1. Georg-August-Universitaet Goettingen Tobias N. Wassermann Institute of Physical Chemistry Goettingen 19/06/2006 61st Ohio State University Symposium on Molecular Spectroscopy Proton tunneling estimates for malonaldehyde vibrations from supersonic jet and matrix quenching experiments Tobias N. Wassermann, Martin A. Suhm Institute of physical chemistry, University of Goettingen, Tammannstr. 6, D-37077 Goettingen, Germany David Luckhaus Chemistry Departement, University of British Columbia, 6174 University Blvd., Vancouver, BC, Canada Stéphane Coussan Lab. Physique des Interactions Ioniques et Moléculaires, UMR 6633, University of Marseille, Centre St-Jérôme, 13397 Marseille Cedex 20, France

2. Tobias N. Wassermann Institute of Physical Chemistry Goettingen 61st Ohio State University Symposium on Molecular Spectroscopy 2 19/06/2006 Proton tunneling estimates for malonaldehyde vibrations Outline  Introduction  Experimental setup  Method of evaluation of the tunneling splittings  Comparison with acetylacetone  Spectra and results  Summary, conclusions  Acknowledgement

3. Tobias N. Wassermann Institute of Physical Chemistry Goettingen 61st Ohio State University Symposium on Molecular Spectroscopy 3 19/06/2006 Proton tunneling estimates for malonaldehyde vibrations Malonaldehyde Stable in the enol form two equivalent C S –structures  double minimum potential tunneling splitting between the two wells

4. Tobias N. Wassermann Institute of Physical Chemistry Goettingen 61st Ohio State University Symposium on Molecular Spectroscopy 4 19/06/2006 Proton tunneling estimates for malonaldehyde vibrations Tunneling splitting in the ground state is known with high accuracy  E 0 = 21.58 cm -1 [1] Changes of splittings in vibrationally excited states are difficult to measure Only two known examples: 14 = 512 cm -1 :  (  E)≈ -6 cm -1 [2] 6 = 1594 cm -1 :  (  E)= -0.03 cm -1 [3] [1] : S. L. Baughcum, Z. Smith, E. B. Wilson, R. W. Duerst, J. Am. Chem. Soc., 106(8), 2260, 1984 D. W. Firth, K. Beyer, M. A. Dvorak, S. W. Reeve, A. Grushow, K. R. Leopold, J. Chem. Phys., 94(3), 1812, 1991 T. Baba, T. Tanaka, I. Morino, K. M. T. Yamada, K. Tanaka, J. Chem. Phys., 110(9), 4131, 1999 [2] : C. J. Seliskar, R. E. Hoffman, J. Mol. Spectrosc., 96, 146, 1982 [3] : C. Duan, D. Luckhaus, Chem. Phys. Lett., 391, 129, 2004

5. Tobias N. Wassermann Institute of Physical Chemistry Goettingen 61st Ohio State University Symposium on Molecular Spectroscopy 5 19/06/2006 Proton tunneling estimates for malonaldehyde vibrations T. D. Sewell, Y. Guo, D. L. Thompson, J. Chem. Phys., 103(19), 8557, 1995 semiclassical V. A. Benderskii, E. V. Vetoshkin, I. S. Irgibaeva, H.-P. Trommsdorff, Russ. Chem. Bull, Int. Ed., 50(7), 1148, 2001 instanton trajectory D. Tew, N. C. Handy, S. Carter, S. Irle J. Bowman, Molec. Phys., 102(21-22), 2217, 2004 quantum state calculations R. Meyer, T.K. Ha, Molec. Phys., 101(22), 3263, 2003 quantum state calculations

6. Tobias N. Wassermann Institute of Physical Chemistry Goettingen 61st Ohio State University Symposium on Molecular Spectroscopy 6 19/06/2006 Proton tunneling estimates for malonaldehyde vibrations Experimental Setup Filet-Jet: Fine but lengthy 600 x 0.2 mm 6 magnetic valves High throughput MA does not form H-bonded clusters

7. Tobias N. Wassermann Institute of Physical Chemistry Goettingen 61st Ohio State University Symposium on Molecular Spectroscopy 7 19/06/2006 Proton tunneling estimates for malonaldehyde vibrations Carrier Gases Helium like free molecules in the gas phase at low temperatures Argon lower expansion-temperature higher polarizability may condense on the molecules  Amorphous flying Ar-Nano- matrices  Spectra comparable with crystalline matrix

8. Tobias N. Wassermann Institute of Physical Chemistry Goettingen 61st Ohio State University Symposium on Molecular Spectroscopy 8 19/06/2006 Proton tunneling estimates for malonaldehyde vibrations Rotational temperatures in the jet: 20 – 60 K. Boltzmann distribution  ~ 1 2

9. Tobias N. Wassermann Institute of Physical Chemistry Goettingen 61st Ohio State University Symposium on Molecular Spectroscopy 9 19/06/2006 Proton tunneling estimates for malonaldehyde vibrations Molecular symmetry group G 4 if … is not seen in the spectra  any splitting in spectra indicates a vibrational dependence of the tunneling splitting C. J. Seliskar, R. E. Hoffman, J. Mol. Spectrosc., 96, 146, 1982

10. Tobias N. Wassermann Institute of Physical Chemistry Goettingen 61st Ohio State University Symposium on Molecular Spectroscopy 10 19/06/2006 Proton tunneling estimates for malonaldehyde vibrations A side glance … Acetylacetone R. Srinivasan, J. S. Feenstra, S. T. Park, S. Xu, A. H. Zewail, J. Am. Chem. Soc., 126, 2266, 2004 Tunneling splitting not detected! W. Caminati, J.-U. Grabow, J. Am. Chem. Soc., 128(3), 854, Jan. 2006 CSCS

11. Tobias N. Wassermann Institute of Physical Chemistry Goettingen 61st Ohio State University Symposium on Molecular Spectroscopy 11 19/06/2006 Proton tunneling estimates for malonaldehyde vibrations Ar-matrix, AcAc/Ar=2/1000 N 2 -matrix, AcAc/N 2 =4/1000 Jet He

12. Tobias N. Wassermann Institute of Physical Chemistry Goettingen 61st Ohio State University Symposium on Molecular Spectroscopy 12 19/06/2006 Proton tunneling estimates for malonaldehyde vibrations N 2 -matrix, AcAc/N 2 =4/1000 Ar-matrix, AcAc/Ar=2/1000 Jet He Jet N 2 Jet Ar Only small matrix shifts in Acetylacetone (≤ 3 cm -1 )  Conclusion: any major matrix shifts in Malonaldehyde are caused by quenching of the tunneling motion

13. Tobias N. Wassermann Institute of Physical Chemistry Goettingen 61st Ohio State University Symposium on Molecular Spectroscopy 13 19/06/2006 Proton tunneling estimates for malonaldehyde vibrations Quenching of the tunneling in a matrix Direct Proton transfer: no longer a symmetrical double minimum Symmetrical tunneling path: includes transfer of the heavy Ar atom

14. Tobias N. Wassermann Institute of Physical Chemistry Goettingen 61st Ohio State University Symposium on Molecular Spectroscopy 14 19/06/2006 Proton tunneling estimates for malonaldehyde vibrations  CH at 767 cm -1 : one band that shifts by only about 1 cm -1 vibration does not affect proton transfer out of plane C-H bending mode

15. Tobias N. Wassermann Institute of Physical Chemistry Goettingen 61st Ohio State University Symposium on Molecular Spectroscopy 15 19/06/2006 Proton tunneling estimates for malonaldehyde vibrations  OH out of plane O-H bending Jet:  E 1 = 4.1 cm -1 Matrix Comparison:  E 1 = 4.8 cm -1 Tunneling temperature:10 – 20 K

16. Tobias N. Wassermann Institute of Physical Chemistry Goettingen 61st Ohio State University Symposium on Molecular Spectroscopy 16 19/06/2006 Proton tunneling estimates for malonaldehyde vibrations CO at 1594 cm -1 : symmetric combination of C=C/C=O stretching with OH in plane bending from hi-res. spectroscopy:  (  E)= - 0.03 cm -1 C. Duan, D. Luckhaus, Chem. Phys. Lett., 391, 129, 2004 this work: He jet – Ar jet:  (  E)= - 1.4 cm -1 He jet – Ar matrix:  (  E)= - 3.2 cm -1 Error: 3 cm -1  tunnel splittings with ± 6 cm -1 ≈ 0 cm -1

17. Tobias N. Wassermann Institute of Physical Chemistry Goettingen 61st Ohio State University Symposium on Molecular Spectroscopy 17 19/06/2006 Proton tunneling estimates for malonaldehyde vibrations  OH in plane OH bending, CH bending, CC stretching Jet:  E 1 = 9.9 cm -1 Matrix Comparison:  E 1 = 8.2 cm -1

18. Tobias N. Wassermann Institute of Physical Chemistry Goettingen 61st Ohio State University Symposium on Molecular Spectroscopy 18 19/06/2006 Proton tunneling estimates for malonaldehyde vibrations Summary and Conclusions  New results for tunneling splittings of malonaldehyde vibrations have been obtained  Comparison of gas phase, jet and matrix spectra leads to excited state splittings  Accuracy is limited by the resolution or by other matrix influences than quenching  OH-bending reduces tunneling splitting  Evaluation of theoretical models  Starting points for hi-res. spectroscopy * C. Duan, D. Luckhaus, Chem. Phys. Lett., 391, 129, 2004 T. N. Wassermann, D. Luckhaus, S. Coussan, M. A. Suhm, Phys. Chem. Chem. Phys. 2006, 8, 2344-2348 (Communication)

19. Tobias N. Wassermann Institute of Physical Chemistry Goettingen 61st Ohio State University Symposium on Molecular Spectroscopy 19 19/06/2006 Proton tunneling estimates for malonaldehyde vibrations T. D. Sewell, Y. Guo, D. L. Thompson, J. Chem. Phys., 103(19), 8557, 1995 V. A. Benderskii, E. V. Vetoshkin, I. S. Irgibaeva, H.-P. Trommsdorff, Russ. Chem. Bull, Int. Ed., 50(7), 1148, 2001 D. Tew, N. C. Handy, S. Carter, S. Irle J. Bowman, Molec. Phys., 102(21-22), 2217, 2004 R. Meyer, T.K. Ha, Molec. Phys., 101(22), 3263, 2003 C. J. Seliskar, R. E. Hoffman, J. Mol. Spectrosc., 96, 146, 1982 C. Duan, D. Luckhaus, Chem. Phys. Lett., 391, 129, 2004 This work

20. Georg-August-Universitaet Goettingen Tobias N. Wassermann Institute of Physical Chemistry Goettingen 19/06/2006 61st Ohio State University Symposium on Molecular Spectroscopy Acknowledgement  Prof. Dr. M. Suhm  Dr. D. Luckhaus  C. Rice  Dr. S. Coussan and his group from Université de Provence, Marseille  Members of the Suhm group  Financial Support: GRK 782 of the DFG (www.pcgg.de)

21. Georg-August-Universitaet Goettingen Tobias N. Wassermann Institute of Physical Chemistry Goettingen 19/06/2006 61st Ohio State University Symposium on Molecular Spectroscopy Thank you for your attention!

22. Georg-August-Universitaet Goettingen Tobias N. Wassermann Institute of Physical Chemistry Goettingen 19/06/2006 61st Ohio State University Symposium on Molecular Spectroscopy Appendix

23. Tobias N. Wassermann Institute of Physical Chemistry Goettingen 61st Ohio State University Symposium on Molecular Spectroscopy 23 19/06/2006 Proton tunneling estimates for malonaldehyde vibrations AcAc C 2v MAAcAc C S

24. Tobias N. Wassermann Institute of Physical Chemistry Goettingen 61st Ohio State University Symposium on Molecular Spectroscopy 24 19/06/2006 Proton tunneling estimates for malonaldehyde vibrations

25. Tobias N. Wassermann Institute of Physical Chemistry Goettingen 61st Ohio State University Symposium on Molecular Spectroscopy 25 19/06/2006 Proton tunneling estimates for malonaldehyde vibrations

26. Tobias N. Wassermann Institute of Physical Chemistry Goettingen 61st Ohio State University Symposium on Molecular Spectroscopy 26 19/06/2006 Proton tunneling estimates for malonaldehyde vibrations

27. Tobias N. Wassermann Institute of Physical Chemistry Goettingen 61st Ohio State University Symposium on Molecular Spectroscopy 27 19/06/2006 Proton tunneling estimates for malonaldehyde vibrations

28. Tobias N. Wassermann Institute of Physical Chemistry Goettingen 61st Ohio State University Symposium on Molecular Spectroscopy 28 19/06/2006 Proton tunneling estimates for malonaldehyde vibrations

29. Tobias N. Wassermann Institute of Physical Chemistry Goettingen 61st Ohio State University Symposium on Molecular Spectroscopy 29 19/06/2006 Proton tunneling estimates for malonaldehyde vibrations