1. Perfluorobutyric acid and its monohydrate: a chirped pulse and cavity based Fourier transform microwave spectroscopic study Javix Thomas a, Agapito Serrato b, Wei Lin b, Wolfgang Jäger a, and Yunjie Xu a a Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada, T6G 2G2 b Department Chemistry and Environmental Sciences, The University of Texas at Brownsville, Brownsville, TX 78520 69 th International Symposium on Molecular Spectroscopy, 06/18/14

2. The ground-state structures of (a) HCl-H 2 O, (b) HNO 3 -H 2 O, (c) H 2 SO 4 - H 2 O, and (d) HNO 3 -(H 2 O) 2, all determined by rotational spectroscopy

3. The monohydrate, dihydrate and trihydrate of trifluoroacetic acid Ouyang et al J. Phy. Chem. 111 (2007) 6165-6175

4. The perfluobutyric acid (PFBA)

5. Experiment  University of Alberta chirped-pulse and cavity Fourier transform microwave spectrometers.  Scan range between 8 and 16 GHz (chirped-pulse) and 6 and 26 GHz (cavity).  Perfluorobutyric acid (98% Aldrich).  Helium (Neon) expansion gas at 2-6 bars backing pressure.  Line position error ± 50 kHz.

6. The Chirped-pulse FTMW spectrometer@Edmonton

7. The Chirped-pulse FTMW spectrometer at the University of Alberta

8. A portion of the spectrum of Perfluorobutyric Acid.

9. Comparison of the most stable conformers of the three short chain PFCAs

10. Another conformer of Perfluorobutyric Acid? Ellis et al J. Phy. Chem. 108 (2004) 10099-10106

11. A potential energy scan by rotating carboxyl group about the C1-C2 bond, i.e. dihedral angle  O4-C1-C2-C3, in steps of 15 degree at the MP2/6-311++G(2d,p) level

12. Spectroscopic constants

13. Centrifugal distortion constants of the first four perfluocarboxylic acids CF 3 COOH a CF 3 CF 2 COOH b CF 3 CF 2 CF 2 COOHCF 3 CF 2 CF 2 COOH c D J /kHz0.9660(217)0.245(4)0.0221(3)0.003(1) D JK /kHz-0.938(62)0.40(2)0.012(2)N/A D K /kHz0.466(61)-0.44(1)0.041(3)0.26(5) d 1 /kHz-0.0483(69)0.012(3)-0.0012(2)N/A d 2 /kHz0.3471(51)-4.3(1)-0.0012(2)N/A a Ouyang et al J. Phy. Chem. 111 (2007) 6165. b Grubbs et al J. Mol. Spectrosc. 275 (2012) 1. c Pejlovas et al submitted to Chem. Phys. Lett.

14. Perfluorobutyric acid-water complex Urata et al Phy. Chem. Chem. Phy. 6 (2004) 3325-3332 Optimized geometry at the B3LYP/6-31þG* level with fixing the intra- geometry of each monomer.

15. Perfluorobutyric acid-water complex ParameterPFBA--H 2 O-IPFBA--H 2 O-II PFBA--H 2 O-III ∆D e [a] 00.11 32.3 ∆D 0 [a] 00.07 28.7 A1305 878 B410 586 C395 476 |μ a |2.903.70 0.60 |μ b |1.810.06 3.30 |μ c |0.990.58 0.44

16. Spectroscopic constants

17. Conclusion High resolution rotational spectra of PFBA and its monohydrate were studied for the first time using chirped pulse and cavity based Fourier transform spectroscopies. One PFBA conformer and One PFBA monohydrate conformer were conclusively identified experimentally. This monohydrate conformer was shown to behave well as a semirigid rotor and adopt a unique orientation for the nonbonded water H atom, in contrast to other smaller acid--water complexes studied using rotational spectroscopy where large amplitude motions and tunnelling motions are significant. Javix Thomas et. al. Chem. Eur. J. 20(20) (2014) 6148

18. Acknowledgement The University of Alberta and the Natural Sciences and Engineering Research Council (NSERC) of Canada for WJ or YX Olegario Vazquez Rana Faculty Fellowship, UT Brownsville and the Welch Foundation for WL