1. ultrashort laser pulses - freie universitätuserpage.fu-berlin.de/~ruehl/pcsc11.7.17-abb.pdf ·...

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)