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

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Nanoscale Physics Research Laboratory

School of Physics and Astronomy

The University of Birmingham

United Kingdom

Time of flight measurement of femtosecond ablation of graphite

Christophe Huchon

Attosecond meeting, 7 december 2005, Rutherford Appleton Laboratory


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)?


LAYOUT PUMP-PROBE

Nd:YLF

1 kHz l = 527 nm

Up to 25 mJ

Ti:Sapphire,

82 MHz,

800 nm,

100 fs, 600 mW

Transfer arm

Regenerative

Amplifier

1 kHz

100 fs

Up to 2 mJ

STM

chamber

Time-of-flight

spectrometer

Ablation

chamber

Ar+ laser

All lines

6 W

PMT

Differential

pumping

chamber

HHG

chamber

Argon gas flow


Source/extraction

Drift region

Detector

E1 = V/s

E2 = 0

V

s

D

Principle of TOF spectrometer

 Ions desorbed from surface: if D >> s


Model used for ablation process


pulse= 100 fs

Epulse= 200 J

Usample= 500 V

Ratio ≈ 11


pulse= 100 fs

Epulse= 10.5 J

Usample= 405 V


KE distribution spread as a function of the voltage

pulse= 100 fs

Epulse= 10.5 J


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


Acknowlegdement

  • Andrey Kaplan

  • Miklos Lenner

  • Quanmin Guo

  • Richard Palmer


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