CONICET | Buscador de Institutos y Recursos Humanos

Recently, the capabilities of the micro-x-ray fluorescence spectroscopy (mXRF) were expanded by the confocal setup. It consists of x-ray lenses in the excitation as well as in the detection channel. In this configuration, a micro volume defined by 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 mXRF experiments can be implemented with glass capillaries and polycapillaries. Glass capillaries are used in the excitation channel with sources of high photon flux like synchrotron radiation. Half polycapillaries are used almost exclusively in the detection channel. Spatial resolution of the confocal mXRF depends on the dimensions of the foci of both x-ray lenses. The dimensions of the probing volume reported in confocal mXRF experiments are of order of few tens of mm, being the best results obtained with synchrotron radiation. Several applications of the confocal mXRF have been shown the usefulness of the new analytical technique, especially in biology where it has many potential uses. For biological samples, the absorption of x-rays in the matrix is slight so the theoretical description of the x-ray fluorescence emission can be considerable simplified. Effectively, the x-ray absorption inside the probing volume can be neglected which makes that the x-ray fluorescence intensity becomes proportional to the elemental density. In the present work the confocal mXRF was applied to study the rizofiltration with aquatic plants. To implement the technique, a half policapillary made in our laboratory was very useful. The success of the experiment confirms that our policapillaries provide an opportunity to upgrade our laboratories with a low cost investment.

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