1. Ultrashort Laser Pulses
J. Rauschenberger Diss. 2007 (LMU Munich)
Dye LasersTi:SapphireLasers
Pulse compression
Demtröder
Concepts for Short Pulse Lasers
Demtröder
Concepts for Short Pulse Lasers
Kerr Lens Mode Locking (1991)
Non-linear intensity dependent index of refraction
Only intense radiation is focusedweak radiation is cut by aperture, leading to a shortened pulse
Demtröder
Demtröder
Demtröder
Changing the Laser Pulse Width
Demtröder
Changing the Laser Pulse Width
Demtröder
Self-Phase Modulation and Pulse Compression
Schematic Diagram of a Chirped Pulse Anmplifier (CPA)
Regenerative Amplifier
Femtosecond Laser System
Demtröder
Changing the Laser Pulse Width
Demtröder
Solid State Lasers for Producing Short Laser Pulses
Demtröder
Stretching the Laser Pulse Width
Demtröder
Measuring Short Laser Pulses
Demtröder
Measuring Short Laser Pulses
Attosecond Laser Pulses
Short Laser Pulse
Wavepacket Dynamics
Schematics of Pump-Probe Experiments
NB: instead ionization (detection of electronor ions may also be used)
t= 1.25 ps
Corresponding to 26.7 cm-1
Na2 – NIST Webbook
Coherent Control
Cl(2P) +O(3P)
Cl(2P) +O(1D)
12
Control of Dissociation Dynamics:Use of Shaped Laser Pulses
distance
Ene
rgy
ionization
H. Rabitz: Optimal Control Theory (1988)Experiments: G. Gerber et al. (1998)
Control of Molecular Fragmentation by Shaped Laser Pulses
May 21, 2011
Production of Shaped Light Pulses
grating
SLM
grating
lens
Liquid CrystalSpatial Light Modulator
(SLM)
unshaped pulse
optimized pulse
Coherent Control of Dissociative Ionization: C3H6BrCl
J. Plenge et al., PCCP 13, 8705 (2011)
progress
leading edge
Coherent Control of Dissociative Ionization: C3H6BrCl
optimized pulse
Fitness function:
J. Plenge et al., PCCP 13, 8705 (2011)
Raman Spectroscopy
Demtröder
(d).
Resonance Raman
Coherent Anti-Stokes Raman Scattering (CARS)
Fixed frequency
Tunable frequency
Experimental Setup for CARS
Stimulared Raman Scattering (SRS)
SRS
Surface-Enhanced Raman Scattering (SERS)
Raman Shift Cell
http://www.avesta.ru/pageseng/Raman-shifters-COMPONENTS/40-.htm
Rainbows
Elastic Light Scattering
Diffraction of light at water droplets
Secondary rainbow
primary rainbow
Intensity distribution of angular resolved light scattering
angle
400 nm-radiation is 9.4 times more scattered than 700 nm radiation
Light scattering of gases
Blue color of the skyExtinction coefficient
Phase function
Rayleigh Scattering
Incidence ofthe light
>> d d << d
Result:Negligible wavelength dependence of the scattered light
•
Mie Scattering Mie size parameter
Extinction coefficient
with
(X or are often used)
2 + 3
Result: numerically demanding approach
Phase function
coefficients
Scattering coefficient
Number of significant terms:
P: Legendre polynominalsa, b: coefficientsMie size parameter (2r/)N: index of refraction
fest
liquid
Angle-Resovled Mie Scattering
Angle: 90º10º
Simulation of Light Scattering Patterns by MiePlot
http://www.philiplaven.com/mieplot.htm
Easy Approach to determinethe size of a microparticle:
Counting of the Mie Modes
B. Steiner et al., Appl. Opt. 38, 1523 (1999)
Inner-Shell Electron Energy Loss Spectroscopy (ISEELS)