Investigation of the Zeeman effect in thenp 2-configuration elements

Relativistic and diamagnetic corrections of theg _J -factors of the group IV elements have been calculated, and the correctedg _J -factors are compared with the experimental factors, in order to estimate the departure from LS-coupling and to find evidence of many-body effects.     

Radical pair substitution in chemically induced dynamic nuclear polarization. Co-operative effects

The problem of radical pair substitution in Chemically Induced Dynamic Nuclear Polarization is reconsidered. The singlet—triplet evolution in the radical pairs is described in a continuous fashion, assuming non-disturbance of the electron spin state during the scavenging reaction. The CIDNP effect of the recombination product of the secondary pair is demonstrated to result from the “co-operative effect” of singlet—triplet evolution in both the primary and the secondary pair. The hypothetical one proton case, in which the primary pair has different g-factors and a zero hyperfine interaction, and the secondary pair equal g-factors and a non-zero hyperfine interaction is treated qualitatively. Some examples are discussed in which older models lead to a faulty interpretation of experimental results.     

Calculation of the intermediate coupling between the Hund's cases b and d,for the 3d Rydberg states of H2

The calculation of an intermediate coupling between the Hund's cases b and d is made in the d basis. We apply the calculations to the 3d ¹Σ, ¹Π, and ¹Δ, states of H₂ in order to interpret the measured g-factors of the ¹Σ state. The g-factors of these states obtained by the calculations of other authors in the b basis are compared with our results. We conclude that the criterion of isolation of the 3d Rydberg states of H₂ is not valid     

Nonlinear level crossing spectroscopy of highly excited levels in yttrium using stepwise laser excitation

A technique based on the detection of nonlinear level-crossing resonances in finite magnetic fields has been extended to the study of high-lying electronic levels excited by stepwise excitation with two cw dye lasers. The method has been applied to the determination of |A/g _J | values for four highly excited even-parity levels and two odd-parity levels in yttrium I. Using recently determined values of the magnetic hyperfine interaction constantA, Landég _J -factors have been deduced for these levels with an accuracy of about 1%. The results show significant differences from previous determinations.     

Calculation of the rotational magnetic moments of the ammonia and water molecules

We calculate the rotational magnetic moments and the corresponding g-factors for water and ammonia. Our results are g_xx = 0.397, g_yy = 0.769 and _zz = 0.345 for water and g_xx = g_yy = 0.69 and g_zz = 0.51 for ammonia. The experimental values are g_xx = 0.585, g_yy = 0.742 and g_zz = 0.666 for water and g_xx = g_yy = 0.56 and g_zz = 0.484 for ammonia.     

Ground- and excited stateg-factors of Ba+

We observed the Zeeman-splitting of the 6S _1/2-6P _1/2 resonance transition of Ba⁺ ions (493.4 nm) in a 6 T magnetic field. The ions were stored in a Penning quadrupole trap. From the splitting and the simultaneously measured cyclotron frequency of stored electrons we derived theg-factors of the 6S _1/2 and 6P _1/2 states. The results areg(6S _1/2)=2.00267(20) andg(6P _1/2)=0.66634(22).     

Electron paramagnetic resonance parameters of V2+ ions in both Cd2+ sites of CsCdCl3 crystal

From the perturbation formulas based on a two-spin-orbit-parameter model, the electron paramagnetic resonance (EPR) zero-field splitting (D), g-factors (g_//, g_⊥) and hyperfine structure constants (A_//, A_⊥) for V²⁺ in Cd²⁺(I) and Cd²⁺(II) sites of CsCdCl₃ crystal at room and liquid nitrogen temperatures are calculated. From the calculations, the signs of zero-field splittings and hyperfine structure constants are determined and so all of the EPR parameters are explained reasonably on the basis of the structure data of lattice.     

Correction of k<Subscript>0</Subscript>-factors for non-1/v elements based on neutron spectrum measurements

Neutron spectra were measured by the time of flight method using a rotating disk chopper system in the JRR-3M prompt gamma ray analysis system. Effective g-factors for non-1/v elements such as Cd, Sm and Gd were calculated from the measured neutron spectra and the neutron cross section data, and they was used for correcting the k ₀-factors. The resulting k ₀-factors for the cold and thermal neutron beams agreed within 10%. Furthermore, the prompt gamma ray emission probabilities of Cd, Sm and Gd were derived from the corrected k ₀-factors using other relevant physical constants.     

Charge transfer at oxide surfaces; the adsorption of chlorine and oxygen on MgO

The adsorption of chlorine on MgO in-vacuo is found to lead to an ESR signal with g-factors of 2.008 and 2.002, and to the appearance of a peak in the reflectance spectrum at 440 nm. This reflectance peak is attributed to donor sites, which are probably pairs of O⁻ ions, close to the surface of the MgO. It is shown that γ-irradiation of the O₂/MgO system leads to the formation of similar signals.     

Investigation of 3,5-dichlorosalicylate-copper(II)-(3-pyridylmethanol or N,N′-diethylnicotinamide) complex systems by EPR spectroscopy

Copper(II) complex systems, containing 3,5-dichlorosalicylic acid (3,5-Cl₂salH) and different copper salts (Cu(ac)₂ or CuSO₄), with varying concentrations of 3-pyridylmethanol (ronicol, ron) or N,N′-diethylnicotinamide (denia) as ligands, were prepared. The effects of Cu(II) salts containing anions of different basicity and two different N-donor ligands with varying ligand-to-metal ratio (x) on the formation of the resultant complexes in the water/methanol solutions were studied by EPR spectroscopy at low temperature of 98 K. When ligand concentration was increased, the resolution and signal intensity of the ¹⁴N perpendicular super-hyperfine splitting patterns increased (for ron more progressively), becoming saturated at higher ligand concentrations. In comparing the ronicoland denia-containing systems, both g-factors (g _⊥, g _‖) are systematically higher and the parallel hyperfine splitting (A _‖) systematically lower in denia-containing systems for both Cu(II) salts.     

Prompt k 0-factors and relative gamma-emission intensities for the strong non-1/v absorbers 113Cd, 149Sm, 151Eu and 155,157Gd

Prompt k ₀-factors relative to chlorine and relative g-emission intensities were determined for the strong non-1/v absorbers ¹¹³Cd, ¹⁴⁹Sm, ¹⁵¹Eu,¹⁵⁵Gd and ¹⁵⁷Gd. Measurements were performed using the SNU-KAERI prompt gamma activation analysis (PGAA) facility at the Korea Atomic Energy Research Institute (KAERI). For proper experimental determination of the prompt k ₀-factors, the effective g-factor and cadmium ratio were taken into account, in consideration of the effects from the non-1/v capture cross section and neutron spectrum in the thermal and epithermal energy region. By using the actual spectrum of the neutron beam in this study, the effective g-factor was obtained by calculation, and the influence of epithermal neutrons on the capture rate was corrected by measuring the cadmium ratio for each non-1/v target isotope. The measured prompt k ₀-factors were used to check the consistency between the existing dataset of the absolute g-emission intensity and the 2200 m/s capture cross section for these isotopes.     

Doppler-free laserspectroscopic investigations of hyperfine structure in the atomic cobalt spectrum

Performing Doppler-free laserspectroscopic investigations in the red wavelength region (640–670 nm) we were able to determine 10A-factors and 9B-factors of atomic cobalt levels. Now precise values of 18A-factors and 16B-factors of levels belonging to the configurations (3d+4s)⁹ are known. Fitting of the one-electron radial parameters to introduce agreement between experimental and theoretical hfs constants allows the prediction of hfs constants of not yet investigated fine structure levels. Values of the electric quadrupole moment of the Co⁵⁹ nucleus are determined in two electron configurations. The resulting mean value of the spectroscopic quadrupole moment isQ=0.35(3) barn.     

Paramagnetische organothallium(III)-verbindungen in lösung : II. Esr-untersuchungen paramagnetischer diphenylthallium(III)-komplexemit o-aminophenolen und o-phenylendiaminen

Diphenylthalliumhydroxide reacts in organic solvents with o-aminophenols and o-phenylenediamines to form paramagnetic species, the ESR spectra of which have been investigated. The reaction has been run using 32 ligands in numerous solvents, therefore the general application of the reaction is proved.The ESR spectra of the solutions show typical hydrogen nitrogen hyperfine structures indicating a NH-analogue semiquinone structure for the ligands. Furthermore a very large splitting due to magnetic coupling of the free electron with ²⁰³Tl- and ²⁰⁵Tl-nuclei is observed. In contrast to the paramagnetic diphenylthallium—semiquinone complexes [1a], the different coupling of ²⁰³Tl- and ²⁰⁵Tl-nuclei could be resolved in several cases.The thallium splitting observed increases from the semiquinone complexes (~10 G) to the aminophenol radicals (~40 G) and reaches a maximum value for the o-phenylenediamine derivatives (~90 G). The corresponding g-values decrease strongly in this direction. Thus a clear distinction of these classes of ligands becomes possible.The experimental thallium coupling constants and the g-factors depend largely on the substituent of the ligand, the solvent and the temperature. These effects are interpreted in terms of solvation phenomena.Based on the sum of the observed effects we assume that in all cases the radicals investigated are ion pairs in which the diphenylthallium cation interacts with a new type of ligand, namely NH-analogue semiquinones.     

Local structure distortion and spin Hamiltonian parameters for Cr4+ ions in Cr4+:α-Al2O3 crystals

The relations between the spin Hamiltonian (SH) parameters and crystal structure of Cr⁴⁺:α-Al₂O₃ crystals have been established. On the basis of this, the SH parameters including zero-field splitting parameter D and Zeeman g-factors (g_|| and g_⊥) for Cr⁴⁺ ions in Cr⁴⁺:α-Al₂O₃ crystals, taking into account the spin–spin (SS), spin-other-orbit (SOO) and orbit–orbit (OO) magnetic interactions in addition to the spin–orbit (SO) magnetic interaction, are theoretically investigated using complete diagonalization method (CDM). The theoretical results are in excellent agreement with the experimental ones when the upper three O^2? ions rotate 0.94° toward [1 1 1] axis and the lower three O^2? ions rotate 0.92° toward it. Hence, the local structure distortion effect plays an important role in explaining the spectroscopic properties of Cr⁴⁺ ions in Cr⁴⁺:α-Al₂O₃ crystals. This study shows that for Cr⁴⁺:α-Al₂O₃ the contributions arising from SS, SOO, and OO interactions to the zero-field splitting (ZFS) parameter D are appreciable, whereas those to g_|| and g_⊥ are quite small.     

EPR spectroscopic studies in (30 − x) Li2O-xK2O-10CdO-59B2O3-1MnO2 multi-component glass system

EPR studies were carried out in (30 - x) Li₂O-xK₂O-10CdO-59B₂O₃-1MnO₂ multi-component glass system to understand the effect of the variation in the alkali ratios on the EPR parameters. The observed EPR spectra of Mn²⁺ ion exhibits resonances at g = 2.0, 3.3 and 4.3. The resonance at g = 2.0 is due to Mn²⁺ ions in an environment close to the octahedral symmetry, where as the resonances at g = 3.3 & 4.3 are due to the rhombic surroundings of Mn²⁺ ions. Hyperfine splitting constant values at g = 2.0 and number of paramagnetic centers & paramagnetic susceptibility at different observed resonances were evaluated. These parameters show non linear variation with progressive substitution of Li⁺ ion with K⁺ ions may be due to the changes in cation field strengths and local structural variation due to the variation in mixed alkali ion ratios.     

Electron spin resonance spectra of some phosphonyl radicals and related species

The isotropic ESR spectra of a number of phosphonyl radicals (X₂$\text{P}$O), the dimethylphosphinyl radical, and the phosphoranyl radical (MeO)₃$\text{P}$OBu-t, are described, and accurate values of the phosphorus hyperfine splittings and g-factors are reported. For X₂$\text{P}$O, the value of a(P) increases and the g-factor decreases as the electronegativity of X increases. There is a linear relationship between a(P) for X₂$\text{P}$O and ¹J(PH) for X₂P(O)H, but the same relationship does not hold for Me₂P- and Me₂PH. The spectrum of the di-n-hexylphosphonyl radical shows coupling to two pairs of α-methylene protons, and this non-equivalence is attributed to the pyramidal structure of the phosphonyl radical.     

ESR studies on poly(vinyl chloride) irradiated at medium and high doses

Room temperature gamma irradiation at medium (1-100 kGy) or high (0.9-25 MGy) doses induces different radicals into pure or industrial poly(vinyl chloride) (PVC); the various ESR signals differ by their shapes and/or values of their g-factors and/or peak-to-peak widths but do not give precise information on the chemical structures of the different radicals as the spectra are only poorly resolved. However, looking at the ESR parameters of the different signals and their evolution during natural ageing of the samples, allows us to make correlations between the radio-induced lines in industrial PVC and the ones induced in pure PVC or in PVC additives.     

New continuous Stern-Gerlach effect and a hint of “the” elementary particle

First a Stern-Gerlach type experiment on a beam of electrons similar to Brillouin's 1927 proposal is discussed and shown to be feasible contrary to claims in the literature. Then thecontinuous Stern-Gerlach effect for an individual electron in classical oscillatory motion along the axis of a Penning trap is introduced. The analogy is developed between the classic Stern-Gerlach effect and the continuous one, in which a magnetic bottle replaces the constant field gradient and the place of the glass plate collecting the silver atoms is taken by a meter measuring the frequency of the axial oscillation. Quantum jumps observed with this apparatus in 1977 are exhibited, demonstrating the requirement of a finite time for collapse of the wave function, and the work has been recognized as an early quantum-non-demolitionexperiment. A plot of measuredg-factors vs normalized radius for triton, proton, and electron suggests a new, 10⁴× smaller value for the electron radius, when our electrong-value determined by magnetic resonance and the continuous Stern-Gerlach effect is used. The plot further suggests a progression of ever smaller and heavier fermions until “the” elementary particle, the “cosmon”, is reached. It was formed, when in a random quantum jump the metastable vacuum dissociated into a lone “cosmon/anticosmon” pair, whose subsequent rapid breakup initiated the Big Bang.     

Structure and properties of glasses in the system Li2O–SnO–B2O3

Glasses in the system Li₂O–SnO–B₂O₃ system were prepared by a melt-quenching method. Thermal and viscous properties and local structure of these glasses were investigated. The SnO–B₂O₃ glasses exhibited relatively low glass-transition temperatures (T_g) around 350 °C and excellent thermal stability against crystallization. Viscosity measurements in the vicinity of T_g indicated that the glasses were considerably fragile compared to alkali borate glasses. Fraction of four-coordinated boron was maximized at the composition with 50 mol% SnO and that of nonbridging oxygen, which is not purely ionic in alkali borate systems but partially covalent, augmented with an increase in the SnO content. Correlation between glass properties and structure was discussed in the SnO–B₂O₃ binary system.     

Determination of k 0-factors and validation of k 0-INAA for short-lived nuclides

For standardization of k ₀-based instrumental neutron activation analysis, k ₀-factors for short-lived nuclides (half-lives—11 s to 37 min) of elements F, Se, Sc, Al, V, Ti, Cu, Ca, Mg, I, and Cl with respect to gold (¹⁹⁷Au) were determined using pneumatic carrier facility (PCF) at CIRUS reactor of BARC, Mumbai. Characterization of PCF was carried out by cadmium-ratio method using Au and Zr. The experimental k ₀-factors of the isotopes were found to be in good agreement with the recommended k ₀-factors in most of the cases, as evident from the values of % error and U-score at 95% confidence level. The method was validated by determining concentrations of elements through their short-lived nuclides in one type of the synthetic multielement standards (SMELS-I) obtained from SCK-CEN, Belgium. The method was also applied for determination of concentrations of some of the elements in two reference materials of IAEA, SL-3, and SL-1.