Piezo-QEXAFS with fluorescence detection:: fast time-resolved investigations of dilute specimens

First X-ray absorption spectroscopy experiments with a vibrating piezo-driven double-crystal monochromator (piezo-QEXAFS) and fluorescence detection are reported. It is shown that high-quality XANES spectra can be recorded on a time scale of about 50 ms per spectrum, even for very low concentrations of <10 mmol l(-1) using fluorescence detection. The quality of the spectra, possible applications, as well as present limits of the technique will be discussed.