Speaker
Prof.
Hans Christian Hofsäß
(Georg-August-Universität Göttingen)
Description
Radioactive probe atoms in solids have proven to be unique sensors for internal
magnetic and electrical fields and markers to study diffusion phenomena, impurity
lattice sites and optical properties of impurity atoms. In contrast to conventional
solid state methods applied to study magnetism and structural properties, the use of
radioactive probes as sensors of internal fields is unique since the sensor size
shrinks to the size of an atomic nucleus, about 10-5 of a typical crystal lattice
constant. Moreover the use of radioactive nuclei circumvents sensitivity limitations
due to reaction cross sections and thus radioactive probe techniques are among the
most sensitive techniques in solid state physics.
A variety of technical developments will lead to a much more versatile and efficient
use of radioactive probe techniques in the future. Examples are (i) the fast digital
data acquisition for perturbed angular correlation (PAC) with a time resolution
below 100 ps in conjunction with (ii) next generation ultrafast scintillation
detectors based on rare earth silicates, (iii) detectors for angle resolved
conversion electron Mössbauer spectroscopy, (v) high sensitive position resolving
semiconductor pixel detectors for imaging decay electron angular distributions and
(v) high sensitivity CCD sensors and compact UV lasers for efficient
photoluminescence studies.
In this contribution some possible areas of research are outlined where radioactive
probe techniques may provide new insights into solid state physics problems with a
selectivity and sensitivity not achievable with conventional techniques. Among the
examples discussed will be the application of Mössbauer spectroscopy and PAC to thin
film magnetism, the possible application of PAC to study future high k dielectric
materials, the application of emission channeling to high precision impurity atom
lattice location and the application of radioactive probe techniques for
investigating nanomaterials, surface and interface properties and advanced metallic
alloys such as MAX phases.
Author
Prof.
Hans Christian Hofsäß
(Georg-August-Universität Göttingen)
