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[TITLE WITH CAPITAL LETTERS] - Aarhus Universitet

AARHUS

UNIVERSITET OCTOBER 31, 2012

PHOTOELECTRONS FROM LASER

ALIGNED MOLECULES

LAUGE CHRISTENSEN

PH.D. STUDENT

UNI VERSITET


AARHUS

UNIVERSITET

OUTLINE

› Femtolab

› Laser Alignment of Molecules.

› Molecular Frame Photoelectrons.

› FEL Experiments

› X-ray induced electron diffraction from laser aligned molecules.

PHOTOELECTRONS FROM LASER ALIGNED MOLECULES

LAUGE CHRISTENSEN

OCTOBER 31, 2012

2


AARHUS

UNIVERSITET

LASER ALIGNMENT OF MOLECULES

› Overlap molecular frame with laboratory frame.

› Atoms : V stark = − 1 4

⋅ α ⋅ ε2

PHOTOELECTRONS FROM LASER ALIGNED MOLECULES

LAUGE CHRISTENSEN

OCTOBER 31, 2012

3


AARHUS

UNIVERSITET

LASER ALIGNMENT OF MOLECULES

› Overlap molecular frame with laboratory frame.

› Atoms : V stark = − 1 4

⋅ α ⋅ ε2

› Molecules: V stark = − 1 4 α ∥ − α ⊥ cos 2 θ ⋅ ε 2 + const.

θ

ε

PHOTOELECTRONS FROM LASER ALIGNED MOLECULES

LAUGE CHRISTENSEN

OCTOBER 31, 2012

4


AARHUS

UNIVERSITET

MOLECULAR FRAME PHOTOELECTRONS

› Alignment Laser:

› 10 ns, 1064 nm,

elliptical polarization.

› Probe Laser:

› 30 fs, 800 nm,

circular polarization.

› Detection:

› Velocity Map Imaging.

J. Maurer, D. Dimitrovski, L. Christensen, L. B. Madsen, and H. Stapelfeldt, PRL 109, 123001 (2012)

PHOTOELECTRONS FROM LASER ALIGNED MOLECULES

LAUGE CHRISTENSEN

OCTOBER 31, 2012

5


AARHUS

UNIVERSITET

MOLECULAR FRAME PHOTOELECTRONS

› Tomographic reconstruction:

› Molecular frame 3D

photoelectron momentum

distribution.

J. Maurer, D. Dimitrovski, L. Christensen, L. B. Madsen, and H. Stapelfeldt, PRL 109, 123001 (2012)

PHOTOELECTRONS FROM LASER ALIGNED MOLECULES

LAUGE CHRISTENSEN

OCTOBER 31, 2012

6


AARHUS

UNIVERSITET

FREE-ELECTRON LASER EXPERIMENTS

PHOTOELECTRONS FROM LASER ALIGNED MOLECULES

LAUGE CHRISTENSEN

OCTOBER 31, 2012

7


AARHUS

UNIVERSITET

FREE-ELECTRON LASER EXPERIMENTS

PHOTOELECTRONS FROM LASER ALIGNED MOLECULES

LAUGE CHRISTENSEN

OCTOBER 31, 2012

8


AARHUS

UNIVERSITET

IONIZATION OF MOLECULES WITH X-RAYS

› Electron detached from inner shell.

› Scatters off the potential from molecular atoms.

› Electron carries structural information.

› Dream:

› Probe of structure in pump-probe experiments.

› Realize molecular movie.

γ

PHOTOELECTRONS FROM LASER ALIGNED MOLECULES

LAUGE CHRISTENSEN

OCTOBER 31, 2012

9


AARHUS

UNIVERSITET

IONIZATION OF MOLECULES WITH X-RAYS

› Laser/FEL overlap:

Holey mirrors.

› Pulsed molecular beam

in He carrier gas.

› Two-sided velocity map

imaging spectrometer.

PHOTOELECTRONS FROM LASER ALIGNED MOLECULES

LAUGE CHRISTENSEN

OCTOBER 31, 2012

10


AARHUS

UNIVERSITET

PHOTOELECTRONS FROM PFAB.

› PFAB ionized by FEL.

› Photon energy ~750 eV.

› 48 eV for Fluorine 1s electrons.

Effect of aligning the molecules:

› Aligned minus unaligned.

› Angular distributions show difference

in the photoline.

PHOTOELECTRONS FROM LASER ALIGNED MOLECULES

LAUGE CHRISTENSEN

OCTOBER 31, 2012

11


AARHUS

UNIVERSITET

PHOTOELECTRONS FROM PFAB.

› EDAC 1 simulations with the

experimentally achieved

alignment.

› Both results show effects

beyond random alignment.

› Good agreement between

experiment and simulation for

lower energies.

1

F. J. Garcia de Abajo et al., Phys. Rev. B. 63, 075404 (2001)

PHOTOELECTRONS FROM LASER ALIGNED MOLECULES

LAUGE CHRISTENSEN

OCTOBER 31, 2012

12


AARHUS

UNIVERSITET

THANK YOU

PHOTOELECTRONS FROM LASER ALIGNED MOLECULES

LAUGE CHRISTENSEN

OCTOBER 31, 2012

13

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