Study on chemical reactions of isolated Mössbauer probes in solid gas matrices using in-beam Mössbauer spectroscopy

In-beam Mossbauer spectra of 57Fe after 57Mn (T 1/2= 1.45 min) implantation into a CH 4 matrix and mixture matrices of CH 4 and Ar at 18 K were measured. The spectrum obtained in the CH 4 matrix was analyzed well with a doublet and a singlet peaks. These components were assigned to two constitutional isomers of Fe(CH 4)\(_{\mathrm {2}}^{\mathrm {+}}\) as derived from density functional theory calculations and the Mossbauer parameters. In the case of the low concentration of CH 4 with an Ar matrix, the Fe + (3d 74s) in the excited state atomic configuration and Fe + (3d 64s 1) in the ground state were observed, as observed in our previous implantation experiment into Ar and Xe matrices. The formation yields of Fe(CH 4)\(_{\mathrm {2}}^{\mathrm {+}}\) are discussed in term of the number of first-nearest-neighbor CH 4 molecules around an Fe + ion.