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Spectra, Structures, and Dynamics of Weakly Bound Clusters from Dimers to Nonamers

Spectra, Structures, and Dynamics of Weakly Bound Clusters from Dimers to Nonamers. Wolfgang Jäger Department of Chemistry, University of Alberta. Potential Energy Curves for H-Cl and Kr-Xe. Significance of van der Waals Interactions. Significance, continued ….

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Spectra, Structures, and Dynamics of Weakly Bound Clusters from Dimers to Nonamers

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  1. Spectra, Structures, and Dynamics of Weakly Bound Clusters from Dimers to Nonamers Wolfgang Jäger Department of Chemistry, University of Alberta

  2. Potential Energy Curves for H-Cl and Kr-Xe

  3. Significance of van der Waals Interactions

  4. Significance, continued …

  5. Fourier Transform Microwave Spectrometer Frequency range: 4 – 26 GHz (ca. 0.1 – 1 cm-1)

  6. Fourier Transform Microwave Spectrometer microwave cavity nozzle

  7. Outline for Remainder of Talk • large amplitude motions in van der Waals complexes • three-body effects in ternary and quaternary clusters • successive micro-solvation of molecules with helium atoms

  8. Ne-Ethylene in its Principal Inertial Axis System

  9. Energy Level Diagram of Ne-trans-C2D2H2(Out-of-Plane Motion)

  10. Energy Level Diagram of Ne-trans-C2D2H2(In-Plane Motion)

  11. RGN-NH3 Complexes Ne, Ar,a Kr NH3 Ne, Ar NH3 Ne, Ar NH3 15NH315NH315NH3 ND3 ND3 ND3 ND2H ND2H ND2H NDH2 NDH2 NDH2 a Ar-NH3, Ar-15NH3 by D. D. Nelson Jr. et al., JCP85, 512 (1986); E. Zwart et al., JCP95, 793 (1991); and many others.

  12. J=4-3 Transitions of Deuterated Ar3-Ammonia

  13. Ammonia internal rotation in RGN-NH3 clusters 14N nuclear quadrupole coupling constants in MHz 14N nuclear quadrupole coupling constant in free ammonia: P=-4.0898 MHz M. D. Marshall and J. S. Muenter, JMS85, 322 (1981).

  14. Three-Body Interactions

  15. Three-body interactions crystal structures of solid rare gases face-centered cubic (observed) hexagonal close-packed (predicted using pairwise additivity)

  16. Pure Rare Gas Clusters Ne3Ar Ne2Ar NeAr Ne2Ar2 NeAr2 NeAr3

  17. Survey Scan with Ne/Ar Sample Gas Mixture

  18. Transitions JKaKc = 202-101 of Ne2Ar

  19. Rotational Energy Level Diagrams Ne2Ar NeAr2

  20. Comparison with Theoretical Calculations References: 1. Ernesti & Hutson, JCP103, 3386 (1995). 2. Aziz & Slaman, Chem. Phys.130, 187 (1989). Ne-Ne PES ~ viscosity data & high energy total cross sections 3. Barrow & Aziz, JCP89, 6189 (1988). Ne-Ar PES ~ low energy total cross section data & low temperature second virial coefficients & room temperature diffusion coefficients & high energy total cross sections modified (scaled re) to fit MW data [JCP 102, 1181 (1995)].

  21. Helium – Molecule Complexes very weak interactions • high zero point energy • spectra sample significant portion of PES • attractive systems for ab initio calculations relevant wrt spectroscopy of doped helium droplets possibility to measure Hen-molecule systems? S. Grebenev, J. P. Toennies, and A. F. Vilesov, Science279, 2083 (1998).

  22. Helium Nanodroplet Isolation Spectroscopy (Background) Grebenev, Toennies, Vilesov, Science279, 2083 (1998).

  23. Helium Nanodroplet Isolation Spectroscopy (more Background) Grebenev, Toennies, Vilesov, Science279, 2083 (1998).

  24. He-OCS in its Principal Inertial Axes System

  25. Measured Rotational Transitions of He-OCS

  26. He2-OCS in its Principal Inertial Axes System

  27. JKaKc=101-000 Transitions of He2-OCS

  28. Multidimensional Assignment Procedure a) infrared predictions b) sample conditions (pressure, temperature) c) double resonance experiments d) consistency of isotopic data e) spectral fits

  29. Effect of Nozzle Cooling on Cluster Formation He6-OCS, J=3-2 at 11176.83 MHz, 0.01% OCS in He at 20.4 atm 100 averaging cycles nozzle at room temperature S/N ~ 2 nozzle at dry ice temperature (-78.5 C) S/N ~ 40

  30. Double Resonance Spectrometer

  31. Double Resonance Spectrometer (Schematics)

  32. Double Resonance Experiments on He6-OCS pump power (continuous) off -3 dBm 3 dBm signal: J-3-2, 11176.83 MHz pump: J=2-1, 7588.75 MHz 20 averaging cycles

  33. Vibrational Frequency Shifts of HeN-OCS Clusters experimental values Tang et al., Science, accepted. values from Whaley and co-workers, JCP115, 10225 (2001).

  34. Moment-of-Inertia Shifts of Isotopomers

  35. Proposed Structure of He8-OCS

  36. Spectroscopic Constants of HeN-OCS Clusters

  37. Rotational Constants of HeN-OCS Clusters

  38. Potential Energy Surface of He-N2O CCSD(T) level of theory, aug-cc-pVDZ basis set

  39. Bound State Calculations

  40. Wavefunction of Ground State

  41. Wavefunctions of 1st and 2nd Excited States

  42. J=1-0 Spectrum of He5-N2O

  43. He6-N2O in its Principal Inertial Axes System

  44. Acknowledgements Dr. Yunjie Xu (H31) Dr. Aiko Huckauf Dean Court Dr. Yaqian Liu (H19) Dr. Jennifer van Wijngaarden (H15) Dr. Silas Ngari Kai Brendel (H30) Hans Osthoff Wendy Topic Tobias Klemmer James Song Mike Gerry Bob McKellar PN Roy NSERC ASRA CIPI

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