A espectrometria de fluorescencia de raios-X de energia dispersiva na medida de espessura de filmes polimericos e filmes metalicos espessos

AUTOR(ES)
DATA DE PUBLICAÇÃO

1999

RESUMO

In modern technology there is an increasing need for materials with thickness in nanometer ranges. Energy Dispersive X-Ray Fluorescence Spectrometry (EDXRF) can be considered an important tool for measurements in this range, since the intensity of the elemental X-ray line in a thin film is proportional to its thickness. In this work the purpose was to analyze and develop, by EDXRF, a rapid, indirect method of thickness measurement of polymeric films (with no suitable X-ray absorving element) and also for thick metallic films, which no longer show a correlation between X-ray intensity and thickness. In both cases, a metallic target was used as a substrate for the films and the attenuation of the substrate line intensity was measured. Films of poly(vinyl chloride) - PVC, poly(ethylene terephthalate) - PET, poly(tetrafluoroethylene) - PTFE, polyethylene - PE, polypropylene - PP, cellophane and aluminium, all from commercial sources, were evaluated, with PP being used for testing the accuracy of the method. Metallic lead, copper, tin and aluminium were tested as substrate, with aluminium used for films showing lower sensitivity. The results show that the method is fast; there are cases in which the measurement can be done in less than 100 seconds. The correlation coefficient values in the analytical curves showed that the technique is practicable (in some cases, R is equal to 1,0000). The limits of detection (LD between 0,12 and 20,29 mm) showed applicable values for real samples. The initial values of thickness for each film were determined by Scanning Electron Microscopy (SEM) and the mathematical expression from calibration by EDXRF are specific for each film and substrate. The aluminium metallic film produced the best results in terms of sensitivity.

ASSUNTO(S)

espectroscopia de raio x filmes finos

ACESSO AO ARTIGO

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