New organic crystals as x-ray monochromators: Triphenylbenzene and thalliúm tartrate

The usefulness of analysing crystals for x‐ray spectrometry is governed, to a large extent, by their angular dispersion and reflection efficiency, but other features such as crystal fluorescence must also be taken into account. Experimental results are presented that illustrate the performances of two organic crystals: (i) triphenylbenzene, which constitutes an attractive alternative to ammonium dihydrogen phosphate for the determination of magnesium in cements and other calcium‐containing matrices, and (ii) thallium tartrate, which may be recommended for the determination of sodium and possibly magnesium instead of the widely used thallium acid phthalate.