Materials Surface Processing Spied by Hyperfine Interactions

There are many aspects of materials surface processing ranging from simple heat treatments to ion implantation or laser surface treatments, e.g. the laser-plasma-coating formation in nitrogen gas, which is called laser nitriding. These methods are often very complicated, involving many basic processes and they have to be optimised for the desired application. Nuclear methods can be successfully applied for this task. First, Ag/Fe multilayers can be prepared by pulsed laser deposition employing an excimer laser. The Ag/Fe system is immiscible and sharp interfaces are expected for that reason. Nevertheless, it will be presented that some intermixing occurs which can be seen by conversion electron Mössbauer spectroscopy with the additional trick of preparing a sensitive $\text{}^{57}$Fe layer at various distances from the interfaces. Several Ag neighbours to the Fe spy-atom can be resolved, whose abundances vary with the location of the $\text{}^{57}$Fe marker layer. It is found that the intermixing at the bottom and top interface of the Fe layers is asymmetric.