FEL-light induced changes in thin organic films observed by dynamic Brewster Angle Microscopy

Brewster angle microscopy is a proven technique for the evaluation of thin organic films[1], especially for the observation of phase transitions in monolayers[2]. If a sample is observed under Brewster angle conditions, small changes in the refractive index of the surface can be observed and thus thin layers on the surface can be made visible. Coupling a Brewster angle microscope with a powerful light source like the FEL allows investigation of IR-induced changes in thin organic films. Using the temporal characteristics of the pump and sample illumination light, fast processes (down to 20 µs with camera shutter synchronization or even down to some nanoseconds with synchronized pulsed illumination) can be tracked.

[1] S. Hènon, J. Meunier; Rev. Sci. Instr. 62, 936 (1991)
[2] S. Rivière, S. Hènon et al.; J. Chem. Phys. 101(11), 10045 (1994)