Effect of Nuclear Decay Mossbauer Emission Spectroscopy

7 Effect of Nuclear Decay Mossbauer Emission Spectroscopy 

The nuclear decay of radioactive atoms embedded in a host is known to lead to various chemical and physical after effects such as redox processes, bond rupture, and the formation of metastable states [46], A very successful way of investigating such after effects in solid material exploits the Mossbauer effect and has been termed Mossbauer Emission Spectroscopy (MES) or Mossbauer source experiments [47, 48]. For instance, the electron capture (EC) decay of Co to Fe, denoted Co(EC) Fe, in cobalt- or iron-containing compormds has been widely explored. In such MES experiments, the compormd tmder study is usually labeled with Co and then used as the Mossbauer source versus a single-line absorber material such as K4[Fe(CN)6]. The recorded spectrum yields information on the chemical state of the nucleogenic Fe at ca. 10 s, which is approximately the lifetime of the 14.4 keV metastable nuclear state of Fe after nuclear decay. 

HS states by irradiation with light) has contributed to our understanding of the mechanism of the Nuclear Decay Induced Excited Spin State Trapping (NIESST), where the nuclear decay process Co(EC) Fe may be regarded as an internal source for molecular excitation. 

The mechanism of NIESST is essentially the same as for LIESST (see Fig. 8.10), except for the initial excitation step. The electronic structure of the nucleogenic 

Measurements of the lifetimes of NIESST states by time-resolved MES [51] and of LIESST states by time-resolved optical spectroscopy [52] on the very same system (a single crystal of [FC , Mni , (bpy)3] (bpy = bipyridine)) gave similar results. This supports the suggestion that the mechanisms for LIESST and NIESST relaxation are very similar, at least for the low-energy regime. The NIESST effect was also studied in Co(ll) SCO compounds, viz. [ Co/Co(terpy)2]X2 H20 (X = [CIOJ, n = V2,X = Cl , n = 5), where terpy is the tridentate ligand terpyridine 

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