RH12, 70th International Symposium on Molecular Spectroscopy THE CP-FTMW SPECTROSCOPY AND ASSIGNMENT OF THE MONO- AND DIHYDRATE COMPLEXES OF PERFLUOROPROPIONIC ACID G. S. Grubbs II, Daniel A. Obenchain, Derek S. Frank, Stewart E. Novick, S. A. Cooke, Agapito Serrato III, and Wei Lin RH12, 70th International Symposium on Molecular Spectroscopy June 22-26, 2015, Urbana, IL, USA

Motivation a Perfluorinated Carboxylic Acids (PFCAs) are commonly used as surfactants Have been detected in groundwater, lake water, wildlife, and human blood serum1 Wei came to Wesleyan with an interest in studying these interactions 1. B. F. Scott, C. A. Moody, C. Specer, J. M. Small, D. C. G. Muir, S. A. Mabury. Environ. Sci. Technol. 40 (2006) 6405.

Experiment Free Induction Decay Collected, Amplified and Digitized on a 40 GS/s oscilloscope Linear Frequency Sweep 0 – x - “Chirp” ν +/- x is amplified, pulsed and broadcast Center Frequency, ν, between 8-18 GHz Excitation interacts with the molecules To Diff. Pump

Experimental Details 97% PFPA purchased from Sigma-AldrichTM without further purification 1.5 atm Ar bubbled through sample ~40 cm upstream from Parker® Series 9 solenoid valve 8 μs chirps of 2 GHz regions 30,000 FID averages 7750-14250 MHz

Quantum Chemical Calculations

Results H2O-PFPA

Results (H2O)2-PFPA

Results (Comparison)

Results

Hydrating PFPA

Pcc Arguments H2O-TFA: B. Ouyang, T. G. Starkey, and B. J. Howard. J. Phys. Chem. A. 111 (2007) 6165. H2O-PFBA: J. Thomas, A. Serrato, III, W. Lin, W. Jäger, Y. Xu. Chem. Eur. J. 20 (2014) 6148.

Conclusions PFPA Hydration occurs in plane with the carboxylic acid group with hydrogens out of plane No tunneling Structure explained with Pcc arguments Submitted to J. Phys. Chem. A

Acknowledgements WL Welch Foundation SEN NSF Grant GSGII Missouri Research Board Grant Bob Bohn and Pete Pringle useful discussions