1. Contents 1. Mechanisms of ultrafast light-matter interaction A. Dipole interaction B. Displacive excitation of phonons C. Impulsive stimulated Raman and Brillouin scattering D. Scattering and Diffraction 2. Ultrafast optical-frequency methods A. Ellipsometry B. Broadband techniques C. Harmonic generation D. Fluorescence E. 2-D Spectroscopies 3. THz-frequency methods A. Mid-IR and THz interactions with solids B. Difference frequency mixing C. Optical rectification 4. Ultrafast VUV and x-ray frequency methods A. Photoemission spectroscopy B. X-ray absorption spectroscopies C. Coherent imaging D. X-ray diffraction 5. Electron based methods A. Ultrafast electron diffraction B. Electron spectroscopies

2. Time scales in solid state physics 10ns1ns 100ps10ps1ps 100fs10fs1fs Micro electronics Magnetic recording Magnetic recording Optical communication Ti: Saphire lasers High harmonic generation High harmonic generation Thermali- zation Lattice vibrations Ferromagnetic resonance Ferromagnetic resonance Ultrafast demagnetization Ultrafast demagnetization Excitation of an atom Excitation of an atom Recombination of Electron hole pairs Recombination of Electron hole pairs

3. The solid and its excitations Electrons Phonons Spin ss  el ~ 1 ps  es = ?  sl ~ 100 ps?  e < 0.1ps  p < 1 ps

4. The solid and its excitations Electrons Phonons Spin ss  el ~ 1 ps  es = ?  sl ~ 100 ps?  e < 0.1ps  p < 1 ps

5. Fast detector or fast source Fast light source Slow detector Slow light sourceFast detector

6. pump & probe technique: stroboscopic, needs repeatable process! time base adjustable delay probe pump No cats were harmed in our experiments! Courtesy of A. Kirilyuk, U Delft

7. Pump-Probe techniques