Historically, the primary result of an EPR experiment is the CW EPR spectrum, typically displayed as the first derivative of the absorption spectrum as a function of the magnetic field. Beyond very qualitative assessments, the detailed analysis of an experimental EPR spectrum is a difficult inverse problem. Given a set of parameters and a model, it is easy to calculate a spectrum, but given an EPR spectrum, it is a challenge to decide on the correct model and find all defining parameters of interest. Programs to simulate and fit CW EPR spectra have been around for a long time. Except for a very well-defined model system, an experimental spectrum of a spin labeled protein is typically a mix of multiple states. This article focuses on the analysis of the CW spectrum in several stages of detail, from qualitative to detailed. The use of the EPR lineshape fitting program MultiComponent developed in the Hubbell lab is used to illustrate common approaches to extract information relevant to protein structure, function, dynamics, and thermodynamics.

从历史上看，EPR 实验的主要结果是 CW EPR 光谱，通常显示为吸收光谱作为磁场函数的一阶导数。除了非常定性的评估之外，实验 EPR 谱的详细分析也是一个困难的逆问题。给定一组参数和一个模型，计算谱很容易，但给定 EPR 谱，决定正确的模型并找到所有感兴趣的定义参数是一个挑战。模拟和拟合 CW EPR 光谱的程序已经存在很长时间了。除了非常明确的模型系统之外，自旋标记蛋白质的实验谱通常是多种状态的混合。本文重点从定性到详细的几个阶段详细分析 CW 频谱。