Observation of the gamma resonance of a long-lived 109m Ag isomer using a gravitational gamma-ray spectrometer

Strong natural suppression of the monopole broadening of Mössbauer lines

“…The problem is that the artificial narrowing of lines in long-lived isomers is also problematic [8]. However, the analysis of the experiments performed more than 36 years ago with 109 Ag under natural conditions gave k ~ 10 rather than k > 10 6 , which indicated the natural strong narrowing of the line by a factor of ~10 6 (see [15][16][17][18] and references therein). At the same time, the observation of natural strong narrowing in [15][16][17] was considered questionable in [15,16,18].…”

“…Furthermore, it was assumed [17,18] that natural strong narrowing is reached by the averaging of local d fields to zero because of vibrations of neighbors. This phenomenon is similar to the narrowing of NMR lines in a liquid.…”

“…This phenomenon is similar to the narrowing of NMR lines in a liquid. However, since γ-ray sources in [15][16][17][18] were solid rather than liquid, vibrations in them were insufficiently strong for the suppression of d fields from neighbors. Thus, natural strong narrowing is not similar to narrowing in NMR.…”

“…The absence of a consistent mechanism explaining natural strong narrowing supported an opinion that the observation of this phenomenon was erroneous. At the same time, since neither temperature variations of the experimental geometry as in [15,16] nor instabilities as in [17] existed in [18], the experiments reported in [18] were consistently explained in [19,20]. It is important that the hyperfine structure line in [18] was assumed split in an external magnetic field H ex of about the Earth's field.…”

“…At the same time, since neither temperature variations of the experimental geometry as in [15,16] nor instabilities as in [17] existed in [18], the experiments reported in [18] were consistently explained in [19,20]. It is important that the hyperfine structure line in [18] was assumed split in an external magnetic field H ex of about the Earth's field. Then, the yield of γ-rays for the entire the hyperfine structure as a whole would noticeably depend on the angle ψ between H ex and the wave vector of a γ-ray photon [21].…”