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 Title: GLOBAL ANALYSIS OF THE RADICAL ROTATIONAL, VIBRATIONAL AND ELECTRONIC TRANSITIONS Author(s): Coudert, L. H. Contributor(s): Pirali, Olivier ; Martin-Drumel, Marie-Aline Subject(s): Mini-symposium: Astrochemistry and Astrobiology in the age of ALMA Abstract: The \ce{NH2} radical, first observed by Herzberg and Ramsay,\footnote{Herzberg and Ramsay, {\em J.\ Chem.\ Phys.}~{\bf 20} (1952) 347} is dominated by a strong Renner-Teller effect\footnote{Dressler and Ramsay, {\em Phil.\ Trans.\ R.\ Soc.\ A}~{\bf 25} (1959) 553} giving rise to two electronic states: a bent $\tilde{X}\, ^2B_1$ ground state and a quasi-linear $\tilde{A}\, ^2A_1$ excited state. The \ce{NH2} radical has been the subject of numerous high-resolution investigations and its rotational, vibrational, and electronic transitions\footnote{\label{refs}Hadj Bachir, Huet, Destombes, and Vervloet, {\em J.\ Molec.\ Spectrosc.}~{\bf 193} (1999) 326; McKellar, Vervloet, Burkholder, and Howard, {\em ibid.}~{\bf142} (1990) 319; Morino and Kawaguchi, {\em ibid.}~{\bf 182} (1997) 428; and Martin-Drumel, Pirali, and Vervloet, {\em J.\ Phys.\ Chem.\ A}~{\bf 118} (2014) 1331} have been measured. In the most recent investigation,\textsuperscript{$c$} a value of the rotational quantum number $N$ as large as 26 could be reached and the line position analysis revealed that, even in the $\tilde{X}\, ^2B_1$ ground electronic state, an anomalous centrifugal distortion occurs and originates from the strong coupling between the overall rotation and the bending $\nu_2$ mode, as in the case of the water molecule.\footnote{Camy-Peyret and Flaud, {\em Molec.\ Phys.}~{\bf 32} (1976) 523} Two theoretical approaches accounting for the Renner-Teller effect are setup to compute the rovibronic energy levels of \ce{NH2}. The first one is an effective approach in which the large amplitude bending mode and the overall rotation are treated simultaneously.\footnote{Coudert, Gans, Garcia, and Loison, {\em J. Chem. Phys.}~{\bf 148} (2018) 054302} The second one is an exact approach, based on a tridimensional potential energy surface, in which all three vibrational modes are considered in addition to the overall rotation.\footnote{\label{moi}Coudert, Gans, Holzmeier, Loison, Garcia, Alcaraz, Lopes, and R\"oder, {\em J.\ Chem.\ Phys.}~{\bf 149} (2018) 224304} In the talk, both approaches will be tested fitting experimental high-resolution data pertaining to the \ce{NH2} radical. The first approach will be applied to data involving the ground and (010) vibrational states. The second approach should allow us to treat any vibrational states and to adjust the tridimensional potential energy surface of the radical.\footnote{Jensen, Odaka, Kraemer, Hirano and Bunker, {\em Spectrochim.\ Acta Part A}~{\bf 58} (2002) 763} Issue Date: 2019-06-20 Publisher: International Symposium on Molecular Spectroscopy Genre: Conference Paper / Presentation Type: Text Language: English URI: http://hdl.handle.net/2142/104282 DOI: 10.15278/isms.2019.RG09 Rights Information: Copyright 2019 L. H. Coudert Date Available in IDEALS: 2019-07-152020-01-25
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