Work Group Prof. Dr. F. Temps

Transient electronic absorption

Femtosecond Transient Electronic Absorption Spectroscopy (fs-TEAS) is the most versatile tool for the investigation of ultrafast processes and the main work horse in our group. The molecules in the sample solution contained in a thin (0.1 - 1 mm) flow cell or in a wire-guided free-flowing laminar liquid film are photo-excited by a 20 - 25 fs UV or VIS laser pulse from a wavelength-tunable non-collinear optical parametric amplifier (NOPA) equipped with a prism pulse compressor and an optional frequency-doubling stage. The optical response of the sample is then interrogated as function of pump-probe delay time by a broadband supercontinuum pulse in the UV-VIS or near-IR spectral region generated in sapphire or CaF2

  

fs Transient Electronic Absorption
  
Schematic experimental setup for femtosecond broadband transient electronic absorption spectroscopy.
Our current setup has an additional beam path for single-color detection in the UV.               (c) F. Temps

 

Thanks to a fast frame transfer (FFT) readout CCD camera, single-shot detection electronics at 1 kHz, and a pulse-to-pulse discriminator, we reach a broadband detection sensitivity of ΔOD ≤ 2 × 10-6, at a time resolution of Δt ~ 25 - 35 fs. An additional single-color probe beam (not shown in the figure below) allows us to follow the dynamics at deep-UV wavelengths with a detection sensitivity of ΔOD ≤ 5 × 10-6

Important papers:

  • K. Röttger, S. Wang, F. Renth, J. Bahrenburg, F. Temps, "A Femtosecond Pump-Probe Spectrometer for Dynamics in Transmissive Polymer Films", Appl. Phys. B 118, 185 - 193 (2015). DOI:  10.1007/s00340-014-5967-y
  • K. Röttger, R. Siewertsen, F. Temps, "Ultrafast Electronic Deactivation Dynamics of the Rare Nucleobase Hypoxanthine", Chem. Phys. Lett. 536, 140 - 146 (2012). DOI: 10.1016/j.cplett.2012.03.106
  • F. Renth, M. Foca, A. Petter, F. Temps, "Ultrafast Transient Absorption Spectroscopy of the Photo-Induced Z - E Isomerization of a Photochromic Furylfulgide," Chem. Phys. Lett. 428, 62 - 67 (2006).