Graphite intercalation compounds (GICs) are a group of layered materials that are suitable as monochromators for cold neutrons. KC₂₄ is a particularly interesting compound in this regard as it features a large c-axis lattice spacing of 8.74 Å, high reflectivity, and the possibility to produce large crystals with mosaicity that matches the beam divergence of cold neutron guides. GICs can be synthesized with different levels of intercalation, known as the stage of the compounds. Each stage displays a specific d-spacing. Impure GIC-monochromators containing multiple stages produce mixing of neutron wavelengths, which complicates data analysis on neutron reflectometers. We discuss the implications of GIC crystal purity and stage contamination for neutron reflectometry and show how GIC crystals can be characterized by time-of-flight neutron diffraction providing an efficient and quantifiable measure of the reflected wavelength spectrum. This allows taking into account multiple wavelength contaminations and ascertains the robustness of reflectometry measurements.

中文翻译：

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用于冷中子仪器的石墨插层化合物（GIC）晶体单色仪：通过飞行中子衍射法表征KC24

石墨插层化合物（GIC）是一组层状材料，适合用作冷中子的单色仪。KC ₂₄在这方面，它是一种特别有趣的化合物，因为它具有8.74Å的大c轴晶格间距，高反射率，并且有可能生产出具有与冷中子导管束发散相匹配的镶嵌性的大晶体。可以通过不同程度的插入（称为化合物阶段）合成GIC。每个阶段均显示特定的d间隔。包含多级的不纯GIC单色仪会产生中子波长的混合，这会使中子反射仪上的数据分析变得复杂。我们讨论了GIC晶体纯度和载物台污染对中子反射测量的影响，并展示了如何通过飞行时间中子衍射来表征GIC晶体，从而提供了一种有效且可量化的反射波长光谱。