W. Semmler

Strong Probe Atom Dependence of the Electric Field Gradient in Bismuth

The nuclear quadrupole interaction of the 8+ isomers in206, 208Po was measured in the semimetallic host Bi. The comparison of the extracted electric field gradient eq for PoBi with the values for the neighboring elements Bi and Pb as probe atoms in Bi reveals a very drastic increase from Pb to Bi and to Po by an order of magnitude: eqPbBi∶eqBiBi∶eqPoBi=1.64(10)∶4.8(3)∶16(2)(all values at room temperature in units of 1017 V/cm2). This behavior is discussed in terms of the changing number of outerp-electrons of the probe atoms.

Temperature dependence of the quadrupole interaction of67Ge and67Zn in s-p metals

The temperature dependence of the electric quadrupole interaction was measured on the 9/2+ isomeric state of67Ge in metallic Zn, Cd, In, and Sn and on the 9/2+ isomeric state of67Zn in Cd metal. For all investigated systems, the temperature dependence reproduces very well aT1.5-relation. The analysis shows that the strength of the temperature dependence in the pure metals is correlated to 1/(M θD2) (θD=Debye-temperature). This favours lattice vibrations as the main component of the temperature dependence of the electric field gradient. The strength of the temperature dependence measured on an impurity atom generally differs from the value of the pure host. Possible explanations for this effect are discussed.

Recoil distance lifetime measurements in 125Xe

Lifetimes of excited states in 125Xe populated in the (12C, 3n) reaction on 116Cd were measured by the recoil distance method. A delayed tagging technique was employed to preferentially detect the non-yrast transitions in the νg72 band system built on the Iπ = 72+, T12 = 140 ns isomer in 125Xe. The following mean lifetimes τ(I)π, Ex) were obtained: 115 ± 25ps (92+, 597 keV), 11.3 ± 1.1 ps (112+, 871 keV), 4.2 ± 1.5ps (132+, 1210 keV), 3.8 ± 1.3ps (152+, 15360 keV); 12.5 ± 1.3 ps (152−, 797 keV). The results are well described within the triaxial-rotor-plus-particle model.

The half-lives of the first and second excited states in 66Ga

Abstract The half-lives of the first and second excited states at 43.9 and 66.3 keV in 66 Ga were determined by measuring the time dependence of the 43.9 and 22.4 keV γ-transition intensities. The levels in 66 Ga were populated by the 66 Za(p, n) 66 Ga and 63 Cu(α, n) 66 Ga reactions. The results are T 1 2 (43.9 keV) = 16(4) ns and T 1 2 (66.3 keV) = 23(2) ns. A g -factor measurement reported in the literature is reanalysed.

Probe specific temperature dependence of the quadrupole interaction of 67Ge in zinc metal

Abstract The quadrupole interaction of the isomeric 9 2 + state of 67Ge was studied in zinc metal as a function of temperature by the DPAD method following the reaction 64Zn(α,n)67Ge. The temperature dependence differs from that of a Zn probe in zinc metal.

Antimony in cadmium — An extreme case of probe atom dependent EFG

The electric field gradient of Sb in Cd was determined by a PAD measurement on112Sb recoil-implanted into a Cd single crystal. We observe an extremely small value compared with known values on the probes Cd, In, and Sn in a Cd matrix. Strong local electronic effects may be responsible for this result.

Electric quadrupole interaction of recoil-implanted zinc in cadmium

The electric quadrupole interaction of the 605 keV 9/2+ state of 67Zn in Cd metal was measured by the recoil implantation technique combined with the DPAD method (DIMPAD). The result, νQ = eQVZZ/h = 39.0(4) MHz (T = 373 K), is compared with the known quadrupole coupling constants in the Zn-Cd system.

Time-differential observation of quadrupole interactions, following recoil implantation of a Ge-probe into Cd, In, Sn, and Sb

We have measured the quadrupole interactions of excited67Ge nuclei in the polyvalent metals Cd, In, Sn, and Sb. The experiments have been performed by the time-differential angular distribution technique, following the reaction64Zn(α, n)67Ge to produce and implant the Ge nuclei into the different metals (DIMPAD). A sandwich target system is used, which allows the application of the DIMPAD-technique for low recoil energies. The extracted electric field gradients are found to depend on the host metal as well as on the solute Ge, an interpretation is suggested on the basis of charge screening effects.