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The relaxation dynamics of excess electrons in a water jet between 5 and 70°C have been investigated on an ultrashort timescale. We have probed the transient absorption of the system immediately after W multiphoton-ionization with a 266 nm ultrashort laser pulse and a time resolution of about 50 fs. Robe wavelengths ranging from 450 to loo0 nm have been provided by a generated white-light continuum. The data suggest a superposition of geminate recombination of the solvated electrons with their original counter-ions and of relaxation into thermal equilibrium. Relaxation into thermal equilibrium is the much faster process and is completed after about 6 ps while the geminate recombination is much slower, temperature independenL and prevails for at least loops. The here postulated interpretation of the data clearly shows that no other transient states than "hot solvated electrons" are required for an understanding of the observed ultrafast dynamics within our time resolution.

Using ultrafast X-ray diffraction, we study the coherent picosecond lattice dynamics of photoexcited thin films in the two limiting cases, where the photoinduced stress profile decays on a length scale larger and smaller than the film thickness. We solve a unifying analytical model of the strain propagation for acoustic impedance-matched opaque films on a semi-infinite transparent substrate, showing that the lattice dynamics essentially depend on two parameters: One for the spatial profile and one for the amplitude of the strain. We illustrate the results by comparison with high-quality ultrafast X-ray diffraction data of SrRuO3 films on SrTiO3 substrates.

Bacterial adhesion and biofilm formation on surfaces are associated with persistent microbial contamination, biofouling, and the emergence of resistance, thus, calling for new strategies to impede bacterial surface colonization. Using ns-UV laser treatment (wavelength 248 nm and a pulse duration of 20 ns), laser-induced periodic surface structures (LIPSS) featuring different sub-micrometric periods ranging from ~210 to ~610 nm were processed on commercial poly(ethylene terephthalate) (PET) foils. Bacterial adhesion tests revealed that these nanorippled surfaces exhibit a repellence for E. coli that decisively depends on the spatial periods of the LIPSS with the strongest reduction (~91%) in cell adhesion observed for LIPSS periods of 214 nm. Although chemical and structural analyses indicated a moderate laser-induced surface oxidation, a significant influence on the bacterial adhesion was ruled out. Scanning electron microscopy and additional biofilm studies using a pili-deficient E. coli TG1 strain revealed the role of extracellular appendages in the bacterial repellence observed here.