; Hong, Feng-Lei; Onae, Atsushi; Inaba, Hajime; Okubo, Sho Subject(s): Spectroscopy as an analytical tool Abstract: We observe that the pressure-broadening coefficients depend on the ortho-para levels. The spectrum is taken with a dual-comb spectrometer which has the resolution of 48 MHz and the frequency accuracy of 8 digit when the signal-to-noise ratio is more than 20\footnote{S. Okubo $et$ $al$., Applied Physics Express 8, 082402 (2015)}. \begin{wrapfigure}{r}{0pt} \includegraphics[scale=0.25]{Broadening coefficient 7-18.eps} \end{wrapfigure} In this study, about 4.4-Tz wide spectra of the $P$(31) to $R$(31) transitions in the \nub{1}+\nub{3} vibration band of \chem{^{12}C_2H_2} are observed at the pressure of 25, 60, 396, 1047, 1962 and 2654 Pa. Each rotation-vibration absorption line is fitted to Voight function and we determined pressure-broadening coefficients for each rotation-vibration transition. The Figure shows pressure broadening coefficient as a function of $m$. Here $m$ is $J”+1$ for $R$ and $–J”$ for $P$-branch. The graph shows obvious dependence on ortho and para. We fit it to Pade function considering the population ratio of three-to-one for the ortho and para levels. This would lead to detailed understanding of the pressure boarding mechanism. Issue Date: 2016-06-22 Publisher: International Symposium on Molecular Spectroscopy Genre: Conference Paper/Presentation Type: Text Language: En URI: http://hdl.handle.net/2142/91145 Rights Information: Copyright 2016 by the authors Date Available in IDEALS: 2016-08-22
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