1. Gyeongsang National University, Jinju, Korea Myong Yong Choi, Seung Jun Lee Hydrated HCl Complexes, (HCl) m (H 2 O) n, in Helium Nanodroplets: HCl Stretching Modes The 65 th International Symposium on Molecular Spectroscopy, June 21-25, 2010 University of Southern California, Los Angeles, CA 90089, U.S.A. Dimitry Skvortsov and Andrey F. Vilesov ( ) m ( ) n

2. (-3.2) (w/ ZPE in kJ/mol) MP2/aug-cc-pVDZ (12.5) (0.4) (2.5) (0) n = 12 3 4 Calculations of HCl-Water Clusters The clear assignment of the hydrated HCl with four water molecules is not still available through spectroscopy.

3. Calculated spectra of HCl-(H 2 O) n MP2/aug-cc-pVDZ H3O+H3O+ b-OH f-OH HCl b-OH (H 2 O) n 5432

4. Science, 324, 1545 (2009) Recent assignment of the S5 band in He droplets to H 3 O + -(H 2 O) 3 -Cl - + - Tiny droplets of acid. (Credit: Image courtesy of Ruhr- Universitaet-Bochum) S5

5. m/z=73 Recent assignment of the S5 band in He droplets to H 3 O + -(H 2 O) 3 -Cl - + - (HCl) m (H 2 O) n n=4 m=1 n=10 S5 Science, 324, 1545 (2009)

6. Laser Depletion Spectroscopy m/e > 6

7. Overview Spectra in He droplets Neat (HCl) m and (H 2 O) n clusters Mixed HCl and H 2 O clusters Skvortsov, Choi, Vilesov, unpublished 2007 HClb-OHf-OH S5

8. IR Spectra of (HCl) m Clusters Skvortsov, Choi, Vilesov, JPCA 2007 m = (HCl) 1 (H 2 O) 1

9. Assignment of the clusters (HCl) m (H 2 O) n using pressure dependence of the band intensity ratios: I n /I 1 n is somewhat less than integer Sub-linear dependence at large Z: - droplet size distribution, - decreasing of the droplet size - scattering of the beam - downstream pickup According to Poisson dependence: Log(I n /I 1 ) = (n-1)*Log(Z) + f(n) n – Cluster size Z – Average number of collisions or pickup pressure Water: difficult to reach zero pressure, Important, because otherwise Poisson does not work and interpretation of the pickup pressure results is ambiguous Neat and mixed HCl and H 2 O clusters Skvortsov, Choi, Vilesov, unpublished 2007 HCl-H 2 O *

10. IR Spectra of (HCl) m Clusters Skvortsov, Choi, Vilesov, JPCA 2007 m = Log(I m /I 1 ) = (m-1)*Log(Z) + f(m)

11. Overview Spectra in He droplets Mixed HCl and H 2 O clusters Neat (HCl) m and (H 2 O) n clusters Skvortsov, Choi, Vilesov, unpublished 2007 HClb-OHf-OH m = 4 2 3 1 2 n = 6 6 5432 1 2 2 3+

12. Calculated spectra of HCl-(H 2 O) n MP2/aug-cc-pVDZ H3O+H3O+ b-OH f-OH HCl b-OH (H 2 O) n 5432

13. HCl-stretch bands in (HCl) m (H 2 O) n clusters at different Z(HCl) Slope: 0.83 m = 2 Slope: 1.72 m = 3 S5

14. HCl-stretch bands in (HCl) m (H 2 O) n clusters at different Z(H 2 O) S5

15. Assignment of the H-Cl stretching bands 2:2 HCl:H 2 O 2:04:03:02:0 In gas Farnik, Wiemann, Suhm, JCP 2003 S3 1:1 S2 NA S5 NA S4 NA S9 NA S6 NA S1 2:1 S8 2:1 S7 NA S10 1:2 2:1 overlapped with 4:0 1:1 2:1 1:2 or 2:2 3:1 ? ? S5 (HCl) m = O X

16. 1.88 D 6.26 D ++ + _____ ++ 2 1 0o0o 90 o VTMA +5 o 2 0o0o 90 o VTMA +5 o 1

17. ++ + _____ ++ 1 2 44 0 [NH 2 (AS)] 42 0 [N9H] 80 0 [N1H] 31 0 [NH 2 (SS)] 29 0 [NH 2 (AS)] 73 0 [N7H] 47 0 [N1H] 83 0 [NH 2 (SS)] Electric Field Dependence of Different Dipoles 1.88 D 6.26 D 1.88 D 31 0 [NH 2 (SS)] 29 0 [NH 2 (AS)] M. Y. Choi and R. E. Miller, J. Am. Chem. Soc. 2006, 128, 7320.

18. Predicted electric field dependence of the H 3 O + -(H 2 O) 3 -Cl - band S. Flynn, A. Morrison, T. Liang, G. Douberly, unpublished result (2010) E Stark E Laser E Stark E Laser Values used to reproduce Experimental field dependence:  p = 2.76 D, VTMA = 58.2 O  p = 2.76 D VTMA = 58.4 O  p = 4.22 D VTMA = 36.5 O Symmetric stretch

19. Conclusions - Observation of sharp infrared spectrum of [H(H 2 O) 4 ] + Cl - seems illusive - Calculated spectra may be at large variance with experiment - Need for more Mutual Tests between Theory and Experiment

20. Acknowledgements Andrey F. Vilesov Group at USC GNU Laser Spectroscopy Lab.

21. m/z=73 Recent assignment of the S5 band in He droplets to H 3 O + -(H 2 O) 3 -Cl - + - (HCl) m (H 2 O) n n=4 m=1 n=10 M=108: ?? (HCl) 1 (H 2 O) 4 or (HCl) 2 (H 2 O) 2 Science, 324, 1545 (2009)