In certain exceptional cases, capillary samples must be used to measure X-ray absorption spectra (XAS). However, the inhomogeneous thickness of capillary samples causes XAS distortion. This study discusses the distortion and correction of the XAS curve caused by the inhomogeneous thickness of capillary samples. The relationship between the distorted XAS curve μ′d eq (measured values) and the real absorption coefficient μ s d eq (true values) of the sample was established. The distortion was slight and negligible when the vertical size (2h) of the X-ray beam spot was smaller than 60% of the capillary tube’s inner diameter (2R in). When h/R in > 1, X-ray leakage is inevitable and should be avoided during measurement. Partial X-ray leakage caused by an X-ray beam spot size larger than the inner diameter of the capillary tube leads to serious compressed distortion of the XAS curve. When h/R in < 1, the distorted XAS data were well corrected. Possible errors and their influence on the corrected XAS are also discussed. Simulations and corrections for distortions verify the feasibility and effectiveness of the corrected method.
