Mechanistic investigations of photoelectrochemical water and methanol oxidation on different titanium dioxide single crystal surfaces Intensity modulated photocurrent spectroscopy (IMPS) TiO2 single crystal photoelectrochemical photocatalysis anatase rutile charge transfer and recombination rate constants. Intensitätsmodulierte Photostromspektroskopie Einkristalloberflächen TiO2 Photoelektroden Photokatalysatoren Rutil Anatas Ladungstransfer und rekombinations Geschwindigkeitskonstanten