No abstract

No abstract

A method using synchrotron radiation parallel beam x-ray optics with a small incidence angle α on the specimen and 2Θ-detector scanning is described for depth profiling analysis of thin films. The instrumentation is the same as used for Θ:2Θ synchrotron parallel beam powder diffractometry, except that the specimen is uncoupled from the detector. There is no profile distortion. Below the critical angle for total reflection αc, the top tens of Angstroms are sampled. Depth profiling is controlled to a few Angstroms using a small α and 0.005° steps. The penetration depth increases to several hundred Angstroms as α approaches αc. Above αc there is a rapid increase in penetration depth to a thousand Angstroms or more and the profiling cannot be sensitively controlled. At grazing incidence the peaks are shifted several tenths of a degree by the x-ray refraction and an experimental procedure for calculating the shifts is described. The method is illustrated with an analysis of iron oxide films.

We have been able to obtain α″-Fe16N2 films using an underlayer template to induce the epitaxial growth of this metastable phase. They are epitaxial in the (001) direction and show single crystallinity in plane. Furthermore, they are deposited by simple reactive nitrogen sputtering. They have an average magnetic moment of 250 emu/g, considerably larger than the moment (217 emu/g) for pure bcc iron. Conversion electron Mössbauer spectroscopy gives three hyperfine fields corresponding to three different iron sites, as expected for this structure.

No abstract