1. High Resolution Microwave Spectra of He N – and (H 2 ) N – Linear Molecule Clusters Wolfgang Jäger Department of Chemistry, University of Alberta, Edmonton, AB Canada Collaborations: Yunjie Xu, UofA Bob McKellar, NRC PN Roy, Nick Blinov, UofA

2. (H 2 ) N – Molecule Clusters on this Meeting MH15: H 2 – C 5 H 5 N Chakree Tanjaroon TE02: (H 2 ) N – N 2 O, N up to 6 Jen Landry TE03: (H 2 ) N – OCS, N up to 7 Julie Michaud

3. Wolfgang Jäger Department of Chemistry, University of Alberta, Edmonton, AB Canada Collaborations: Yunjie Xu, UofA Bob McKellar, NRC PN Roy, Nick Blinov, UofA High Resolution Microwave Spectra of He N – Linear Molecule Clusters

4. Impetus for He N -Molecule Studies He – OCS, He – HF, etc. studies by Higgins and Klemperer. SF 6, OCS Helium nanodroplet studies by the Scoles/Lehmann and Toennies/Vilesov groups. 50 th OSU Symposium, Outstanding Challenges for Molecular Spectroscopy (compiled and distilled by Kevin Lehmann) V. Towards a true Microscopic Theory of Condensed Matter … e) Improvements in experiments and theory of the size dependence of molecular properties to better understand the transition from an isolated molecule – small cluster – condensed phase.

5. A Case in Point: Superfluidity 4 He becomes superfluid below the λ-point (2.17 K). Frictionless flow, irrotationality, quantized vorticity, fountain effect … Andronikashvili experiment ‘Drag’ from normal fluid component causes increase of moment-of-inertia of disk stack. Confirmation of two–fluid model.

6. The Microscopic Andronikashvili Experiment Grebenev, Toennies, Vilesov, Science 279, 2083 (1998). Pure 4 He droplet Pure 3 He droplet 4 He droplet with 20 3 He 4 He droplet with 40 3 He 4 He droplet with 60 3 He 4 He droplet with 1000 3 He

7. Alberta: Rotational (microwave) spectra of He N -molecule clusters. Instrument: FTMW Spectrometer, 2.5 - 11 GHz. Ottawa: Ro-vibrational (infrared) spectra of He N -molecule clusters. Instrument: Rapid Scan mid-IR Diode Laser spectrometer. Instrument and Technique

8. Multidimensional Assignment Procedure infrared predictions sample conditions (pressure, temperature) double resonance experiments consistency of isotopic data spectral fits

9. He N -OCS He N – Molecule Clusters

10. Effect of Nozzle Cooling on Cluster Formation He 6 -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

11. Double Resonance Spectrometer

13. Double Resonance Experiments on He 6 -OCS signal: J-3-2, 11176.83 MHz pump: J=2-1, 7588.75 MHz 20 averaging cycles pump power (continuous) off -3 dBm 3 dBm Double resonance experiments also with the ‘decoherence technique’. Brendel, Mäder, OSU Symposium 2004, paper TA05.

14. Vibrational Frequency Shifts of He N -OCS Clusters experimental values, Tang et al., Science 297, 2030 (2002). values from Whaley and co-workers, JCP 115, 10225 (2001). Paesani, Whaley, JCP 121, 4180 (2004).

15. Vibrational Frequency Shifts of He N -OCS Clusters experimental values, Tang et al., Science 297, 2030 (2002). values from Whaley and co-workers, JCP 115, 10225 (2001).

16. Moment-of-Inertia Shifts of Isotopomers )I / amuD 2 32.2 48.8 35.7 37.4 32.1

17. Proposed Structure of He 8 -OCS

18. Helium density in He 8 -OCS P. N. Roy, N. Blinov, private communication.

19. Spectroscopic Constants of He N -OCS Clusters MoleculeB / MHzD / MHz Free OCS6081.591.31x10 -5 He-OCS13208.57 5504.18 4582.80 3661.42 0.950 He 2 -OCS 5803.39 4546.34 3782.81 3019.28 --- He 3 -OCS 3104.575.11 He 4 -OCS2591.950.881 He 5 -OCS2225.150.234 He 6 -OCS1910.492.60 He 7 -OCS1682.981.29 He 8 -OCS1447.732.00 OCS in 4 He droplet (N~3,000) 2194.5(90)11.4(3)

20. Rotational Constant vs.Number of He Atoms

21. Quantum Monte Carlo Calculations. N. Blinov, X. Song, P. N. Roy, JCP 120, 5916 (2004). S. Moroni et al., Phys. Rev. Lett. 90, 143401 (2003).

22. Helium Density Profiles in He N -OCS N. Blinov, X. Song, P. N. Roy, JCP 120, 5916 (2004). N=5 N=7 N=9 N=6 N=8 N=10

23. He N -N 2 O He N – Molecule Clusters

24. He 6 -N 2 O in its Principal Inertial Axes System

25. J=1-0 Rotational Transition Intensity Frequency / MHz He 7 - 14 N 15 NO He 5 - 14 N 15 NO Intensity He 12 - 14 N 15 NO 6792.0 6793.5 5471.5 5473.0 6194.5 6195.5

26. Rotational Constant vs.Number of He Atoms S. Moroni, N. Blinov, P. N. Roy, J. Chem. Phys 121, 3577 (2004). Helium droplet value Nauta, Miller, JCP 115, 10254 (2001). Xu, Jäger, Tang, McKellar, Phys. Rev. Lett. 91, 163401 (2003). Xu, Jäger, Blinov, Roy, J. Chem. Phys. 124, 081101 (2006).

27. Helium Density Distributions in He N -N 2 O N=5 N=9 N=14 N=6 N=10 N=15

28. Back to He N -OCS He N – Molecule Clusters

29. Infrared Spectra of He N -OCS Clusters Wavenumber / cm -1 Bob McKellar, paper FD01

30. Nanodroplet value ν J=1-0 ≈ 2B J=1-0 MW Transitions of He N -OCS Clusters ν J=1-0 ≈ 2B 400 kHz

31. J=1-0 MW Transitions of He N -OCS Clusters Rudi Lehnig, RD05 7000

32. J=1-0 MW Transitions of He N -OCS Clusters Rudi Lehnig, RD05 7000

33. Rotational Constant B as Function of Cluster Size

35. Aufbau of a Helium Solvation Shell Structure

36. Acknowledgements Dr. Dominik Bremm Dr. Rudi Lehnig (RD05) Dr. Chakree Tanjaroon (MH15) Jen Landry (TE02) Julie Michaud (TE03) Wendy Topic Qing Wen (TE05) NSERC, CFI, ASRIP, University of Alberta, CRC