X-Ray Fluorescence

GNR analytical instruments, thanks to its 40 years of experience in the field, has tuned-up a huge range of analysers in order to offer the most suitable instrument for any requirements.

GNR X-Ray portfolio cover a huge range of applications for materials characterization and quality control of crystalline or non-crystalline materials such as powders, massive samples, thin films or liquids.

X-Ray Fluorescence (XRF) spectrometry is a non-destructive analytical tecnique based on the characteristic emission of X-Ray photons by atoms when returning to the ground state after an excitation.

This property is used to obtain elemental information from different types of materials in several fields.
The basic Energy-Dispersive XRF (ED-XRF) set-up consists of an X-Ray tube as the excitation source, a sample housing and a semi-conductor detector which allows to discriminate between different energy photons. The angles between the incident X-Ray beam, the sample and detector are equal to 45 degrees in order to minimize the scattered background.

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 degrees, TXRF uses a glancing angle of a few milliradians with the detector positioned very close to the sample at 90 degrees.
Owing to this grazing incidence, the primary beam is totally reflected by a flat substrate (carrier) onto which the sample is deposited in liquid/slurry form and then dried in order to leave only a thin residue film, ideally some nanometer thick. The total reflection condition provides an enhanced fluorescence excitation, while the reduced thickness allows to get rid of any matrix effect: thus, the signal to background ratio is enhanced and for each element a simple linear relationship between its characteristic fluorescence peak intensity and concentration exists.
Quantitative analysis can be performed by adding an internal standard to the sample solution/suspension, i.e. an element which is not present in the original sample (usually Ga, Sc, Co or Y). Then a small droplet, about 5-100 μL, is taken from the solution/suspension with the internal standard and deposited onto the carrier.

The technique is generally non-destructive and it is suitable for solids, liquids, powders and alloys. Depending on the sample, analysis can be carried out on the “as is” specimen or after a treatment step, e.g. dilution, digestion, ashing, on-site enrichment etc. In many cases, the correct sample preparation is instrumental in getting low LOD and accurate qualification.