The term ‛�strong>special crystals� refers to crystal types and multilayers that are not used universally but are

employed in special applications.

LiF(420):

See� for example� “standard types� description of the LiF crystals (200� 220 and 420).

Ge:

A very good crystal for measuring the elements S� P and Cl. In comparison to PET� Ge is characterized

by a higher dispersion and a more stable temperature behavior. Ge suppresses the peaks of the 2nd and

4th order� in particular.

Ge is especially suitable for differentiating between sulphide and sulphate� such as in samples of cement.

Introduction to X-Ray Fluorescence (XRF) Fundamental Principles

ADP:

In practice� ADP is only used for the analysis of Mg and has a higher resolution with a significantly lower

reflectivity compared to the multilayer XS-55. ADP is therefore required where interference peaks can

occur such as in the case of low Mg concentrations in an Al matrix.

TlAP:

TlAP has high resolution but low reflectivity and is recommended for analyzing F and Na if the resolution

of XS-55 is insufficient (e.g. where Na is overlapped by the Zn-L peaks in Zn-rich samples).

DANGER

Disadvantages are the limited lifetime� toxicity� and high price.

InSb:

InSb is a very good crystal for analyzing Si in traces as well as in higher concentrations (e.g. glass). It

replaces PET and is used wherever high precision and great stability is required. The disadvantages are

the limited use (only Si) and the high price.

XS-N:

XS-N is a multilayer with a 2d-value of 11.0 nm� specially optimized for nitrogen.

XS-C:

XS-C is a multilayer with a 2d value of 12.0 nm� specially optimized for carbon.

XS-B:

XS-B is a multilayer with a 2d-value of 19.0 nm� specially optimized for boron and is equally suitable for

the analysis of beryllium.