Hamaker constants of inorganic materials
Hamaker constants of inorganic materials
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DOI：
10.1016/s0001-8686(97)00003-1
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发表时间：
1997-07-18
影响因子：
15.6
通讯作者：
Bergstrom, L
中科院分区：
文献类型：
--
作者：
Bergstrom, L
使用Lifshitz理论计算Hamaker常数需要准确的介电数据，特别是在紫外光谱区，并使用方便和适当的数学表示。在这篇评论中，一个多振荡器模型-所谓的Ninham-Parsegian（N-P）表示-已被使用和光谱参数为31种不同的无机材料（包括金刚石）已产生的严格评估的光学数据或从文献中收集。对于大多数材料，使用双振荡器模型（一个UV项和一个IR项），但在可用时包括更详细的表示。本文给出的光谱参数可以与以前的数据相结合，主要集中在碳氢化合物和有机体系，产生一个广泛的固体和液体的光谱数据库，使Lifshitz计算Hamaker常数的许多材料组合。这些计算是使用完整的Lifshitz理论进行的。还涵盖了原子力显微镜研究中四种常用材料的不对称组合A（1v 3）和A（1 w3）：二氧化硅、无定形氮化硅、蓝宝石和白云母。与以前的计算相比，使用新的水介电表示导致A（1 w1）的值显著降低。分析近似完整的Lifshitz理论进行了评估，并发现给令人惊讶的准确结果（塔博尔-温特顿近似）的A（1v 1）时，IR的贡献是次要的。试图通过在n（0）和ω（UV）之间建立某种标度关系来使TW近似更一般化，但收效甚微;仅共价氧化物的UV光谱参数，硫化物和氮化物可以拟合成一个简单的幂律关系。在这项研究中的Lifshitz计算进行了比较，与另一种方法，其中更详细的介电表示在可见光-紫外光谱范围是通过Kramers-Kronig（K-K）变换的反射率数据在较宽的频率范围内获得的。尽管在介电信息的差异，这两种方法一般产生非延迟Hamaker常数，不显着不同。这并不适用于所有的材料，例如水，其中必须使用具有多个振子的N-P表示或：K-K表示的更详细的表示。结果表明，在后一种方法中忽略静态和低频的贡献可能会导致显着低估的值为A（1 w1）时，色散的贡献变得非常小。
Calculations of Hamaker constants using Lifshitz theory require the availability of accurate dielectric data, especially in the ultraviolet spectral legion, and the use of a convenient and appropriate mathematical representation. In this review, a multiple oscillator model - the so-called Ninham-Parsegian (N-P) representation - has been used and spectral parameters for 31 different inorganic materials (including diamond) have been generated from critically evaluated optical data or collected from the literature. For most materials, a two-oscillator model (one UV and one IR term) was used but more detailed representations were included when available. The spectral parameters presented here can be combined with previous data, mainly focused on hydrocarbon and organic systems, to yield an extensive spectral data base for both solids and liquids enabling Lifshitz calculations of Hamaker constants for many materials combinations.Non-retarded Hamaker constants for symmetric material combinations across vacuum (A(1v1)) and water (A(1w1)) have been calculated for the different materials; these calculations were performed using the full Lifshitz theory. Asymmetric combinations, A(1v3) and A(1w3), against four commonly used materials in atomic force microscopy studies: silica, amorphous silicon nitride, sapphire, and muscovite mica, have also been covered. The use of a new dielectric representation for water resulted in significantly lower values of A(1w1) compared to previous calculations. Analytical approximations to the full Lifshitz theory were evaluated and found to give surprisingly accurate results (the Tabor-Winterton approximation) for A(1v1) when the IR contribution is of minor importance. An attempt to make the TW approximation more general by establishing some scaling relationship between n(0) and omega(UV) was met with little success; only the UV spectral parameters of the covalent oxides, sulphides and nitrides may be fitted to a simple power law relation.The Lifshitz calculations in this study were compared with an alternative method where a more detailed dielectric representation in the visible-ultraviolet spectral range was obtained through Kramers-Kronig (K-K) transformation of reflectivity data over a broad frequency range. Despite the difference in dielectric information, the two methods generally yield non-retarded Hamaker constants which do not differ significantly. This is not true for all materials, e.g. water, where a more detailed representation using either an N-P representation with several oscillators or the: K-K representation must be used. It was shown that the omission of the static and low frequency contribution in the latter method may result in a significant underestimation of the value for A(1w1) when the dispersive contribution becomes very small.