Publications by authors named "Franziska Buchner"

Solvated electrons are among the most reductive species in an aqueous environment. Diamond materials have been proposed as a promising source of solvated electrons, but the underlying emission process in water remains elusive so far. Here, we show spectroscopic evidence for the emission of solvated electrons from detonation nanodiamonds upon excitation with both deep ultraviolet (225 nm) and visible (400 nm) light using ultrafast transient absorption.

View Article and Find Full Text PDF

Time-resolved photoelectron spectroscopy is performed on aqueous guanosine solution to study its excited-state relaxation dynamics. Experimental results are complemented by surface hopping dynamic simulations and evaluation of the excited-state ionization energy by Koopmans' theorem. Two alternative models for the relaxation dynamics are discussed.

View Article and Find Full Text PDF

Time-resolved photoelectron spectroscopy is performed on thymine and thymidine in aqueous solution to study the excited-state relaxation dynamics of these molecules. We find two contributions with sub-ps lifetimes in line with recent excited-state QM/MM molecular dynamics simulations (J. Chem.

View Article and Find Full Text PDF

Time-resolved photoelectron spectroscopy is applied to study the excited state dynamics of the DNA base adenine and its ribonucleoside adenosine in aqueous solution for pump and probe photon energies in the range between 4.66 eV and 5.21 eV.

View Article and Find Full Text PDF

Electrokinetic charging of aqueous microjets was characterized by measuring streaming currents as a function of sodium iodide salt concentration. Measured streaming currents at high salt concentrations (up to 0.5 M) varied nonmonotonically with the jet velocity and can be explained by a multipolar charge distribution at the nozzle-water interface.

View Article and Find Full Text PDF

Time-resolved liquid jet photoelectron spectroscopy was used to explore the excited state dynamics at the liquid water surface in the presence of alkali cations. The data were evaluated with the help of ab initio calculations on alkali-water clusters and an extension of these results on the basis of the dielectric continuum model: 160 nm, sub-20 fs vacuum ultraviolet pulses excite water molecules in the solvent shell of Na(+) or K(+) cations and evolve into a transient hydrated complex of alkali-ion and electron. The vertical ionization energy of this transient is about 2.

View Article and Find Full Text PDF

Time-resolved photoelectron spectroscopy at low kinetic energies (≲5 eV) is applied to dilute iodide solutions with different surface and bulk contributions. The results indicate a pronounced surface sensitivity. Signals assigned to solvated electrons near the liquid surface decay rapidly on a sub-ps timescale.

View Article and Find Full Text PDF

We present a novel setup for the investigation of ultrafast dynamic processes in a liquid jet using time-resolved photoelectron spectroscopy. A magnetic-bottle type spectrometer with a high collection efficiency allows the very sensitive detection of photoelectrons emitted from a 10 μm thick liquid jet. This translates into good signal/noise ratio and rapid data acquisition making femtosecond time-resolved experiments feasible.

View Article and Find Full Text PDF

Time-resolved photoelectron spectroscopy was used to study the energetics and dynamics of solvated electrons in aqueous solution. Solvated electrons are generated by ultrafast photodetachment in a 100 mM aqueous NaI solution. Initially, an ensemble of strongly bound ("cold") solvated electrons and an ensemble of weakly bound ("hot") electrons in an unequilibrated solvent environment are observed.

View Article and Find Full Text PDF