AbstractQuantitative de terminations of thickness and composition are presented for 100- to 10,000-A iron-nickel films. Calibration of X-ray intensities with interferometric and calorimetric values give linear plots for films deposited on Mylar or glass substrates. Application of a film-casting technique shows promise of alleviating two of the problems encountered in X-ray spectroscopy, i.e., matrix-effect-caused deviations from proportionality and the lack of standards for calibration of many types of material.