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

Time of flight measurement of femtosecond ablation of graphite

Motivation: mechanism(s) in femtosecond laser ablation ?

TOFProducts ONLY

from surface ?

TOF Products from

surface + fragmentation ?

Thermal (equilibrium)

or/and

coulomb explosion (non equilibrium)?

Nd:YLF1 kHz = 527 nm

Up to 25 mJ

RegenerativeAmplifier

1 kHz100 fs

Up to 2 mJ

Ti:Sapphire,82 MHz, 800 nm,

100 fs, 600 mW

Ar+ laserAll lines

6 W

Argon gas flow

Transfer arm

PMTDifferentialpumpingchamber

STMchamber

Ablationchamber

Time-of-flightspectrometer

HHGchamber

LAYOUT PUMP-PROBE

Principle of TOF spectrometer

m

mU0

eV Ions desorbed from surface: if D >> s

s D

Source/extraction Drift region Detector

E2 = 0 E1 = V/sV

QuickTime™ and aTIFF (LZW) decompressor

are needed to see this picture.QuickTime™ and a

TIFF (LZW) decompressorare needed to see this picture.

Model used for ablation process

QuickTime™ and aTIFF (LZW) decompressor

are needed to see this picture.

C1

C7

C3

C2

Ratio ≈ 11

pulse= 100 fs

Epulse= 200 J

Usample= 500 V

QuickTime™ and aTIFF (LZW) decompressor

are needed to see this picture.

C2

C3

C4

pulse= 100 fs

Epulse= 10.5 J

Usample= 405 V

KE distribution spread as a function of the voltage

QuickTime™ and aTIFF (LZW) decompressor

are needed to see this picture.

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