Total reflection X ray fluorescence analysis using beam guides

HÉCTOR JORGE SÁNCHEZ; MARÍA CECILIA VALENTINUZZI; CARLOS PÉREZ

Río de Janeiro, Brasil

Congreso; Octavo Seminario Latinoamericano de Análisis por Técnicas de Rayos X, SARX2002; 2002

This work reports a study of the properties of beam guides for total reflection XRF analysis when synchrotron radiation is employed. Beam guides consist of two plate reflectors separated by spacers (the distance between reflectors is larger than the coherence length for x rays) and the sample is deposited on the lower reflector, which is larger than the upper one. Photons travel inside the guide by total reflection processes. The use of beam guides  allows to collimate the radiation beam as well as to irradiate the sample in total reflection conditions. Several beam guides were made producing a set of  several devices with different dimensions and materials. The transmitted flux of photons and the excitation intensity on the sample were measured as a function of the angle of incidence. The experimental results were compared with the results obtained using a mathematical model. The limits of detection obtained were compared with the those obtained with standard SR-TXRF.