M ax-B orn-In stitu t Femtosecond Laser Spectroscopy of C 60 Nieuwegein, The Netherlands August 21, 2001 Eleanor Campbell, Göteborg University & Chalmers, Sweden R.D. Levine, Fritz Haber Center, Hebrew University yle, K. Hoffmann, R. Stoian, C.P.Schulz & I.V. Her
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Femtosecond Laser Spectroscopy of C 60 Nieuwegein, The Netherlands August 21, 2001 Eleanor Campbell, Göteborg University & Chalmers, Sweden R.D. Levine,
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M ax-Born-In stitut
Femtosecond Laser Spectroscopy of C60
Nieuwegein, The Netherlands August 21, 2001
Eleanor Campbell, Göteborg University & Chalmers, SwedenR.D. Levine, Fritz Haber Center, Hebrew University
M. Boyle, K. Hoffmann, R. Stoian, C.P.Schulz & I.V. Hertel
Max-Born-Institut, Mark Boyle 21.08.01 2
Outline
1.) Observed Rydberg Structure in photo-electron spectra
•What do we learn about the Rydberg states from photoelectron spectroscopy?
•Excitation and ionization process
2.) Femtosecond Pulse Shaping on C60
•interested in impulsively exciting vibrational modes
Max-Born-Institut, Mark Boyle 21.08.01 3
Experimental TOF Apparatus
Electron TOF
e- Ion+
C60-Oven
Double µ-Metal Shielding
Wiley-McLaren Reflectron TOF
x
y
z
Max-Born-Institut, Mark Boyle 21.08.01 4
Experimental Variable Parameters
•Intensity - 1011-1013 W/cm2
•Wavelength- 800nm, 400nm, 660nm
•Bandwidth Limited Pulse Duration
•Chirp
•Polarization
Max-Born-Institut, Mark Boyle 21.08.01 5
Intensity Dependence of Photoelectron Spectra= 800 nm, = 1.5 ps
elec
tron
yie
ld /
lo
g u
nits
1.5x1012 W/cm2
e - -energy / eV
100
101
102
103
104
105
106
100
101
102
103
104
105
100
101
102
103
104
05 10 15 20
100
101
102
103
104
1 2
0.5
30
60
90
10
20
30
1
2
3
0 0,5 1,5
1 elec
tron
yie
ld *
104 /
arb.
uni
ts
1.1x1012 W/cm2
2.2x1012 W/cm2
3.6x1012 W/cm2
0
0
0
0
Max-Born-Institut, Mark Boyle 21.08.01 6
Wavelength Dependence of Binding Energy
0 1 2 3
-0,2
0,0
0,2
0,4
0,6
0,8
1,0
-0,15
Binding Energy [eV]
No
rmal
ized
Sig
nal
800nm , 1.5 ps 660nm, 120 fs 400nm, 2.1 ps
***assuming 1-photon ionization
IP
Max-Born-Institut, Mark Boyle 21.08.01 7
Bandwidth Limited Pulse Duration Electron Spectra Comparison E*=0.441
0,0 0,5 1,0 1,5 2,0
E ~ 85meV ~ 30fs
Energy[eV]
E ~10meV ~180 fs
E~20meV ~100 fs
Rydberg spectra seen for pulsedurations as short as 25 fs