The ultrafast microscope combines a conventional light mitroscope with a femtosecond laser system as the light source and allows to perform spatially and temporally resolved absorption measurements (transient absorption). The spatial resolution is about 1-2 µm and the time resolution about 50-100 fs (femtoseconds). The temporal resolution is realized by the so-called pump-probe concept and image acquisition is performed in raster mode. In addition, pump- and probe pulses can be spatially separated. The wavelength of the pump- and probe pulses can be varied continuously in a range between 500 and 950 nm, or after frequency doubling between 250 and 450 nm, by using optical parametric amplifiers (OPA).
The primary application of the ultrafast microscope is the investigation of light-matter interaction, focusing on nano- and micro-structured materials, as well as quantum materials. In particular, the high time resolution allows real-time investigation of primary ultrafast processes that occur after photoexcitation. These include dynamical processes of the nuclear and electron structure of the materials, as well as the transport of energy and charge carriers. This enables the investigation of diverse questions in the scientific fields of physics, chemistry and materials science.
Prof. Markus Koch
Transient absorption measurements with femtosecond temporal resolution and micrometer spatial resolution at micro- and nanostructured samples.
Methods & Expertise for Research Infrastructure
The Institute of Experimental Physics, where the ultrafast microscope is located, has a long tradition in the spectroscopic study of matter, from isolated atoms and molecules over clusters and nanodroplets to solids. A broad repertoire of techniques both in frequency domain (continuous-wave lasers and frequency combs) and time domain (femto- and attosecond laser pulses) are used, combined with a wide variety of detection methods (photons, electrons, ions). This expertise forms a broad basis for the operation and further development of the ultrafast microscope.