1. Observation of Vortices in Superfluid He Droplets 67 th International Symposium on Molecular Spectroscopy Luis F. Gomez 1, Evgeny Loginov 2, and Andrey F. Vilesov 1 1 Department of Chemistry, University of Southern California, Los Angeles, USA 2 SICPA S.A., Prilly, Switzerland

2. 2 N He ~ 10 4 Small Droplets vs. Larger Droplets... “Photoabsorption of Ag Clusters (N = 6-6 000) in He Droplets…” FD 09, 11:21 am, 1015 McPherson Lab N He ~ 10 7 – 10 10 D He ~ 100–1 000 nm

3. 3 Gomez, Loginov, Sliter, Vilesov, J. Chem. Phys. (2011) He Droplet Sizes I II III

4. Buchenau, Northby, Knuth, Toennies, Winkler, J. Chem. Phys. (1990) 4 67 IIIIII Expansion Isentropes and Regimes of Nozzle Operation at P 0 = 20 bar

5. 5 Surface Deposition of Ag Clusters Grown in He droplets 5.5 – 7 K

6. T 0 = 7 K D droplet = 100 nm 6 0.5 min 2 min32 min 120 min 32 min, no droplets Loginov, Gomez, Vilesov, J. Phys. Chem. A (2011) Ag Clusters Formed in Droplets of 10 7

7. 1000 nm T 0 = 5.5 K, 20 bar D droplet = 1000 nm 7 Ag Clusters from VERY Large 10 10 Droplets Gomez, Loginov, Vilesov, Phys. Rev. Lett. 108, 155302 (2012)

8. 500 nm (B) 20 nm From images: Average length = 540 ± 220 nm N Ag ~ 10 6 Gomez, Loginov, Vilesov, Phys. Rev. Lett. 108, 155302 (2012) 8 A Typical Tracked Ag Cluster

9. 9 without guided growthin a vortex Cluster Growth in He Droplets

10. as a whole and with a vortex 10 Rotational Motion in He Droplets

11. Kinetic energy of displaced superfluid: E M = ½ ρ He ·V M ·v X 2 r vXvX Dalfovo, Mayol, Pi, Barranco, PRL 85 (2000) 1028 11 Interaction of Vortex and Impurity

12. L.F. Gomez, E. Loginov, A.F. Vilesov, Phys. Rev. Lett. 108, 155302 (2012) 12 Trapping Vortices in He Droplets

13. Large He droplets contain vortices. Vortices serve as aggregation centers to give elongated, tracked clusters. In the future, we will extend spectroscopic studies to see how vortices project onto the spectra of the embedded clusters. Conclusions