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 Title: Roaming and spectroscopy Author(s): Bowman, Joel Subject(s): Mini-symposium: Spectroscopy in Kinetics and Dynamics Abstract: Accurate ab initio theoretical/computational work on dynamics and spectroscopy begins with a potential energy surface (PES). My talk therefore begins with a brief review of progress we have made in developing accurate ab initio global PESs for reaction dynamics. “Roaming” is an unusual alternate pathway to reaction products that was found in the unimolecular dissociation of H$_2$CO by running roughly 100 000 trajectories on such a PES. The signatures of roaming were seen in the spectroscopic detection of the rotational states of CO correlated with translational energy distribution of the H$_2$. I will discuss roaming in NO$_3$ photodissociation to NO+O$_2$ and give a short history of the topic. In particular I will recount how poor Franck-Condon factors in pioneering LIF detection experiments in 1997 of the low-lying vibrational states of O$_2$ plus the assumption of a “prior” vibrational distribution led to the wrong conclusions about the O$_2$ vibrational-state distribution. Later more sophisticated experiments obtained the correct vibrational distribution, which led to the (correct) speculation about roaming in this system. I conclude with some comments about roaming wavefunctions and will wonder aloud about ways to detect wavefunctions spectroscopically. (Roaming wavefunctions have been reported by Hua Guo and co-workers for the MgH$_2$.) Issue Date: 2014-06-16 Publisher: International Symposium on Molecular Spectroscopy Citation Info: Bowman, J. ROAMING AND SPECTROSCOPY. Proceedings of the International Symposium on Molecular Spectroscopy, Urbana, IL, June 16-21, 2014. DOI: 10.15278/isms.2014.MH01 Genre: Conference Paper / Presentation Type: Text Language: English URI: http://hdl.handle.net/2142/55844 DOI: https://doi.org/10.15278/isms.2014.MH01 Rights Information: Copyright 2014 by the authors. Licensed under a Creative Commons Attribution 4.0 International License. http://creativecommons.org/licenses/by/4.0/ Date Available in IDEALS: 2014-11-202015-04-14
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