Teflon powder, compressed with the sample, is shown to have excellent properties for the measurement of spectra of polycrystalline actinide and lanthanide compounds by scattered transmission in the region from 350 to 2600 nm. In this way spectra can be obtained using samples which are extremely air and moisture sensitive. For example, the spectrum of pyrophoric tris- (cyclopentadienyl)-uranium (iii) has now been measured for the first time. The resolution, especially in the ir region, is better than obtained by reflection methods, as is shown using ferrocene samples.
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The influence of grain size can be regarded as similar to that in reflection spectroscopy, as is described in detail by Kortüm.14 For compounds of weakly absorbing components one expects that the scattering coefficient will increase with decreasing grain size, so that the absorption will decrease; i.e., the highest intensities are not expected for small grain sizes. This assumption has been confirmed experimentally.
