Matrix isolation studies of bimetallic molecules of transition metals (Fe-Co, Fe-Ni, Fe-Cu)

Abstract

The matrix isolation technique has been used in conjuction with Mössbauer spectroscopy to study simple molecules of Fe‐X (X=Cu, Ni, Co). The metal atoms were isolated in a solid rare gas matrix at 4.2 K and the molecules were formed in the matrix. It was observed that there is an increase in the electron density at the ⁵⁷Fe nucleus in going from Cu to Ni. The Fe‐Ni molecule is the weakest bond of all the studied cases. It has an isomer shift very close to that of the iron monomer in rare gas solids. In Fe‐Ni the quadrupole splitting of the Mössbauer spectrum is half the value of the Fe‐Fe molecule (4.05 mm/sec), indicating a different orbital ground state for the Fe‐Ni molecule. By contrast Fe‐Co is stronger bound than Fe‐Ni, this being reflected in a more positive isomer shift. Iron‐cobalt multimers were also studied and their magnetic hyperfine splitting determined. Samples of iron‐cobalt isolated in solid argon with a 25 at.% metallic concentrations showed a very similar behavior to that of disordered Fe‐Co alloys. The Fe‐Cu molecule shows a large isomer shift and a small magnetic moment at the iron site.