Abstract: A method for profiling the chemical structure and elemental composition as a function of distance below the exterior surface of a thermoplastic article, and more particularly, to a method for determining the depth of permeation of a modifier into the interior of a thermoplastic article which has been treated with the modifier. The method utilizes a pulsed ultraviolet energy source having a fluence level and pulse duration sufficient to ablate material from the article's exterior surface to a series of successive predetermined distances below the exterior surface to expose successive interior surfaces while causing essentially no physical or chemical damage to each respecting interior surface exposed by ablation. The elemental and chemical compositions of each successive interior surface are analyzed by a surface sensitive spectrographic technique and the spectrographic results are compared to determine the depth of modifier permeation within the thermoplastic article.