1. Photoelectron Spectroscopy of Doped Helium Nanodroplets
Evgeniy Loginov
Marcel Drabbels
Talk MG10
65th International Symposium on Molecular Spectroscopy
Columbus, Ohio
June 21, 2010

2. Experimental Setup

3. Photoionization Scheme
Aniline Gas Phase
Photoelectron Image
Ionization Scheme e- S0 S1 IP
ħω1
Photoelectron Spectrum
Probability

4. Photoionization of Doped DropletsÅ Å
Loginov E.,Rossi D., Drabbels M.: PRL (2005)

5. The Shape of Photoelectron PeakÅ
Field strength 30 V/cm
τ ≈ 100 ns
n ≈ 50
re ≈ 250 nm

6. Shift of Ionization Potential
1/R - prefactor values:
experiment: ± 350 cm-1/Å
theory: cm-1/Å
IP∞ shifts:
experiment: -904 ± 3 cm-1
theory: -993 cm-1
Loginov E.,Rossi D., Drabbels M.: PRL (2005)

7. Two-color Photoionization

8. Relaxation of photoelectron kinetic energyÅ
[Å]

9. Two-color Photoionization 2
[Å]

10. Modeling the Relaxation of Kinetic Energy:

11. Photoionization of Na-HeN
Field strength 5 V/cm
τ ≈ 1 µs
n ≈ 100
re ≈ 500 nm

12. Droplet Size Effects in Photoionization of Na-HeN

13. Conclusion Photoelectrons do escape from the helium droplet
Ionization threshold is red-shifted and broadened compared to the gas phase. The shift can be explained within simple polarizable continuum model.
The evidence of photoelectron kinetic energy relaxation is obtained. Simple modeling showed that the elastic scattering of photoelectrons on helium atoms cannot explain it.
Photoionization of surface-doped helium droplets shows red-shift in the ionization potential. Long living Rydberg states with n≈100 of doped helium droplets have been detected.

14. Acknowledgements MER, Dr. Marcel Drabbels Professor Tom Rizzo
MER, Dr. Oleg Boiarkine
Dr. Andreas Braun
Past and present members of LCPM group