CONICET | Buscador de Institutos y Recursos Humanos

Recently, the capabilities of the micro-x-ray fluorescencespectroscopy (μXRF) were expanded by the confocal setup. Itconsists of x-ray lenses in the excitation as well as in the detectionchannel. In this configuration, a micro volume definedby the overlap of the foci of both x-ray lenses is analyzed.Scanning this micro volume through the sample, studies in 1-3 dimensions can be performed.The confocal μXRF experiments can be implemented withglass capillaries and polycapillaries. Glass capillaries are usedin the excitation channel with sources of high photon flux likesynchrotron radiation. Half polycapillaries are used almostexclusively in the detection channel. Spatial resolution of theconfocal μXRF depends on the dimensions of the foci of bothx-ray lenses. The dimensions of the probing volume reportedin confocal μXRF experiments are of order of few tens of μm,being the best results obtained with synchrotron radiation [1].Several applications of the confocal μXRF have been shownthe usefulness of the new analytical technique, especially inbiology where it has many potential uses. For biological samples,the absorption of x-rays in the matrix is slight so thetheoretical description of the x-ray fluorescence emission canbe considerable simplified. Effectively, the x-ray absorptioninside the probing volume can be neglected which makes thatthe x-ray fluorescence intensity becomes proportional to theelemental density [2].In the present work the confocal μXRF was applied to studythe rizofiltration with aquatic plants. To implement the technique,a half policapillary made in our laboratory was veryuseful. The success of the experiment confirms that our policapillariesprovide an opportunity to upgrade our laboratorieswith a low cost investment.