No abstract

The molecular beam electric resonance technique has been used to examine the hyperfine spectrum of LiI7 to determine the nuclear hexadecapole interaction of the iodine nucleus. The nuclear magnetic octupole interaction was also considered but found to be marginally significant. A total of 172 transitions in vibrational states 0-3 and rotational states 1-6 have been included in a fit to determine the iodine nuclear quadrupole, spin-rotation, and hexadecapole interactions, the lithium quadrupole and spin-rotation interactions, and the tensor and scalar parts of the spin-spin interaction. Vibration and rotation dependencies of these constants have been determined. The results include: eHh=−0.0151(30), eQIqI=−194351.212(17)−8279.521(46)(v+1/2)+100.616(34)(v+1/2)2−0.3949(73)(v+1/2)3−6.41977(50)J(J+1)+0.10593(33)(v+1/2)J(J+1),eQLiqLi=172.613(52)−3.26(14)(v+1/2)+0.00145(87)J(J+1),cI=6.80260(32)+0.00303(49)(v+1/2)−0.000118(13)J(J+1), cLi=0.75872(72)−0.0088(11)(v+1/2), c3=0.62834(68)−0.0050(11)(v+1/2), c4=0.06223(36)+0.00041(26)(v+1/2), and eΩIωI′=0.000112(73), all in kHz with one standard deviation uncertainties for the last 2 digits in ( ).

Single crystals of the cubic perovskite host, potassium tantalate (KTa0 3 ), doped with iron group, lanthanide, and actinide impurities have been investigated using the technique of electron paramagnetic resonance (EPR). The EPR spectra of Yb 3 + and US + have been observed for the first. time in potassi~m tan~ate by employing crystals co-doped with both impurities. Multiple dopIng of the matenal dunng the crystal growth process avoided the production of semiconducting KTa0 3 and resulted in the incorporation of adequate concentrations of the trivalent lanthanide ion Yb H . The EPR results indicate that Yb 3 + occupies a site in which the local symmetry is axial as a result of nearby charge compensation. Pentavalent uranium is found to occupy a substitutional cubic symmetry site. EPR investigations of Cu 2 +, Co 2 + , Mn 2 + , Ni 3 +, and Fe H were also carried out.

The molecular beam electric resonance technique has been used to examine the hyperfine spectrum of CsF to determine the nuclear quadrupole interaction of the cesium nucleus. A total of 95 transitions in vibrational states vϭ0Ϫ5 and rotational states Jϭ1Ϫ8 have been included in a fit to determine the cesium nuclear quadrupole and spin-rotation interactions, the fluorine spin-rotation interaction, and the tensor and scalar parts of the spin-spin interaction. Vibration and rotation dependencies of these constants have been determined, allowing correction for zero point vibration effects. This experimental Cs nuclear quadrupole coupling constant when combined with the electric field gradient calculated using a relativistic coupled cluster method yields a nuclear quadrupole moment of the Cs nucleus equal to eQϭϪ3.43098 mbarn. The vibrational dependence of the coupling constant is smaller than the theoretical estimate. The coupling constants we have determined are the following: eQ Cs q Cs ϭ1245.598(10)Ϫ14.322(25)(vϩ1/2)ϩ0.080(14) ϫ(vϩ1/2) 2 ϩ0.0040(22)(vϩ1/2) 3 Ϫ0.00209(59)J(Jϩ1)ϩ0.00048(40)(vϩ1/2)J(Jϩ1), c Cs ϭ0.66177(14)Ϫ0.01509(28)(vϩ1/2)ϩ0.000550(94)(vϩ1/2) 2 , c F ϭ15.08163(84)Ϫ0.1744(14) ϫ(vϩ1/2)ϩ0.00234(41)(vϩ1/2) 2 Ϫ0.000093(13)J(Jϩ1), c 3 ϭ0.92713(53)Ϫ0.00917(93)(v ϩ1/2)ϩ0.00097(29)(vϩ1/2) 2 , c 4 ϭ0.62745(30)Ϫ0.00903(22)(vϩ1/2). All values are in kHz units, with one standard deviation uncertainty estimates in the last two digits shown in ().

No abstract

A 7% hyperfine anomaly is found in Mbssbauer measurements of the 73-keV transition in 193 Ir. A 2% difference is found between the anomalies in antiferromagnetic IrF 6 and Ir-Fe alloy. The difference is ascribed to orbital contributions which differ for the two iridium environments. By using known details of IrF 6 we find the orbital field in the Ir-Fe to be # 7 =+335 ±200 kOe.We have observed a 7% hyperfine anomaly between the ground state and first excited state in i93j r k v Mossbauer effect measurement, and a difference between the anomalies for iridium in ferromagnetic and antiferromagnetic environments. We are able to use the results to partition the hyperfine field at 193 Ir in an Ir-Fe alloy into a contribution due to a Fermi contact interaction and one due to noncontact fields, the latter being primarily orbital in origin. It is chiefly upon this new magnetic technique that we wish to report. The measurements of the anomaly will be treated briefly here and in detail in a later publication. 1 Anomalous hyperfine interaction describes the difference between a nuclear magnetic moment measured in a uniform field and the moment measured in a magnetic field of hyperfine origin. 2 ' 3 Since a hyperfine field is observable only in a product with a nuclear moment, the anomaly is observed by comparing the ratio of two moments or nuclear g factors measured in the two types of field. Many such anomalies between the ground states of a pair of isotopes have been measured, for example by atomic-beam techniques. Grodzins and Blum 4 made the first MSssbauer type measurement of the anomaly between two states of the same nucleus (the ground state and first excited state in 57 Fe), where it was found to be marginally small.A large anomaly might be expected to be present in the iridium nuclei 191 Ir and 193 Ir. 5 The relatively large size of the nucleus results in a considerable variation of electron density over the nuclear radius. The contact hyperfine field, which depends on the density, is thus variable over the radius. The orbital and spin motions of the unpaired nucleons cause different radial distributions of magnetic moment and therefore contribute differently to the overall interaction in the radially varying density. The | + ground state of the odd-proton nucleus 193 Ir, for example, is favored for the effect because insofar as it is d 3/2 in character, the orbital and spin contributions to the nuclear moment tend to cancel, and a minor difference in the separate interactions shows up as a relatively large effect. The | + excited state at 73 keV is not so especially favored. It is the transition between these two states which we use.We measured the ratio g*/g° of excited-state to ground-state nuclear g factors in an external field of 73 kG supplied by a superconducting magnet. The absorber was iridium metal and the source 193 Os from neutron capture in 192 Os metal. The source itself has a small quadrupole splitting 6 which was taken into account in the fitting. The spectrum is incompletely resolved and contains ...

No abstract

A molecular beam spectrometer has been used to observe the hyperfine spectrum and determine the electric dipole moment of the KOH molecule. This EDM had never been measured previously, although theoretical calculations had been made. A refined line shape fitting procedure has helped make possible this determination from the molecular beam hyperfine spectrum. The value of the EDM, which we found for the ground vibrational state, is 7.415±0.002 debye. The hyperfine constants, including the potassium nuclear quadrupole, both spin–rotation interactions, and the tensor and scalar spin–spin interactions have been determined for several vibrational states.