2012, Wiktorowski, Simon, Fischer, Georg, Daltrozzo, Ewald, Zumbusch, Andreas

Fluorescent dyes are the basis for a broad range of modern techniques in life and material sciences. Consequently, there is a pressing need for the development of new classes of NIR fluorophores in recent years. Pyrrolopyrrole Cyanines (PPCys) are a novel class of NIR chromophores that were first presented in 2007 by Fischer and coworkers.[1] Their optical properties are marked by strong and narrowband NIR absorptions, strong NIR fluorescence and hardly any absorption in the visible range. The absorption maxima can be tuned over a broad range while high fluorescence quantum yields are maintained. PPCys are attractive candidates for labelling applications or as selective NIR absorbers. Moreover, PPCys exhibit very high photostability. Due to these outstanding photophysical properties, PPCys are heading into a promising future as NIR dyes.

2011-02-10, Selm, Romedi, Winterhalder, Martin, Nagy, Andrea, Zumbusch, Andreas, Krauss, Günther, Hanke, Tobias, Sell, Alexander, Leitenstorfer, Alfred

A two branch Er:fiber laser was developed for coherent anti-Stokes Raman scattering (CARS) microspectroscopy. The compact and highly stable light source allows for fast single-frequency CARS microspectroscopy with a wide tuning range from 1150 cm^-1 up to 3800 cm^-1. Single-pass frequency conversion enables easy tunability. The spectral selectivity of the system is shown using polymer beads. Imaging of biological samples is demonstrated on C. elegans and yeast cells. Modification of the light source allows for broadband background-free CARS microspectroscopy. Impulsive excitation of molecular resonances is achieved using an 11 fs pulse at 1210 nm. Broadband excitation gives access to molecular resonances from 0 cm^-1 up to 4000 cm^-1. Time-delayed narrowband probing at 775 nm enables sensitive and high-speed spectral detection of the CARS signal, free of nonresonant background with a resolution of 10 cm^-1.