Ground and low-lying excited states of propadienylidene H2C=C=C: obtained by negative ion photoelectron spectroscopy

Stanton, John F. and Garand, Etienne and Kim, Jongjin and Yacovitch, Tara I. and Hock, Christian and Case, Amanda S. and Miller, Elisa M. and Lu, Yu-Ju and Vogelhuber, Kristen M. and Wren, Scott W. and Ichino, Takatoshi and Maier, John P. and McMahon, Robert J. and Osborn, David L. and Neumark, Daniel M. and Lineberger, Carl W.. (2012) Ground and low-lying excited states of propadienylidene H2C=C=C: obtained by negative ion photoelectron spectroscopy. Journal of Chemical Physics, 136 (13). p. 134312.

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Official URL: http://edoc.unibas.ch/dok/A6070315

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A joint experimental-theoretical study has been carried out on electronic states of propadienylidene (H2CCC), using results from negative-ion photoelectron spectroscopy. In addition to the previously characterized X̃1A1 electronic state, spectroscopic features are observed that belong to five additional states: the low-lying ã3B1 and b̃3A2 states, as well as two excited singlets, Ã1A2 and B̃1B1, and a higher-lying triplet, c̃3A1. Term energies (T0, in cm−1) for the excited states obtained from the data are: 10 354±11 (ã3B1); 11 950±30 (b̃3A2); 20 943±11 (c̃3A1); and 13 677±11 (Ã1A2). Strong vibronic coupling affects the Ã1A2 and B̃1B1 states as well as ã3B1 and b̃3A2 and has profound effects on the spectrum. As a result, only a weak, broadened band is observed in the energy region where the origin of the B̃1B1 state is expected. The assignments here are supported by high-level coupled-cluster calculations and spectral simulations based on a vibronic coupling Hamiltonian. A result of astrophysical interest is that the present study supports the idea that a broad absorption band found at 5450 Å by cavity ringdown spectroscopy (and coincident with a diffuse interstellar band) is carried by the B̃1B1 state of H2CCC.
Faculties and Departments:05 Faculty of Science > Departement Chemie > Former Organization Units Chemistry > Physikalische Chemie (Maier)
UniBasel Contributors:Maier, John Paul
Item Type:Article, refereed
Article Subtype:Research Article
Publisher:AIP Publishing
Note:Publication type according to Uni Basel Research Database: Journal article
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Last Modified:24 Apr 2017 09:36
Deposited On:01 Mar 2013 11:12

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