Mapping of X-ray induced luminescence using a SNOM probe

In this work we show the feasibility of simultaneous topographic and luminescence mapping with an home-built Shear-Force Microscope under X-ray irradiation with a tabletop microfocused X-ray source (maximum electric power of 30 W). A commercial fluorescent screen, containing europium uranyl compounds, is used as test sample. Simultaneous topography and luminescence maps on the fluorescent screen are first obtained with the apparatus. The two images totally overlap, however the luminescence is not homogeneous on the whole scanned area. Moreover, a photoluminescence spectrum is presented with a good signal-to-noise ratio under X-ray irradiation on a grain of the fluorescent screen and shows peaks in agreement with Europium uranyl compounds. A ZnO/ZnS powder mixture embedded in PMMA is then studied with the same equipment. A 20 μm-wide grain is clearly visible on the topographic image. With the instrument, the grain could be unambiguously identified as containing mainly ZnO.