The penetration of chemical reagents through human hair after bleaching has been spatially characterized using infrared microspectroscopy (IMS) with a synchrotron source. Chemical imaging of hair cross sections before and after bleaching was achieved with high contrast, using the peptide and lipid mid-infrared vibrational bands which are characteristic of hair. The ability to make images using functional groups as a contrast mechanism can be applied to studies of other chemical groups, if present, in the structure of the hair. As an example we show how the penetration of an organic active reagent in the hair structure can be quantified with a spatial resolution of few microns. These results demonstrate that synchrotron IMS is a powerful tool for characterizing chemical interactions of hair samples with specific cosmetic materials.

Mossbauer spectroscopy of damage induced by energetic Ar, Kr, and Xe ions in the giga-electronvolt range in two ferrimagnetic oxides, Y3Fe5012 and BaFe120l9, is presented. The enhancement of the paramagnetic phase observed after an irradiation with high-energy deposition (Xe and Kr ions) compared to low-energy deposition (Ar ions) supports a damage mechanism based on the electronic stopping power. Threshold energy-deposition values close to 17 and 25 MeVcm mg ' have thus been determined for Y3Fe50» and BaFelzOl9, respectively. Furthermore, drastic changes in the bulk orientation of the hyperfine magnetic field Hf have been observed in yttrium iron garnet: The Hf distribution is isotropic for Ar irradiations and anisotropic for Xe irradiations, while two types of Hf distributions are observed for Kr irradiations, depending on the values of the deposited energy compared to that of the threshold energy. Comparison with latent-track models is performed.

No abstract

We propose a three-dimensional and high-resolution quantitative image analysis technique for the investigation of the internal microstructure of polymer foams. Microscopy, which is the conventional method of investigation of foams, images only the surface of samples, though, three-dimensional x-ray computed microtomography (μCT) enables the non-destructive imaging of multiple slices of a sample. It is a powerful technique for the examination of porous and multiphase materials. In this paper, we present the application of three-dimensional synchrotron radiation μCT for the characterization of foam samples. After a brief description of the imaging system, we present three-dimensional image-processing tools developed to extract structural parameters quantifying the internal structure of foams. Results of this three-dimensional quantitative image analysis on various types of plasticized poly vinyl chloride foams are presented. This approach provides a tool to study the relationships between the foam microstructures and their physical properties.

No abstract

The electrical resistance of amorphous metallic FeSBl5 ribbons irradiated with 3GeV Xe ions at different tilting angles with respect to the incident ion beam has been measured in situ at 77 K. The results show that irradiation induces large sample growth due to electronic-energy loss effects. The existence of a new mechanism leading to damage creation in metallic alloys by electronic excitation alone is also demonstrated.

No abstract

No abstract