The origin of the solvent dependence of fluorescence quantum yields in dipolar merocyanine dyes.

Fluorophores with high quantum yields are desired for a variety of applications. Optimization of promising chromophores requires an understanding of the non-radiative decay channels that compete with the emission of photons. We synthesized a new derivative of the famous laser dye 4-dicyanomethylen-2-methyl-6--dimethylaminostyryl-4-pyran (), , merocyanine 4-(dicyanomethylene)-2--butyl-6-[3-(3-butyl-benzothiazol-2-ylidene)1-propenyl]-4-pyran ().

Space- and time-resolved UV-to-NIR surface spectroscopy and 2D nanoscopy at 1 MHz repetition rate.

We describe a setup for time-resolved photoemission electron microscopy with aberration correction enabling 3 nm spatial resolution and sub-20 fs temporal resolution. The latter is realized by our development of a widely tunable (215-970 nm) noncollinear optical parametric amplifier (NOPA) at 1 MHz repetition rate. We discuss several exemplary applications.