1. Galen Sedo, Jane Curtis, Kenneth R. Leopold Department of Chemistry, University of Minnesota The Dipole Moment of the Sulfuric Acid Monomer

2. Sulfuric Acid Aerosols A principle source of sulfate-containing atmospheric particles High affinity for water and a high rate of nitrogen species uptake Investigating Sulfuric Acid Systems Nucleation Theory Homogeneous and Heterogeneous particle growth Ion-induced and ion-mediated nucleation theory Charge-dipole interactions

3. H 2 SO 4 b 2.725(15) D H 2 SO 4 -H 2 O a 3.052(17) D a)Brauer, C. S.; Sedo, G.; Leopold, K. R. Geophys. Res. Lett. 33 (2006) L23805, doi:10.1029/2006GL028110. b)Kuczkowski, R. L.; Suenram, R. D.; Lovas, F. J. Journal of the American Chemical Society 1981, 103, 2561. Previous Dipole Moment Work

4. H 2 SO 4 b 2.725(15) D 2.817 D H 2 SO 4 -H 2 O a 3.052(17) D 2.147 D a)Brauer, C. S.; Sedo, G.; Leopold, K. R. Geophys. Res. Lett. 33 (2006) L23805, doi:10.1029/2006GL028110. b)Kuczkowski, R. L.; Suenram, R. D.; Lovas, F. J. Journal of the American Chemical Society 1981, 103, 2561. c)Al Natsheh, A; Nadykto, A. B.; Mikkelsen, K. V.; Yu, F.; Ruuskanen, J. J. Phys. Chem. A 2004, 108, 8914. Previous Dipole Moment Work PW91PW91/TZP c 0.905 D (29.7 %) -0.092 D (-3.4 %)

5. H 2 SO 4 b 2.725(15) D 2.817 D 3.147 D H 2 SO 4 -H 2 O a 3.052(17) D 2.147 D 2.965 D a)Brauer, C. S.; Sedo, G.; Leopold, K. R. Geophys. Res. Lett. 33 (2006) L23805, doi:10.1029/2006GL028110. b)Kuczkowski, R. L.; Suenram, R. D.; Lovas, F. J. Journal of the American Chemical Society 1981, 103, 2561. c)Al Natsheh, A; Nadykto, A. B.; Mikkelsen, K. V.; Yu, F.; Ruuskanen, J. J. Phys. Chem. A 2004, 108, 8914. Previous Dipole Moment Work PW91PW91/TZP c 0.905 D (29.7 %) -0.092 D (-3.4 %) 0.087 D (2.9 %) -0.692 D (-25.4 %) MP2/aug-cc-pVQZ a

6. MirrorMirror Antenna Argon passed over a sample of polymerized SO 3 Backing Pressure 25 psig Microwave Electronics Computer Spectrum Fabry-Perot Cavity Diffusion Pump Pulsed Nozzle MirrorMirror The Pulsed Nozzle FTMW Spectrometer

7. MirrorMirror Antenna Argon passed over a sample of polymerized SO 3 Backing Pressure 25 psig Microwave Electronics Computer Spectrum Fabry-Perot Cavity Diffusion Pump Pulsed Nozzle MirrorMirror The Pulsed Nozzle FTMW Spectrometer Series 9 Pulsed Solenoid Valve Needle Adaptor Stainless Steal Needle Dimensions ID = 0.016"Length = 0.205" Argon bubbled through H 2 O at a rate of 10 sccm.

8. Diffusion Pump Fabry-Perot Cavity The Pulsed Nozzle FTMW Spectrometer MirrorMirror Fabry-Perot Cavity Diffusion Pump MirrorMirror

9. Fabry-Perot Cavity The Pulsed Nozzle FTMW Spectrometer 1.A potential of up to 10,000 V (5,000 V/plate) 2.Calibrated the plate spacing before and after collecting data using the Ar-SO 3 complex [  = 0.2676(3) D] Checked the calibration method using OCS  lit = 0.7152(2) D  obs = 0.7157(16) D

10. Zero Field and 37 Stark-shifted Frequencies The  M = 0 Stark Component of the 1 10 ← 0 00 Transition 10184.25010185.25010186.250 Frequency [MHz]  = 0 V/cm  = 76.5 V/cm  max = 1.749 MHz  max = 122.3 V/cm

11. Zero Field and 54 Stark-shifted Frequencies  max = 1.721 MHz  max = 183.5 V/cm  = 0 V/cm  = 76.5 V/cm 10184.25010185.250 10186.250 Frequency [MHz] The  M| = 1 Stark Component of the 1 10 ← 0 00 Transition

12. a)Kuczkowski, R. L.; Suenram, R. D.; Lovas, F. J. “Microwave Spectrum, Structure, and Dipole Moment of Sulfuric Acid.” Journal of the American Chemical Society 1981, 103, 2561-2566. Sulfuric Acid Molecular Constants a

13. a)Kuczkowski, R. L.; Suenram, R. D.; Lovas, F. J. “Microwave Spectrum, Structure, and Dipole Moment of Sulfuric Acid.” Journal of the American Chemical Society 1981, 103, 2561-2566. Sulfuric Acid Transition Frequencies a

14. H = H rot + H Q + H  H  = -    c =  tot = 2.9643(67) D H = H rot + H Q + H  H  = -   1 10 ← 0 00  c =  tot = 2.9643(67) D 6 43 ← 5 33  c =  tot = 2.725(15) D  = (a c + b c M 2 )  2  c 2 a c = 2.4048 x 10 -8 b c = -3.8759 x 10 -6 6 43 ← 5 33  c =  tot = 2.725(15) D

15. 6 43 ← 5 33 Stark Coefficients y = -3.3742E-05x – 4.6141E-04 R 2 = 1.0000 y = 2.112E-07x – 5.694E-05 R 2 = 1.000 6 43 ← 5 33  c =  tot = 2.725(15) D  a c = 2.4048 x 10 -8 b c = -3.8759 x 10 -6 1 10 ← 0 00  c =  tot = 2.9643(67) D  a c = 2.4032 x 10 -8 b c = -3.8640 x 10 -6

16. Error Analysis Three Primary Sources of Experimental Error 1.Least Squares Analysis  ls = 2.96434 D  ls = 0.00023 D

17. Three Primary Sources of Experimental Error 1.Least Squares Analysis  ls = 2.96434 D  ls = 0.00023 D 2.Plate Spacingd plate = 32.702 cm  plate = 0.064 cm Error Analysis

18. Three Primary Sources of Experimental Error 1.Least Squares Analysis  ls = 2.96434 D  ls = 0.00023 D 2.Plate Spacingd plate = 32.702 cm  plate = 0.064 cm 3.Calibration Standard  Ar-SO3 = 0.2676 D  Ar-SO3 = 0.0003 D

19. This Work2.9643(67) D Kuczkowski, Suenram, & Lovas2.725(15) D 0.239 D Comparison of the Experimental and Theoretical Dipole Moments PW91PW91/aug-cc-pV(Q+d)Z2.9520 D MP2/aug-cc-pV(Q+d)Z3.4416 D

20. Comparison of the Experimental and Theoretical Dipole Moments This Work2.9643(67) D PW91PW91/aug-cc-pV(Q+d)Z2.9520 D MP2/aug-cc-pV(Q+d)Z3.4416 D Brauer et al.3.052(17) D PW91PW91/aug-cc-pVQZ2.407 D MP2/aug-cc-pVQZ * 2.965 D H 2 SO 4 H 2 SO 4 -H 2 O * Single-point calculation done at the aug-cc-pVTZ geometry, taken from Brauer et al.

21. Conclusions 1.The dipole moment of the sulfuric acid monomer has been refined using Fourier transform microwave spectroscopy. 91 Stark-shifted frequencies were collect for the 1 10 ← 0 00 rotational transition. The newly measured value, 2.9643(67) D, represents an increase of approximately 0.24 D over the previously published value. 2.The dipole moments of the sulfuric acid monomer and mono-hydrate were calculated using both ab initio and Density Functional Theory. The calculated dipole moments show convergence with increasing basis set size. The agreement between the measured experimental values and those of theory various drastically with the method employed.

22. Dr. Kenneth Leopold Jane Curtis Dr. Carolyn Brauer Acknowledgements Funding National Science Foundation (NSF) Petroleum Research Fund (PRF) Minnesota Supercomputing Institute (MSI)