Electronic structure and indirect spin-spin interactions in bournonite (CuPbSbS3) according to antimony nuclear quadrupole resonance

A complex sulfide CuPbSbS₃ (bournonite) has been studied by the nuclear quadrupole resonance on ^121,123Sb. The temperature dependences of the spectroscopic and relaxation parameters in the temperature range of 10–295 K have been obtained. The crystallochemical features of the environment of the two non-equivalent Sb positions in the unit cell have been revealed from the nuclear quadrupole resonance spectra. The existence of the lattice vibrations with the frequency ω = 110 cm^?1 has been demonstrated on the basis of the temperature dependence of the nuclear quadrupole resonance frequencies. Slow beats have been observed on the decay curve of the spin echo signal. Experimental data have been analyzed in order to reveal the existence of the indirect spin-spin interactions involving Sb atoms. The indirect spin-spin coupling constant has been estimated as J = 2.5 ± 0.5 kHz.     

Hyperfine structure measurements in metastable states of165Ho

The hyperfine structure constants and the electronic g _J factor of the state 4f ¹¹ 6s ^{2 4} I _11/2 belonging to the holmium ground multiplet have been measured using the atomic beam magnetic resonance technique combined with a state-selective laser-induced detection of the resonant atoms. By the same method the g _J factor of the level 4f ¹¹6s ²⁴ I _9/2 was determined, while the hyperfine structures of this metastable state and of two high-lying even parity states have been investigated by high resolution laser spectroscopy. The results for the experimentalA andB factors of all four members of the ground multiplet allow a least-squares evaluation of the three magnetic dipole and the three electric quadrupole effective radial parameters for the configuration 4f ¹¹ 6s ² of holmium, yielding an accurate value for the spectroscopic nuclear electric quadrupole moment:Q _hfs(¹⁶⁵Ho)=2.716(9)b (uncorrected for quadrupole shielding). From a comparison to the quadrupole moments measured in mesic holmium atoms the shielding factor could be estimated.     

Lifetime measurements in166Er

The lifetimes of five states in the ground band, from spin 6⁺ up to spin 14⁺, and of all even states in the gamma band up to spin 12⁺, have been measured in¹⁶⁶Er using the recoil distance method. The reduced electric quadrupole transition probabilities have been determined from the measured lifetimes using previously measured branching ratios, and the mixing between the ground band and theγ-band has been studied. The transitional electric quadrupole moments for the ground band and theγ-band have been deduced and are discussed.     

Dipole structures in 122Xe

High-spin levels in ¹²²Xe have been investigated by γ—γ coincidence measurements using the EUROGAMarray. The reaction ⁹⁶Zr(³⁰Si,4n)¹²²Xe at a beam energy of 135 MeV was used. New structures of competing dipole to quadrupole transitions have been observed. Experimental B(M1)/B(E2) ratios have been extracted and compared with theoretical estimates.     

Quadrupole interaction of8Li and9Li in LiNbO3 and the quadrupole moment of9Li

The quadrupole interaction of nuclear spin polarized⁸Li (I=2) and⁹Li (I=3/2) in LiNbO₃ has been studied at room temperature. The polarization was achieved by optical pumping of a fast atomic beam with circularly polarized laser light. The atoms were implanted into a hexagonal LiNbO₃ single crystal and the quadrupole splitting ofβ-NMR spectra was measured. A ratio of ¦Q(⁹Li)/Q(⁸Li)¦=0.88(4) for the nuclear quadrupole moments was deduced, yielding a new value of ¦Q(⁹Li)¦=25.3 (9) mb for the quadrupole moment of⁹Li.     

Microwave spectrum,quadrupole coupling constants,and barrier to internal rotation of 2-iodopropene

The microwave spectrum of 2-iodopropene has been investigated between 7.7 and 18 GHz. The measured transition frequencies of the ground and two vibrationally excited states have been analyzed using direct diagonalization of the rotational and quadrupole Hamiltonian. The following rotational and quadrupole coupling constants have been determined in a leastsquares fit for the ground state: A = 9285.153(20) MHz; B = 2337.2198(14) MHz; C = 1887.5871(14) MHz; and χ_cc = ?1820.783(33) MHz; χ_ab = 147.5(10) MHz; χ_bb = 957.018(41) MHz; and χ_cc = 863.765(40) MHz. The quadrupole coupling constants have been transformed to their principal axis system. From the splittings of some transitions of the first torsionally excited state a value of V₃ = 905(3) cm^?1 has been found for the threefold barrier hindering the internal rotation of the methyl group.     

Nuclear orientation of198,199Au in Zn and Cd

Low temperature nuclear orientation experiments have been performed with samples prepared by simultaneous implantation of^198,199Au in Zn and Cd single crystals. From the data quadrupole interactions frequencies have been derived as: $$\begin{array}{l} v_Q ({}^{198}Au\underline {Zn} ) = + 162(3)MHz, v_Q ({}^{199}Au\underline {Zn} ) = + 127(2)MHz, \\ v_Q ({}^{198}Au\underline {Cd} ) = + 130(4)MHz and v_Q ({}^{199}Au\underline {Cd} ) = + 107(3)MHz. \\ \end{array}$$ The ratio of the quadrupole moments of¹⁹⁸Au and¹⁹⁹Au is derived asQ ¹⁹⁸/Q ¹⁹⁹=1.26(3).     

Nuclear orientation of156Tb in gadolinium matrix

The anisotropy of the angular distribution of gamma-rays from the decay of¹⁵⁶Tb, oriented in a gadolinium matrix at low temperatures, has been measured at the angles of 0 and π/2 with respect to the applied magnetic field direction in the range of temperatures from 14·6 to 68·4 mK. The temperature dependence of anisotropy was measured for the first time. The parameters of hyperfine magnetic dipole and electric quadrupole splittings have been determined and the values of the magnetic dipole moment ¦Μ¹⁵⁶¦=(9·6±1·3)×10^?27 J/T and the electric quadrupole momentQ ¹⁵⁶=(2·9±0·9)×10^?28 m² of the¹⁵⁶Tb ground state have been calculated. Multipole mixing ratios andB(E2) branching ratios of many gamma-ray transitions occurring in¹⁵⁶Gd have been found and the results have been discussed in terms of the rotational-vibration and pairing-plus-quadrupole models.     

Nuclear moments and charge radii of107–111in determined by laser spectroscopy

Collinear fast beam laser spectroscopy has been used to measure the hyperfine structure and isotope shift in the atomic 5s ² 5p ² P _3/2-5s ² 6s ² S _1/2 transition (λ=451 nm) of^107–111In. Secondary beams of neutron deficient indium isotopes were prepared at the GSI on-line mass separator following fusion evaporation reactions. Magnetic dipole moments and electric quadrupole moments have been determined. The isotope shifts are discussed in terms of the change of the mean square nuclear charge radii and compared with the droplet model predictions and the deformation values calculated from the quadrupole moments.     

Mössbauer study of tektites

Room temperature ⁵⁷Fe Mössbauer spectroscopy has been used to investigate the structural and oxidation state of Fe in tektites from different strewn fields. Spectra have been analyzed in terms of two quadrupole splitting distributions corresponding to Fe^3?+? and Fe^2?+?. All tektites show similar distribution of quadrupole splitting. Each distribution has one peak. The Fe^2?+? sites show a narrow region of Mössbauer line shift (δ) and quadrupole splitting (ε), δ?= 1.02–1.10 mm/s and ε?= 0.85–1.00 mm/s relative to α-Fe. These values have been assigned to intermediate coordination between tetrahedral and octahedral. The Fe^3?+? sites show wider regions of hyperfine parameters: δ?= 0.25–0.45 mm/s and ε?= 0.65–0.90 mm/s. The Fe^3?+?/Fe^2?+? ratio was found to be 0.05–0.15.     

Second-order quadrupole splitting of the55Mn NMR signal in KMno4 powder

In a KMnO₄ powder sample the⁵⁵Mn NMR signal has been observed using a FT pulse spectrometer at magnetic fields between 0.6T and 2.1T. A second-order quadrupole splitting has been found. The quadrupole coupling constant 3e²qQ/(2I(2I?1)h) is (240±10) kHz, the asymmetry parameterη is less than 0.05.     

Radio of the nuclear electric quadrupole moments of 50V (I = 6) and 51V (I = 72)

In SmVO₄ the weak paramagnetism of the Sm³⁺ ions results in a very small paramagnetic shift of the vanadium nuclear resonance; the lines are narrow (?4 kHz) and there is no sign of saturation down to 1.7 K. The quadrupole splittings of the two nuclei have been measured at natural abundance in the same single crystal, giving the following value for the ratio of the nuclear electric quadrupole moments: ∥⁵⁰Q/⁵¹Q∥ = 4.07 (3). Values of ⁵¹Q = ?0.0515 (10) b and ⁵⁰Q = +0.209(6) b are suggested.     

Hyperfine-structure investigation in the 6s5d configuration of135Ba and137Ba

The hyperfine structure of the metastable states of the 6s5d configuration of¹³⁵Ba and¹³⁷Ba has been studied by the atomic-beam magnetic resonance (ABMR) method. The metastable barium states were populated in a plasma-discharge inside the atomic-beam oven. The atoms emerging from the ABMR-apparatus were detected by the use of a dyelaser. Compared to conventional methods this technique has the advantage of being state selective. The following magnetic dipole and electric quadrupole interaction constantsa andb have been obtained:¹³⁷Ba:a(³ D ₁)=?520.536 (3) MHzb(³ D ₁)=17.890 (3) MHza(³D₂=415.928 (3) MHzb(³D₂)=25.899 (13) MHza(³D₃)=456.559 (4) MHzb ³D₃=47.390 (16) MHz¹³⁵Ba:a ³ D ₁=?465.166 (4) MHzb(³D₁)=11.642 (4) MHza(³D₂)=371.736(4) MHzb ³ D ₂=16.745 (14) MHza(³D₃)=408.038 (6) MHzb(³D₃)=30.801 (24) MHz Using these constants and the earlier known ones for the¹ D ₂ state the hyperfine structure for the 6s5d configuration has been analyzed with an effective hyperfine hamiltonian. Hyperfine parameters obtained from the analysis have been compared with theoretical values calculated with relativistic self-consistent-field (SCF) wavefunctions. The quadrupole moments have been evaluated with the following result Q(¹³⁵Ba) =0.20(3)b and Q(¹³⁷Ba) = 0.34(4)b uncorrected for the quadrupole shielding.     

Das Quadrupolmoment des 2,3 MeV-Zustandes in120Sn

Time differentialγγ-angular correlation measurements have been performed to determine the electric interaction of the 2.3 MeVI=5^? state of¹²⁰Sn in different polycristalline antimony compounds. A calibration of the field gradient was achieved by Mößbauerexperiments with the 23.8 keVI=3/2⁺ state in¹¹⁹Sn using identical sources. From the ratio of the measured electric interactions the ratio of the quadrupole moments is deduced as: $$\left| {\frac{{Q(2.3{\mathbf{ }}MeV level,{\mathbf{ }}I = 5^ - ,^{120} Sn)}}{{Q(2.8{\mathbf{ }}keV level,{\mathbf{ }}I = {3 \mathord{\left/ {\vphantom {3 2}} \right. \kern-\nulldelimiterspace} 2}^ + ,^{119} Sn)}}} \right| = 2.86(15)$$ . Using 0.06 (2) b for the quadrupole moment of the 23.8 keV level in¹¹⁹Sn one gets for the quadrupole moment of the 2.3 MeV level in¹²⁰Sn ¦Q(2.3 MeV level,I=5^?,¹²⁰Sn)¦=0.021 (8) b.     

Systematics of Mössbauer parameters in Fe57-doped titanate and germanate ilmenites

The Mössbauer spectra of ilmenite (FeTiO₃), Fe²⁺-doped ilmenites, MTiO₃ (M = Cd, Mn, Zn, Co, Mg and Ni) and MGeO₃ (M = Mn, Zn and Mg), have been studied from 4.2 K to room temperature. Systematic variations in the isomer shift and quadrupole splitting at room temperature are correlated with the change in ionic radii of the host M ions and the c/a ratio of the host crystal, respectively. The quadrupole splittings show a remarkable temperature variation; the magnetic ilmenites show either a sudden increase or a sudden decrease of quadrupole splittings below the Néel temperature, depending on the orientation of the spin axis with respect to the c axis.     

Temperature dependence of17O and14N NQR frequencies in commercial TNT

The temperature dependence of the¹⁷O nuclear quadrupole resonance (NQR) frequencies has been measured in commercial trinitrotoluene by highly sensitive nuclear quadrupole double resonance techniques. The¹⁴N NQR frequencies have been measured in the same sample for comparison. In contrast to the¹⁴N quadrupole coupling constant, the¹⁷O quadrupole constant increases with increasing temperature.     

Electric field gradient at 12 N implanted into ZnO

The nuclear quadrupole interaction of short-lived β-emitter ¹²N(I?=?1, T _1/2?=?11 ms) implanted into a ZnO single crystal has been studied by means of the β-NMR method. We have observed a quadrupole splitting of ¹²N in ZnO at room temperature, from which the electric field gradient (EFG) q?=?+?(8.6 ±1.1) ×10¹⁹ V/m² was deduced assuming axially symmetric EFG with respect to the crystalline c axis. A first principle calculation does not reproduce the data under assumption of the lattice location of ¹²N at the oxygen substitutional site.     

Hyperfine and Zeeman studies of low-lying atomic levels of181Ta and the nuclear electric quadrupole moment

The hyperfine structure of the atomic levels 5d ³ 6s ^{2 4} F _{7/2, 9/2} and⁴ P _1/2 in¹⁸¹Ta has been studied by atomic-beam magnetic-resonance. Using intermediate coupling wave functions derived for the configurations (5d+6s)⁵ the hyperfine structure data of six low-lying metastable states have been analyzed with respect to the effective operator formalism. The effective radial parameters for the magnetic dipole and electric quadrupole interactions are determined from these measurements and compared with relativistic calculations. The value obtained for the spectroscopic quadrupole moment of the¹⁸¹Ta nuclear ground state is Q_hfs=3.44(17) barn (uncorrected for configuration interaction effects).     

Electromagnetic transition strengths and nuclear moments in123Xe

The level structure of¹²³Xe has been studied with the¹¹⁴Cd (¹²C, 3n) and^?Cd (¹³C, 4n) reactions using in-beamγ-ray spectroscopy. The yrast cascade on the low lying odd parity states originating from theh _11/2 neutron orbital has been investigated yielding lifetimesτ of 18(3) ps, 2.2 (4) ns and 17(2) ns for the 15/2^?, 11/2^? and 9/2^? states, respectively. Theg-factor of thet _1/2=5.2 μs isomer has been measured to beg=?0.256(2). From the time differential observation of the electric quadrupole interaction in a¹¹⁴Cd single crystal the spin of this isomer has been determined to be 7/2 and from the coupling constante ² Qq/h=116(2) MHz the quadrupole moment was deduced. The results are discussed in the framework of the triaxial rotor plus particle model.