Mössbauer Effect Studies of the 46.48-keV Level of W¹⁸³

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The recoil-free resonant absorption spectra of the 46.48-keV gamma rays from W¹⁸³ have been studied with the tungsten metal, powder of WO₃ and single crystal of WO₃. The source used was metallic tantalum irradiated with thermal neutrons. The natural line width obtained from the absorption spectra with tungsten metal absorbers is Γ_nat=(2.88±0.06)×10⁻⁶ eV. The mixing ratio E2/M1 is estimated at 0.5%. From the absorption spectra with the absorbers of WO₃ powder and WO₃ single crystal, the quadrupole coupling constant e²qQ(1-R_A) is estimated at −(3.0±0.3)×10⁻⁶ eV. This value is compared with the known value of the coupling constant for W¹⁸² in WO₃. The ratio of the quadrupole moment of the first excited 3/2⁻ state of W¹⁸³ to the first excited 2⁺ state of W¹⁸² is Q^3⁄2−(W¹⁸³)⁄Q²⁺(W¹⁸²)=(0.88±0.14).