The 65 th International Symposium on Molecular Spectroscopy

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The 65 th International Symposium on Molecular Spectroscopy, June 21 -25, 2010 Hydrated HCl

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

Solvation of HCl by Water + - more water added ? completely ionized •

Solvation of HCl by Water + - more water added ? completely ionized • How many water molecules are needed to dissociate HCl? • What are the structures of HCl-water clusters? • Role of hydrogen bonding?

Calculations of HCl-Water Clusters Packer, Clary, J. P. C. 1995 Sobolewski, Domcke, PCCP 2005

Calculations of HCl-Water Clusters Packer, Clary, J. P. C. 1995 Sobolewski, Domcke, PCCP 2005 Chaban, Gerber, Janda, JPCA 2001

Calculations of HCl-Water Clusters (12. 5) (0. 4) (w/ ZPE in k. J/mol) MP

Calculations of HCl-Water Clusters (12. 5) (0. 4) (w/ ZPE in k. J/mol) MP 2/aug-cc-p. VDZ (0) n=1 2 3 4 (-3. 2)

(HCl)m(H 2 O)n clusters in Ar matrix f-OH b-OH HCl Amirand, Maillard, J. Mol.

(HCl)m(H 2 O)n clusters in Ar matrix f-OH b-OH HCl Amirand, Maillard, J. Mol. Struct. 1988

FTIR spectra (HCl)m(H 2 O)n clusters in free jet HCl f-OH b-OH HCl Farnik,

FTIR spectra (HCl)m(H 2 O)n clusters in free jet HCl f-OH b-OH HCl Farnik, Wiemann, Suhm, JCP 2003 The clear assignment of the hydrated HCl with four water molecules is not still available through spectroscopy. Devlin, Farnik, Suhm, Buch, J. Phys. Chem. A, 2005

Laser Depletion Spectroscopy - Ultra Low Temp. (0. 37 K for 4 He) Closed-cycle

Laser Depletion Spectroscopy - Ultra Low Temp. (0. 37 K for 4 He) Closed-cycle refrigerator X-Y-Z HCl Pick-up Chamber LN 2 trap H 2 O pick-up cell Quadrupole Power meter Nozzle Main chamber ≈1 m Nd: YAG OPO/OPA 1064 nm, 750 m. J, 7 ns 2050 -6000 cm-1

IR Spectra of (HCl)m Clusters Spectral assignment of (HCl)n clusters up to n =

IR Spectra of (HCl)m Clusters Spectral assignment of (HCl)n clusters up to n = 6 Spectroscopists do it Cyclic structures up to the with frequency and hexamer intensity Frequency saturation for large clusters Skvortsov, Choi, Vilesov, JPCA 2007

Pick up of molecules by He droplets Abundance of Mn follows Poisson distribution: z

Pick up of molecules by He droplets Abundance of Mn follows Poisson distribution: z – average number of pickup collisions, linear with pickup pressure

Overview Spectra in He droplets Neat (HCl)m and (H 2 O)n clusters HCl b-OH

Overview Spectra in He droplets Neat (HCl)m and (H 2 O)n clusters HCl b-OH 3 m= 4 3 2 n= 2 2 54 1 Skvortsov, Choi, Vilesov, unpublished 2007 3+ 2 6 6 Mixed HCl and H 2 O clusters f-OH 2 1

Free OH-stretch bands in water and small HCl-H 2 O clusters <HCl> n≥ 3

Free OH-stretch bands in water and small HCl-H 2 O clusters <HCl> n≥ 3 <H 2 O> <HCl> <3> <1> <3> <2> <1> <2> * * <1> <0> <H 2 O> n=2 <0> <1> 2 HCl <1> <2> <0. 5> (H 2 O)2 H 2 O <0. 5>

Free OH-stretch bands in water and small HCl-H 2 O clusters HCl(H 2 O)2

Free OH-stretch bands in water and small HCl-H 2 O clusters HCl(H 2 O)2 HCl-H 2 O ? (HCl)2(H 2 O)2 Skvortsov, Choi, Vilesov, JPCA 2009

Free OH-stretch bands in water and larger HCl-H 2 O clusters Free OH bands

Free OH-stretch bands in water and larger HCl-H 2 O clusters Free OH bands of larger (HCl)m(H 2 O)n clusters are not resolved Skvortsov, Choi, Vilesov, JPCA 2009

Overview Spectra in He droplets Neat (HCl)m and (H 2 O)n clusters HCl Mixed

Overview Spectra in He droplets Neat (HCl)m and (H 2 O)n clusters HCl Mixed HCl and H 2 O clusters Skvortsov, Choi, Vilesov, unpublished 2007 b-OH f-OH

Bonded OH-stretch bands in water and (HCl)m(H 2 O)n clusters : Assignment in Progress

Bonded OH-stretch bands in water and (HCl)m(H 2 O)n clusters : Assignment in Progress 1 h: * 2 h: # <HCl> <H 2 O> <2> # * <1> * * * <2> <0. 35> <2> <0> 6 6 3 2 <2> (H 2 O)n <H 2 O> <HCl> # <1> <2> <0. 7> 5 4 2 w: * 3 w: # * <1> * # <3> * <2> 1 w<1> 1 w

Conclusions • (HCl)1(H 2 O)1 -3 and (HCl)2(H 2 O)1 clusters were identified by

Conclusions • (HCl)1(H 2 O)1 -3 and (HCl)2(H 2 O)1 clusters were identified by IR depletion spectroscopy using helium droplet matrix: Free OH stretching region • The congestion of the larger cluster bands makes the assignments of the clusters having more than 4 water molecules difficult

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

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