Atom-specific vibrational analysis reveals labile bonds in linear and branched PFOA molecules
Abstract
We have performed atom-specific vibrational analyses of a large number of perfluorooctanoic acid isomers as well as their anions and show that differences in the vibrational features of corresponding anion and neutral molecules clearly identify the C–F bonds that are most strongly activated in the anions. We discuss two analysis tools for associating vibrational modes with individual atoms, both based on density functional theory calculations. The first involves computing the Einstein frequencies for a given atom and the second projects the full vibrational spectrum onto a given atom using participation factors derived from the normal mode eigenvectors. We show that the two methods give results that are qualitatively the same and that either can be used to identify the most labile C–F bonds in the anions. We also show that the results of the vibrational analyses are consistent with systematically computed F atom removal energies. The vibrational analysis tools are shown to be related to the local mode analysis of Cremer and co-workers. Finally, we compare and contrast branched and linear PFAS molecules and analogous hydrogenated carbon chains.
Article Details
Journal Info
The Journal of Chemical Physics
American Institute of Physics
Authors (12)
Jesús N. Pedroza-Montero
Department of Physics, Central Michigan University 1 , Mt Pleasant, Michigan 48859,
Kushantha P. K. Withanage
Department of Physics, University of Texas at El Paso 2 , El Paso, Texas 79968,
Anri Karanovich
Department of Physics, Central Michigan University 1 , Mt Pleasant, Michigan 48859,
Pardeep Kaur
Department of Physics, University of Texas at El Paso 2 , El Paso, Texas 79968,
Yoh Yamamoto
Department of Physics, University of Texas at El Paso 2 , El Paso, Texas 79968,
Sonam C. Lhamo
Department of Physics, University of Texas at El Paso 2 , El Paso, Texas 79968,
Jenna A. Bilbrey
Physical Detection Systems and Deployment Division, Pacific Northwest National Laboratory 3 , Richland, Washington 99352,
Eric J. Bylaska
Physical Sciences Division, Pacific Northwest National Laboratory 4 , Richland, Washington 99354,
Karol Kowalski
Pacific Northwest National Laboratory, Physical Sciences Division 1 , Richland, Washington 99354,
Tunna Baruah
Department of Physics, University of Texas at El Paso 2 , El Paso, Texas 79968,
Mark R. Pederson
Department of Physics, University of Texas at El Paso 2 , El Paso, Texas 79968,
Koblar A. Jackson
Department of Physics and Science of Advanced Materials Program