Department of Chemistry, Wake Forest University, Winston-Salem, North Carolina 27109, USA.
J Chem Phys. 2010 Oct 28;133(16):164501. doi: 10.1063/1.3495954.
An expression for the Casimir-Polder potential between molecules in a homogeneous dispersive and absorptive dielectric medium is derived. The effect of retardation on the interaction energy is discussed by examining the wave-zone and nonretarded limits of the potential. Unlike Lifshitz theory, the interaction energy is not derived from the potential between macroscopic bodies. In this work, a Green function that explicitly accounts for absorption in the medium is obtained. This function leads to possible dissipation effects and presents a near-zone form that vanishes in the limit of nonabsorptive medium. Employing a two-level model, it is shown that the retarded van der Waals dispersion potential in a medium may become repulsive as a consequence of absorption by the medium. It is suggested that the repulsive dispersion force may delay precipitation of nonpolar molecules from a dielectric solvent or even inhibit chemical reaction between them.
推导出了在均匀弥散和吸收介电质中分子之间的 Casimir-Polder 势的表达式。通过考察位势的波区和非滞后极限，讨论了滞后效应对相互作用能的影响。与 Lifshitz 理论不同，相互作用能不是从宏观物体之间的位势推导出来的。在这项工作中，得到了一个明确考虑介质中吸收的格林函数。这个函数导致了可能的耗散效应，并呈现出近区形式，在非吸收介质的极限下消失。采用二能级模型，表明介质中滞后的范德瓦尔斯色散势可能由于介质的吸收而变得排斥。有人认为，排斥的色散力可能会延迟非极性分子从介电溶剂中沉淀出来，甚至抑制它们之间的化学反应。
