The Conversion Electron Mössbauer Spectroscopy (CEMS) is highly suitable for the examination of thin films and layers close to the surface. Conversion electrons are counted, which are emitted as a consequence of the de-energizing process of the nucleus that follows after resonant absorption of the Mössbauer radiation. The advantage of this method of investigating the surface with the use of a gas-flow proportional backscatter detector is the simple treatment of the samples (e.g. no high vacuum is necessary) and, in addition, the fact that the usual Mössbauer equipment can be expanded for this measuring method with only a little effort. The RiKon-5 detector is an easy-to-operate 3-wire gas-flow proportional backscatter detector with excellent energy resolution, and is suitable for measurements in the temperature range between 100 K and room temperature. Liquid nitrogen serves as the cooling agent. Furthermore, this detector offers the possibility not only to investigate the surface, but also the entire sample. For this, instead of conversion electrons, the x-rays, emitted after the conversion, which also originate from the deeper areas of the sample, are detected. In addition, the RiKon-5 offers the possibility to perform measurements under an angle of 0° to approx. 60° between the γ-direction and the normal of the surface. The detecting gas for the conversion electron Mössbauer spectroscopy is

a helium/methane mixture for room temperature measurement

a helium/nitrogen mixture for low temperature measurements

The detecting gas for the Mössbauer spectroscopy with re-emitted x-rays is

an argon/methane mixture for room temperature measurements

an argon/nitrogen mixture for low temperature measurement

Three spectra, collected with the RiKon-5 under different operation conditions:

with an argon/methane mixture as the detecting gas

Linewidths:

6.4 keV x-ray-line: 22.7 %

14.4 keV γ-line: 14.7 %

The background was subtracted from the spectrum measured in resonance condition