Investigation Of Hyperfine Structure Research Articles

Internal dynamics of subunits and bending force constants in weakly bound dimers

Two models for the bending motions of weakly bound dimers which use different coordinate systems have been considered and inter-related. The first approach uses standard internal coordinates and the second uses a model based on the oscillation of each monomer subunit about its centre of mass. The inter-relationship of the two treatments allows information from vibration–rotation spectroscopy and amplitudes, obtained from high resolution investigations of hyperfine structure in dimer spectra, to be combined in the evaluation of bending force constants and in the understanding of internal dynamics of dimers. The procedures developed are first applied to the CH3CN ⋯ HF dimer, for which both types of spectroscopic information are now available, and are then extended to related dimers. Oscillation amplitudes βHav for the HF subunit and the corresponding oscillation force constants kββ are reported for a series of B ⋯ HF dimers as follows: [graphic omitted].

Hyperfine structure investigations in the configuration 4f 125d6s 2 of Tm I by laser-atomic-beam spectroscopy

High resolution laser-atomic-beam spectroscopy has been applied to study the hyperfine structure of transitions starting from metastable states of the configuration 4f125d6s2 of Tm I. Precise values for the hyperfine constants of 8 levels belonging to the configuration 4f125d6s2 and 9 levels belonging to excited odd levels have been determined.

Hyperfine structure investigations in the excited B 3Π 0 + state of IF

IF molecules were prepared in a microwave discharge by using C 3F 7I (heptafluoro-2-iodopropane) or by the direct reaction I 2 + F 2. The hyperfine structure of the rotational transitions J′ + 1- J′ = 5-4 of the vibrational level υ′ = 3 and 6-5 of υ′ = 4 in the excited electronic state B 3Π 0 + of IF has been investigated with the method of microwave—optical double resonance (MODR). From the observed spectra, quadrupole coupling constants eq 3 Q = −558.51(60) MHz, eq 4 Q = −570.73(60) MHz and magnetic spin—rotation coupling constants C l(υ′ = 3) = 230(70), C l(υt́ = 4) = 288(70) kHz were derived. With the scaling by the known atomic quadrupole coupling constants B a comparison of the electric field gradients at the different nuclei is possible and enables qualitative conclusions about the electronic structure considering ionic bond and configuration mixing.

Determination of nuclear spins and moments in a series of radium isotopes

The first investigation of hyperfine structure in radium isotopes has enabled the determination of nuclear spins, magnetic dipole and electric quadrupole moments of the isotopes with mass numbers A = 211, 213, 221, 223, 225, 227 and 229. Isotope shifts in the mass range A = 208−232 have also been measured. These studies were carried out using the technique of on-line collinear fast beam laser spectroscopy.

Nuclear moments and isotope shifts of europium isotopes by hyperfine structure investigations with collinear laser ? Ion beam spectroscopy

Hyperfine structures and isotope shifts of the transition 4f7(8S72/0)6p3/2 (7/2,3/2)4−4f7(8S72/0) 5d9D40,λ=604.95 nm, of stable151Eu and153Eu and radioactive152Eu and154Eu have been investigated by collinear laser — ion beam Spectroscopy. Nuclear quadrupole moments have been derived.

The17O nuclear magnetic shielding in H217O and D217O

The gas phase 17O isotope shift [σ(D2 17O)-σ(H2 17O)] has been measured experimentally and found to be 4·04 (±0·35) p.p.m. This supports an earlier theoretical prediction of 3·69 p.p.m. obtained from an ab initio calculation of the oxygen shielding surface. However, it contrasts with a value of 3·08 (±0·20) p.p.m. measured in the liquid phase. This, combined with the differing gas-to-liquid shifts of H2 17O and D2 17O, confirms the generally accepted belief that hydrogen bonding is stronger in liquid D2O than liquid H2O at the same temperature. Data are presented from which an absolute 17O shielding scale can be established once an atomic beam investigation of 17O hyperfine structure is made.

Impurities and electron localization in V2O5 crystals

AbstractV2O5 crystals doped with different impurities of the Mn+ (n = 1 to 6) type are investigated by the EPR method. It follows from the experiment that all the paramagnetic defects are connected with the impurities present in the crystals. The main paramagnetic centre in V2O5 is an electron localized on two 51V nuclei. There is no local compensation of its charge and so it easily destroys in the course of oxidation. It is shown by hyperfine structure investigation that the electron states are localized in a wide temperature range (4.2 to 290 K). The substitutional impurity tends to occupy the vanadium positions near the VV pair. A complex paramagnetic centre is created with electron density distribution dependence on the donor‐acceptor characteristics of the cations. This results in the nonequivalence of the electron interactions with different vanadium atoms, in different values of the HFS constants for differently doped crystals, and in different valency of the impurity cations. Centres of this type are locally compensated and therefore stable to oxidation or reduction.

Interstellar Scintillations as a Tool for Investigations of Hyperfine Structure in Extragalactic Radio Sources

Attempts to use interstellar scintillations (ISS) to study the fine angular structure of quasars and galactic nuclei have not yet met with any success. The main reason for this lies in the comparatively large angular size of the nuclear structure which has been investigated. If dependencies on wavelength for the scintillation index, flux and angular size of a source are taken into account (Ozernoy and Shishov, 1980), it appears that centimeter wave band rather than decimeter wave range used in previous work is most appropriate for observing ISS.

Hyperfine structure investigations in Sm II by collinear laser spectroscopy and nuclear moments of151Sm

We have measured the hfs of the Sm II linesλλ=656.9 nm and 657.1 nm by collinear laser spectroscopy. From the a-and b-values the ratios of nuclear magnetic dipole and electric quadrupole moments are derived. For151Sm we obtain μ(151)=−0.3622(5) μn and Q(151)=0.52 (5) b.

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(3D1)=−520.536 (3) MHzb(3D1)=17.890 (3) MHza(3D2=415.928 (3) MHzb(3D2)=25.899 (13) MHza(3D3)=456.559 (4) MHzb3D3=47.390 (16) MHz135Ba:a3D1=−465.166 (4) MHzb(3D1)=11.642 (4) MHza(3D2)=371.736(4) MHzb3D2=16.745 (14) MHza(3D3)=408.038 (6) MHzb(3D3)=30.801 (24) MHz

Investigation of hyperfine structure and isotope shift of the 605.5 nm-line of Lu176 by laser spectroscopy

Using a tunable single mode dye laser the hyperfine structure of the transition 5d6s 2 2 D 5/2 — 5d6s6p 4 F 5/2 has been investigated for the Lu-isotopes Lu175 and Lu176. From our measurements the following values for the hyperfine constantsA andB could be deduced Lu176 5d6s6p 4 F 5/2:A=698.4 (0.4) MHz,B=1,564 (10) MHz 5d6s 2 2 D 5/2:A=104.1 (0.3) MHz.B=2,631 (6) MHz Lu175 5d6s6p 4 F 5/2:A=987.2(0.4) MHz,B=1,117(6) MHz. The isotope shift between the line centers has been determined to be IS(176-175, 605.5 nm)=−420(10) MHz.

Electric and magnetic hyperfinestructure investigations in the 5s 25p 3 and 5s 25p 26s Configurations of121, 123Sb

Optical hyperfinestructure investigations in several spectral lines were carried out in the Sb-I spectrum from which for the first time accurate values of the hfs-splitting constantsA andB of the ground configuration 5p3 and also for five of the eight levels of the first excited configuration 5p26s were obtained. With these parameters the influence of core polarization effects is calculated to beac= −6.6(4) mK, (equivalent to a magnetic field of −283(20) kG perp-electron spin). The quadrupole momentQ121= −0.36(4) b (including Sternheimer correction) was obtained with the experimental valuesb3/2= −14.3(1.0) mK and 〈r−3〉 =11.2(3) a.u. andQ123= −0.49(5) b withb3/2= −19.9(1.0) mK resp. This evaluation also yields the relativistic correction factor η= −(C″/C′) · Sr/R′r=1.13(2). —For the first time, too, isotope shift investigations in Sb-I lines were possible which permit to determine the isotope shift constant βCexp= 40(10) mK, and a value δ〈r2〉121, 123=0.12(4) fm2 for the change in the mean square nuclear charge radius between121Sb and123Sb which is about 50 percent of the prediction of the unified nuclear model.

How to Cool Light Detectors and Light Sources Simultaneously

In the field of low level light detection, especially in hyperfine structure investigations, there are two main cooling problems: the cooling of the light source (usually a hollow cathode lamp (HCL)) in order to reduce the Doppler width, and the cooling of the light detector (e.g., a photomultiplier (PM)) to reduce thermal noise, especially the dark-current.

An atomic-beam magnetic resonance (ABMR) system for on-line hyperfine structure measurements in short-lived nuclides

In order to reach short-lived nuclides far from stability for hyperfine structure investigations, the atomic-beam apparatus formerly at Uppsala has been reconstructed and connected on-line with the ISOLDE isotope separator at CERN. The design and performance of the system will be described with emphasis laid on the on-line oven section and the automic detection and control systems.

Recent hyperfine structure investigations in the configurations 4f 136s 2, 4f 136s6p, and 4f 125d6s 2 of Tm I

By use of optical hyperfine structure investigations in the Tm I spectrum theA- values of 20 levels of the configurations 4f 13 6s 6p and 4f 12 5d 6s 2 and theA-value of 4f 13 6s 2 2 F 5/2 were determined very accurately. These data and tenA-factors from former experiments are used for theoretical calculations. 30A-factors have been interpolated from intermediate coupling wave functions using 9 effective mono-electronic parameters. The r.m.s. deviation between experimental and theoreticalA- values amounts to 0.5 10−3 cm−1 and represents 3/100 of the average value of the measuredA-factors.

Hyperfine structure and nuclear moments of99Ru and101Ru

The atomic-beam magnetic-resonance method in combination with the triple resonance technique has been used to determine the nuclear magnetic dipole moments of99Ru and101Ru. The moments are deduced fromrf transition measurements in the5F5 and5F4 states at magnetic fields between 770 and 2400 Oe. In order to reduce the part of the uncertainty of the moments which arises from the uncertainty of the hyperfine structure constants more precise values of the constants than those available up to now were determined from low field measurements. After making corrections for hyperfine and Zeeman interactions with neighbouring atomic states we obtain the following values for the magnetic dipole moments:μ 99=−0.6381 (51)μ N andμ 101=−0.7152 (60)μ N (uncorrected for diamagnetic shielding). The results of the present work combined with the results of an earlier hyperfine structure investigation in the5F multiplet are analysed with respect to the effective-operator formalism. From this analysis we obtain the following values for the electric quadrupole moments:Q 99=0.076 (7) b andQ 101=0.44 (4) b (uncorrected for Sternheimer shielding or antishielding).

Hyperfine structure investigations of some odd levels of Co I by level crossing and optical methods

Using the level crossing technique the ratios and absolute values of the hyperfine structure (hfs) constants of the levelsz4F9/2 andz4F7/2 of the configuration 3d74s4p of Co I were measured:z4F9/2: ¦A¦=(811±12)MHz; ¦B¦=(48±93) MHz;B/A=−0.06±0.11 A>0; B 0; B<0. In addition the hfs constants of three other excited levels of Co I could be determined by optical methods:z4F9/2:A=525±26 MHz;B=200 MHzy4F9/2:A=300±30 MHz;B=−500 MHzy4G11/2:A=315±20 MHz;B=400 MHz.

Hyperfine structure investigation of70As with the ABMR method

Hyperfine structure investigation of70As with the ABMR method

Off-diagonal hyperfine structure investigations in 45Sc with the atomic beam magnetic resonance method

The off-diagonal magnetic dipole hyperfine structure constant has been measured in the atomic ground state 3d4s 2 2 D 3 2 of 45Sc with the atomic beam magnetic resonance method.

Simple system for producing an atomic beam of alkaline earth metastables

A simple system is described which produces an intense atomic beam of alkaline earth atoms in metastable states. This system, which used an arc discharge in the effusion orifice of the atomic beam oven, has been used in hyperfine structure investigations of these states, as well as in the study of their scattering properties.