1. Time of flight measurement of femtosecond ablation of graphite
Christophe Huchon
Nanoscale Physics Research Laboratory
School of Physics and Astronomy
The University of Birmingham
United Kingdom
Attosecond meeting, 7 december 2005, Rutherford Appleton Laboratory

2. Motivation: mechanism(s) in femtosecond laser ablation ?
TOF
Products ONLY
from surface ?
TOF
Products from
surface + fragmentation ?
Thermal (equilibrium)
or/and
coulomb explosion (non equilibrium)?

3. LAYOUT PUMP-PROBE Nd:YLF 1 kHz l = 527 nm Up to 25 mJ Ti:Sapphire,
Regenerative
Amplifier
1 kHz
100 fs
Up to 2 mJ
Ti:Sapphire,
82 MHz,
800 nm,
100 fs, 600 mW
Ar+ laser
All lines
6 W
Argon gas flow
Transfer arm
PMT
Differential
pumping
chamber
STM
Ablation
Time-of-flight
spectrometer
HHG
LAYOUT PUMP-PROBE

4. Principle of TOF spectrometerD
Source/extraction
Drift region
Detector
E2 = 0
E1 = V/s V
 Ions desorbed from surface: if D >> s

5. Model used for ablation process

6. pulse= 100 fs
Epulse= 200 J
Usample= 500 V
Ratio ≈ 11

7. pulse= 100 fs
Epulse= 10.5 J
Usample= 405 V

8. KE distribution spread as a function of the voltage
pulse= 100 fs
Epulse= 10.5 J

9. Summary
fragmentation process involved in the ablation of the graphite with femtosecond laser pulse.
need to find what is the rate thermal vaporization / Coulomb explosion  VUV probe
VUV, XUV will allow time-resolved photoelectron emission

10. Acknowlegdement
Andrey Kaplan
Miklos Lenner
Quanmin Guo
Richard Palmer