1. Institute of Experimental Physics 1 Wolfgang E. Ernst ESR Spectra of Alkali Metal Atoms on Helium Nanodroplets: a Theoretical Model for the Prediction of Helium Induced HFS Shifts Andreas W. Hauser, Michael Filatov, and Wolfgang E. Ernst 68th Int. Symp. on Molecular Spectroscopy, Columbus, Ohio June 17-21, 2013 Institute of Experimental Physics Research funded by Fonds zur Förderung der wissenschaftlichen Forschung & EU regional development fund (ERDF) Currently at UC Berkeley Mulliken Center Univ. Bonn

2. Institute of Experimental Physics 2 Wolfgang E. Ernst 68th Int. Symp. on Molecular Spectroscopy, Columbus, Ohio June 17-21, 2013 The hyperfine structure of alkali metal atoms Special case: single electron in s-orbital Li Na KRb

3. Institute of Experimental Physics 3 Wolfgang E. Ernst 68th Int. Symp. on Molecular Spectroscopy, Columbus, Ohio June 17-21, 2013 ESR shifts induced by He-droplets Free Rb Rb on He 8000 E = Experiment by M. Koch, G. Auböck, C. Callegari and W.E. Ernst, PRL 103, 035302 (2009) HFS constant

4. Institute of Experimental Physics 4 Wolfgang E. Ernst 68th Int. Symp. on Molecular Spectroscopy, Columbus, Ohio June 17-21, 2013 HFS shifts induced by He-droplets ?

5. Institute of Experimental Physics 5 Wolfgang E. Ernst 68th Int. Symp. on Molecular Spectroscopy, Columbus, Ohio June 17-21, 2013 The strategy …. 1) Basis set selection for atomic HFS (Ak=Li, Na, K, Rb) 2) Calculation of the 2 Σ 1/2 ground states of Ak-He 3) A DFT simulation of Ak attached to He-droplets 4) Combine 2 and 3 to predict HFS of Ak on droplets

6. Institute of Experimental Physics 6 Wolfgang E. Ernst 68th Int. Symp. on Molecular Spectroscopy, Columbus, Ohio June 17-21, 2013 1) Choice of basis set

7. Institute of Experimental Physics 7 Wolfgang E. Ernst 68th Int. Symp. on Molecular Spectroscopy, Columbus, Ohio June 17-21, 2013 1) Choice of basis set Li: Na: K: Rb: * Young, D. : Computational Chemistry. New York : John Wiley and Sons, 2001 * Note the huge contraction

8. Institute of Experimental Physics 8 Wolfgang E. Ernst 68th Int. Symp. on Molecular Spectroscopy, Columbus, Ohio June 17-21, 2013 1) Choice of basis set Isotropic hfs constants [MHz] in the atomic ground state:

9. Institute of Experimental Physics 9 Wolfgang E. Ernst 68th Int. Symp. on Molecular Spectroscopy, Columbus, Ohio June 17-21, 2013 2) HFS splitting in Ak-He diatomic PES of the ground stateRelative HFS shift For the diatomic systems: use the normalized elimination of the small component (NESC) method (Dyall, Filatov & Co., 1997-2011) in connection with the coupled-cluster singles and doubles (CCSD) formalism.

10. Institute of Experimental Physics 10 Wolfgang E. Ernst 68th Int. Symp. on Molecular Spectroscopy, Columbus, Ohio June 17-21, 2013 3) DFT calculations Rb

11. Institute of Experimental Physics 11 Wolfgang E. Ernst 68th Int. Symp. on Molecular Spectroscopy, Columbus, Ohio June 17-21, 2013 3) DFT calculations He-droplet with N = 500 * figure from J. Poms, A.W. Hauser and W.E. Ernst, PhysChemChemPhys 14, 1558 (2012)

12. Institute of Experimental Physics 12 Wolfgang E. Ernst 68th Int. Symp. on Molecular Spectroscopy, Columbus, Ohio June 17-21, 2013 3) DFT calculations: Energy

13. Institute of Experimental Physics 13 Wolfgang E. Ernst 68th Int. Symp. on Molecular Spectroscopy, Columbus, Ohio June 17-21, 2013 3) DFT calculations: Density He-droplet with N = 500 * figure from J. Poms, A.W. Hauser and W.E. Ernst, PhysChemChemPhys 14, 1558 (2012)

14. Institute of Experimental Physics 14 Wolfgang E. Ernst 68th Int. Symp. on Molecular Spectroscopy, Columbus, Ohio June 17-21, 2013 Relevant area Ak-He N with: blue  N = 50, red  N = 100, green  N = 200, magenta  N = 500

15. Institute of Experimental Physics 15 Wolfgang E. Ernst 68th Int. Symp. on Molecular Spectroscopy, Columbus, Ohio June 17-21, 2013 4) Putting things together...

16. Institute of Experimental Physics 16 Wolfgang E. Ernst 68th Int. Symp. on Molecular Spectroscopy, Columbus, Ohio June 17-21, 2013 4) Putting things together... + From He-DFT code From NESC/CCSD calculation with r 0 denoting the position of alkali-metal atom.

17. Institute of Experimental Physics 17 Wolfgang E. Ernst 68th Int. Symp. on Molecular Spectroscopy, Columbus, Ohio June 17-21, 2013 4) Putting things together... See also A. W. Hauser, T. Gruber, M. Filatov, and W. E. Ernst, ChemPhysChem 14, 716 (2013)

18. Institute of Experimental Physics 18 Wolfgang E. Ernst 68th Int. Symp. on Molecular Spectroscopy, Columbus, Ohio June 17-21, 2013 Summary Helium droplet environment affects ESR spectra of alkali-metal atoms Effect is mainly related to isotropic HFS constant → s-orbital compression? 'Dimer' picture: Generalization from Ak-He diatomic to Ak on He droplet Experimental data for Rb can be reproduced; Li, Na, and K predicted

19. Institute of Experimental Physics 19 Wolfgang E. Ernst 68th Int. Symp. on Molecular Spectroscopy, Columbus, Ohio June 17-21, 2013 Acknowledgments to: Austrian Science Fund grant P19759-N20 European Commission ERDF programme ERDF

20. Institute of Experimental Physics 20 Wolfgang E. Ernst 68th Int. Symp. on Molecular Spectroscopy, Columbus, Ohio June 17-21, 2013 Graz, 18 th - 22 nd August 2014 XXIInd International Symposium on the Jahn-Teller Effect Institute of Experimental Physics

21. 21 Wolfgang E. Ernst 68th Int. Symp. on Molecular Spectroscopy, Columbus, Ohio June 17-21, 2013 Thank you for your attention !

22. Institute of Experimental Physics 22 Wolfgang E. Ernst 68th Int. Symp. on Molecular Spectroscopy, Columbus, Ohio June 17-21, 2013 Markus Koch, Gerald Auböck, Carlo Callegari, and Wolfgang E. Ernst, Coherent Spin Manipulation and ESR on Superfluid Helium Nanodroplets, Phys. Rev. Lett. 103, 035302-1-4 (2009), also July 27, 2009 issue of Virtual Journal of Nanoscale Science & Technology, http://www.vjnano.org.http://www.vjnano.org Markus Koch, Johannes Lanzersdorfer, Carlo Callegari, John S. Muenter, and Wolfgang E. Ernst, Molecular beam magnetic resonance in doped helium nanodroplets: A setup for optically-detected ESR/NMR in the presence of unresolved Zeeman splittings, J. Phys. Chem. A 113, 13347-13356 (2009) (Festschrift in honor of Robert W. Field). Markus Koch, Carlo Callegari, and Wolfgang E. Ernst, Alkali-metal electron spin density shift induced by a helium nanodroplet, Mol. Phys. 108 (7), 1005-1011 (2010) (invited article in honour of Richard N. Zare). Alexander Volk, Johannes Poms, Markus Koch, and Wolfgang E. Ernst, 87 Rb Electron Spin Resonance on Helium Nanodroplets: the Influence of Optical Pumping, J. Phys. Chem. A 115, 7065-70 (2011) (Festschrift in honor of J. Peter Toennies). References: ESR experiments:

23. Institute of Experimental Physics 23 Wolfgang E. Ernst 68th Int. Symp. on Molecular Spectroscopy, Columbus, Ohio June 17-21, 2013 References: DFT code:

24. Institute of Experimental Physics 24 Wolfgang E. Ernst 68th Int. Symp. on Molecular Spectroscopy, Columbus, Ohio June 17-21, 2013 References: Relativistic theory:

25. Institute of Experimental Physics 25 Wolfgang E. Ernst 68th Int. Symp. on Molecular Spectroscopy, Columbus, Ohio June 17-21, 2013 References: Basis sets:

26. Institute of Experimental Physics 26 Wolfgang E. Ernst 68th Int. Symp. on Molecular Spectroscopy, Columbus, Ohio June 17-21, 2013 References: Method used:

27. Institute of Experimental Physics 27 Wolfgang E. Ernst 68th Int. Symp. on Molecular Spectroscopy, Columbus, Ohio June 17-21, 2013