Kenichi Yukihira

In-Beam Mössbauer Spectroscopy after GeV-Ion Implantation at an On-line Projectile-Fragments Separator

Mössbauer spectra of 57Mn/57Fe in FZ-Si are measured between 30 and 800 K during implantation of radioactive 57Mn (a half-life of 1.45 min), which are produced via a projectile nuclear fragmentation. The primary implantation energy and the total fluence of 57Mn are 2 GeV and 101057Mn/cm2 typically for one spectrum, respectively. The spectra up to 600 K can be fitted by two components corresponding to Fe atoms on interstitial and substitutional sites. As the temperature is elevated, the area of the interstitial line decreases above 500 K, while the substitutional line increases. At 700 K, both lines merge into a broad single line, which can be interpreted as a motional averaging due to interstitial Fe jumps into vacancies.

In-beam Mössbauer study of 57Mn/ 57Fe in Si following projectile fragmentation and implantation

A new implantation technique is developed for the in-beam Mössbauer spectroscopy with implantation energy of several GeV using the RIken Projectile Separator (RIPS). 57Mn (T1/2 = 1.45 min) ions can be produced and subsequently implanted into any material as a secondary radioactive beam by the projectile-fragmentation reaction of 59 Co beam with a Be target. The Mössbauer spectra of 57Fe in a p-type (100) FZ-Si following β-decay from 57Mn were measured at different temperatures between 30 and 296 K. The spectra can be fitted with two single lines, which are assigned to interstitial and substitutional 57Fe atoms in Si. This technique can be easily applied to other nuclear probes, and therefore, opens a new possibility for Mössbauer spectroscopy complementary to synchrotron techniques.