MORPHOLOGICAL INVESTIGATION OF POROUS SAMPLES BY RESONANT BACKSCATTERING SPECTROMETRY

When performing backscattering spectroscopy measurements slightly abov e the energy when a sharp resonance exists in the elastic scattering c ross section a characteristic resonance peak appears in the energy spe ctra of the backscattered particles. Unlike homogeneous samples where the position and width of this peak are mainly determined by the exper imental set-up (incident energy, resonance width, etc.) for porous mat erials the peak width depends on the structure of the sample. This eff ect is caused by fluctuations in the stopping power along the trajecto ries of incident and scattered ions. Using the 3045 keV resonance in t he O-16(alpha, alpha)O-16 reaction for analysing oxidised porous silic on samples, it was demonstrated both experimentally and theoretically that: (i) the widening of the resonance peak is easily observable, (ii ) it is closely related to the actual morphology of the samples and (i ii) it can be applied to determine morphological details, as porosity, average pore diameter and anisotropy of the pore directions. (C) 1998 Elsevier Science B.V.