(Downloads - 0)
For more info about our services contact : help@bestpfe.com
Table of contents
Introduction
I Matter under extreme conditions
I.1 Ultrafast lattice dynamics and solid-liquid phase transitions
I.1.1 Phenomenological description
a) Energy absorption, heating and equilibration
b) Thermal and non-thermal phase transitions
I.1.2 Theory: modelling and limitations
a) Energy absorption
b) The two-temperature model
c) Hydrodynamic simulations
d) Molecular dynamic simulations
e) Quantum molecular dynamic simulations
I.2 Experimental state of the art
I.2.1 Time-resolved x-ray absorption spectroscopy
I.2.2 Time-resolved optical measurements
I.2.3 Time-resolved x-ray and electron diffraction
I.3 Time-resolved photoelectron spectroscopy
I.3.1 Principle
I.3.2 Interpretation
I.3.3 Characteristics
a) Probing depth
b) Photoionization cross section
I.3.4 Photoelectron spectroscopy in the context of lattice heating
a) State of the art
b) Experimental scheme
c) Challenges
II Experimental method
II.1 Infrared femtosecond laser source: the Aurore facility
II.2 XUV source: a 100 eV beamline based on high order harmonic generation
II.2.1 Theoretical principles of high order harmonic generation .
a) Microscopic aspects of the HHG
b) Macroscopic aspects of the HHG
II.2.2 XUV beamline design and characterization
a) HH generation stage
b) HH selection and focusing
c) HH characterization
d) Performance
II.3 Pump/Probe experiment
II.3.1 Pump beamline focusing and fluence calculations
II.3.2 Pump pulse temporal characterization
II.3.3 Pump/Probe synchronization and spatial overlap
II.4 Interaction chamber for photoelectron spectroscopy
II.4.1 Vacuum requirements
II.4.2 Photoelectron spectrometer
II.4.3 Sample manipulation, cleaning and XPS characterization .
II.4.4 Valence band photoelectron spectrum measurements
III Space-charge effect study
III.1 Introduction and motivation
III.2 Experimental Results
III.3 Numerical models for the pump-probe space-charge effect
III.3.1 Pump initial spectrum calculations: the jellium-Volkov approximation
III.3.2 Simulated Matter Irradiated by Light at Extreme Intensities (SMILEI) simulations
III.3.3 A Space-Charge Tracking Algorithm (ASTRA) simulations
III.4 Numerical simulations: results and comparison to experimental measurements
III.4.1 Jellium-Volkov Pump initial emission
III.4.2 SMILEI laser-plasma simulations
III.4.3 Pump/probe Jellium-Volkov-ASTRA simulations
a) Standard simulation
b) Comparison of the (x, y, z) distribution with an (x, y, t) cathode emission distribution
c) Number of electrons as the key parameter
d) Transversal size of the electron bunches
e) Angular distribution
f) Sorting of particles
g) Delay on the mirror charges
h) Analyzing shift and broadening
III.4.4 Pump/probe SMILEI-ASTRA simulations
a) Varying the low temperature (TLow)
b) Varying the high T temperature (THigh)
c) Varying proportion between THigh and TLow populations
d) Varying the cutoff of the initial pump spectrum
III.4.5 Pump/probe experimental pump-ASTRA simulations
a) Gaussian fits from the experimental spectrum .
b) Experimental spectrum
III.4.6 Summary and discussion of the pump induced space-charge effect study
III.5 Experimental reduction of the pump-probe space-charge effect
IV Ultrafast lattice dynamics studied by photoelectron spectroscopy
IV.1 Sample
IV.1.1 Selection of the samples
IV.1.2 Sample preparation and characterization
IV.2 Tr-PES experimental measurements
IV.2.1 Acquisition conditions
IV.2.2 Data analysis procedure
IV.2.3 Measurements of the different pump fluences
IV.3 Interpretation
IV.3.1 Disentangling the space-charge effect
IV.3.2 Interpretation of the photoelectron spectrum
a) ABINIT density functional theory calculations of the density
of occupied states
b) Hydrodynamic calculations and the two temperature model:
The ESTHER Code
IV.4 Summary and conclusion
Conclusions
Context and contributions
Bibliography
