If the photons resulting from a fluorescence process are discriminated with respect to their energy and selectively collected by a detector, the resulting fluorescence yield is a partial fluorescence yield (PFY). Using this method, it is possible to remove the unwanted background radiation in the cases where this distorts the absorption spectra under interest. For thick or high concentrated samples a method free from the artefacts in total fluorescence yield was recently proposed by Achkar et al
.. In “inverse partial fluorescence yield” (iPFY), one uses the fact that the fluorescence of a lower-energy transition, which is not resonantly excited, is reduced, and the reduction is inversely proportional to the absorption of the resonant excitation. The iPFY approach requires the presence of an observer element in the sample, which has an energetically lower lying absorption edge than the element of interest so that it is non-resonantly excited throughout the investigated energy range.The first application of the iPFY method on a liquid sample was recently shown by our group
for aqueous Fe2+
iPFY measuring the iron absorption strength in an aqueous ionic solution via the reduction of the observer intensity (oxygen). For separating the different photon energies, an XES spectrometer in Rowland-circle design can be used. The different detector positions for first-order oxygen and iron emission are sketched with the resulting spectra, upon scanning excitation energy. Figure taken from the review of Lange et al.
- Gotz, Malte D., Mikhail A. Soldatov, Kathrin M. Lange, Nicholas Engel, Ronny Golnak, René Könnecke, Kaan Atak, Wolfgang Eberhardt, and Emad F. Aziz. “Probing Coster–Kronig Transitions in Aqueous Fe2+ Solution Using Inverse Partial and Partial Fluorescence Yield at the L-Edge.” J. Phys. Chem. Lett. (2012): 1619–1623. doi:10.1021/jz300403n.