X-Ray Fluorescence

TXRF is founded on the same principles of the EDXRF with, however, one significant difference. In contrast to EDXRF, where the primary beam strikes the sample at an angle of 45°, TXRF uses a glancing angle of a few milliradians.

Owing to this grazing incidence, the primary beam is totally reflected. By illuminating the sample with a beam that is being totally reflected, absorption of the beam in the supporting substrate is largely avoided and the associated scattering is greatly reduced. This also reduces the background noise substantially.

A further contribution to the reduction of the background noise is obtained by minimising the thickness of the sample. A small drop of the sample (5-100 microliters of the substance dissolved in an appropriate solvent) is placed on a silica carrier. On evaporation of the solvent a thin film, a few nanometers thick, remains. 

In practice the greater part of the scattering normally arising from the sample and its matrix is eliminated. This is because matrix effect cannot build up within minute residues or thin layers of a sample. Besides its high detection power, simplified quantitative analysis is made possible by an internal standard.

The technique is generally non-destructive and its suitable for solids, liquids, powders and alloys.