Showing papers on "Spin states published in 1973"
TL;DR: The present results strongly support the assignment of a low spin ferric structure to the iron ion in oxyhemoglobin.
167 citations
TL;DR: In this article, a spin-projected semi-empirical configuration interaction (CI) was used to estimate the Fe57 Mossbauer isomer-shift calibration α ≡ Δδ/Δϱ(0)=−0.31 to −0.38 a03mm/sec.
Abstract: Molecular orbital calculations are made on six iron complexes, using iterative Huckel methods and, where required for proper description of spin states, a spin-projected semi-empirical configuration interaction (CI). Many integrals are avoided in the CI studies by making direct calculation of energy differences between states. From the calculations are obtained charge and spin bond order matrices, dipole moments, and atomic orbital charges. These quantities are used to calculate charge densities at the Fe nucleus, nuclear quadrupole splittings, and spin populations. From calculations of all six complexes we estimate an Fe57 Mossbauer isomer-shift calibration α ≡ Δδ/Δϱ(0)=−0.31 to −0.38 a03mm/sec.
50 citations
TL;DR: In this article, the in-plane electron spin distribution is highly perturbable and spin-orbit contributions to the relative energies of the spin states become significant in the heavier halobenzenes.
46 citations
TL;DR: In this article, the structures of 53Mn and 53Fe with emphasis on high spin states have been investigated by coincidence, yield, angular distribution, and linear polarization measurements of gamma rays from the 50Cr +? reaction at E? = 14.2 MeV.
Abstract: The structures of 53Mn and 53Fe with emphasis on high spin states have been investigated by coincidence, yield, angular distribution, and linear polarization measurements of gamma rays from the 50Cr + ? reaction at E? = 14.2 MeV. States assigned: in 53Mn: 377 keV (confirmed), 1 289 keV 3/2- (confirmed), 1 441 keV 11/2- (confirmed), 1 621 keV 9/2- (confirmed), 2 564 keV 13/2-, 2 693 keV 15/2-, 2 697 keV 11/2-, 3 426 keV 13/2-, and 3 440 keV 17/2-; in 53Fe: 742 keV 3/2-, 1 328 keV 9/2- (confirmed), 1 424 keV 5/2-, 1 697 keV 7/2-, 2 339 keV 11/2- (confirmed), 3 041 keV 19/2- (confirmed), 3 176 keV 13/2-, 3 463 keV 15/2- and tentatively (4 813 keV 17/2-) Comparison is made with the cross conjugate nuclei within the 1f7/2 shell 43Ca and 43Sc. Feasibility of assignments of residual states in reactions induced by alpha beams of moderate energies is briefly discussed.
45 citations
39 citations
TL;DR: In this article, the de-excitation of these states was studied by in-beam γ-ray spectroscopy and the short-lived radioactivity of the 92Mo target was measured in order to study the decay of 93Ru.
33 citations
30 citations
TL;DR: In this paper, the determinantal form of the Young operator is used to solve the problem of summing over all n! permutations in such expressions, and the authors discuss certain aspects of the theory of symmetric group representations and algebras.
Abstract: Publisher Summary This chapter discusses certain aspects of the theory of symmetric group representations and algebras in an essentially spin-free way with the use of certain Young operators. Specifically, a t basis based upon the Young operator θ N α P α N α has been used. The determinantal form of this operator provides a solution to the problem of summing over all n! permutations in such expressions. The chapter also examines some of the problems of doing quantum mechanical calculations of electronic structures of atoms and molecules for a spin-free Hamiltonian. For a spin-free Hamiltonian the spin functions are essentially determined by symmetry and the dynamical problem of obtaining the energy may be confined to the spatial part of the wave function. There is a unique space-spin function corresponding to the symmetry adapted space functions that are constructed in the chapter.
29 citations
TL;DR: In this article, the de-excitation of the reaction (α, p2nγ) on 90Zr and 92Mo targets was used to populate excited states in 91Nb and 93Tc, respectively.
29 citations
TL;DR: The 12C(12C,pγ)23Na reaction has been used to study the γ-ray deexcitation of levels up to Ex = 10.4 µV in 23Na.
Abstract: The 12C(12C,pγ)23Na reaction has been used to study the γ-ray deexcitation of levels up to Ex = 10.4 MeV in 23Na. Doppler-shift attenuation measurements yielded mean lifetimes or lifetime limits fo...
26 citations
TL;DR: In this article, the authors used the 178 Hf(α, 3n) 179 W reaction to populate rotational states in 179 W and showed that the rotational energies within these bands are successfully explained within the unified model with pairing and Coriolis interactions included if the theoretical Corioli matrix elements are reduced.
TL;DR: Electron spin resonance (ESR) and absorption spectral studies are described which demonstrate two types of cyanide complex of Co(II) human carbonic anhydrase B, showing a certain flexibility of the ligands at the active site as well as a difference in molecular conformation between the liquid and the frozen state.
TL;DR: In this article, the ground state band was observed to have a strong backbending effect atIπ=12+ and four states of a second K = 0 band with spins 9, 11, 13 and 15 were found.
Abstract: High-spin states in156Er have been populated using the (α, 8n) and (16O, 4n) reactions. In the ground state band a strong backbending effect was observed atIπ=12+. Four states of a secondK=0 band with spins 9, 11, 13 and 15 were found. This second band depopulates completely into the 8+ and 10+ members of the ground state band. This is explained by the fact that the upper states of this second band are yrast states and that this band crosses the (gsb)-line atI ≃11.
TL;DR: In this article, the most intense feature of the 155Dy spectrum is a cascade of stretched E2 transitions between levels of the strongly mixed positive parity band arising from the i 13 2, N = 6 shell-model state.
TL;DR: In this article, the nature of disortion of the crystal field symmetry acting on symmetrically coordinated Fe(III) and Mn(II) complexes is investigated, and fine splitting components in the spectra of viscous solutions and of frozen solutions denote the presence of a wide distribution of sites with different zero field splitting terms, part of which are comparable to or greater than, the Zeeman term.
Abstract: The nature of the disortion of the crystal‐field symmetry acting on symmetrically coordinated Fe(III) and Mn(II) complexes is investigated. Fine splitting components in the spectra of viscous solutions and of frozen solutions denote the presence of a wide distribution of sites with different zero‐field splitting terms, part of which are comparable to, or greater than, the Zeeman term. In low‐viscous solutions the mean zero‐field splitting term, which accounts for the linewidth of the ESR spectra, arises from the averaging of essentially the same crystal‐field distribution.
TL;DR: In this article, a complex heavy ion reaction was applied for selective excitation of high spin states in 24Mg using nuclear track emulsions, and the reaction was shown to proceed almost completely via compound mechanism.
Abstract: The reaction12C(14N,d)24Mg is investigated atELab=52 MeV by means or a multigap magnetic spectrograph Angular distributions of levels between 600 and 2021 MeV are measured using nuclear track emulsions By quantitative analysis of the angular distributions (FRDWBA- and Hauser-Feshbach calculations), the reaction is shown to proceed almost completely via compound mechanism The reaction is applied for selective excitation of high spin states in24Mg Evidence is given by this example that under suitably chosen conditions a complex heavy ion reaction can be a powerful means for spin assignments at high excitation energies
TL;DR: In this article, the Bhabha equation is considered in the presence of the electromagnetic interaction introduced through minimal coupling, and it is found to yield the same (anti-) commutators as in the case of a free field.
TL;DR: In this paper, the i.r. spectra of tris(tropolonate) complexes of isoelectronic d5 and d6 metal ions of the first and second transition series are compared.
TL;DR: It is concluded that good correlations of spin state with absorption behavior exist over the entire spectroscopic range from 250 to 2500 nm and that the basic assignments of absorption bands to in-plane charge transfer processes are consistent with these correlations.
Abstract: Characteristic absorption spectra in the ultraviolet, visible, and near infrared regions are correlated with spin state in ferriheme proteins. Weak, diffuse bands in the near infrared exhibit maxima at about 1000-1100 nm (high spin) and at about 1450-1750 nm (low spin). In these and earlier studies such correlations have been established for several ferriheme proteins, but less extensively than in the more well-known cases of Soret and visible band maxima. We have strengthened the correlation in the near infrared by measurements of absorption spectra in Rhodospirillum rubrum cytochrome c′, a variant c-type cytochrome that exhibits a pH-induced transition from high-spin to low-spin state as the pH varies from 6.3 to 13.1. Data are provided on extinction coefficients of characteristic absorption bands at various pH values, obtained by comparison with those measured under the same conditions for horse-heart ferricytochrome c. It is concluded that good correlations of spin state with absorption behavior exist over the entire spectroscopic range from 250 to 2500 nm and that the basic assignments of absorption bands to in-plane charge transfer processes are consistent with these correlations.
TL;DR: In this article, the decay properties of high-spin states of 53Cr have been investigated by means of the 50Ti(α, n)53Cr∗(γ) reaction at Eα = 10.2-14.2 MeV.
TL;DR: In this article, the Schrodinger Equation was used to derive the wave function for a collision involving double ionization by electron impact, and expressions for the total and partial cross section were obtained for singlet and triplet spin states of the target atom.
Abstract: Using the Schrodinger Equation as a starting point, the asymptotic form of the wavefunction is derived for a collision involving double ionization by electron impact, and expressions are obtained for the total and partial cross section. The effect of including exchange is also considered both for singlet and triplet spin states of the target atom.
TL;DR: In this article, the excited states of 35Cl, populated in the 32S(α,p)35Cl reaction at Eα = 12-16 MeV have been studied by γ-γ coincidence, angular distribution and yield function measurements.
Abstract: The excited states of 35Cl, populated in the 32S(α,p)35Cl reaction at Eα = 12-16 MeV have been studied by γ-γ coincidence, angular distribution and yield function measurements The spin values 11/2(-), 11/2(-) and 13/2 are proposed for the new states at 5 407, 5 927 and 6 086 keV respectively
TL;DR: In this paper, strong selectivity has been observed in the population of states in 22 Na up to high excitation energies, and a comparison with Hauser-Feshbach calculations allow us to select strong candidates for the high-spin members of the K π = 3 +, T = 0 and Kπ = 0 +,T = 0 bands in 22 N.
TL;DR: In this article, the ESR spectra of Mn(OMPA)3(ClO4)2 (OMPA = octamethylpyrophosphoramide) doped into the corresponding magnesium host lattice is reported.
TL;DR: In this article, the E2 and M1 reduced transition probabilities between the low lying levels, in the case of79Br and81Br, have been calculated on the core-excitation model.
Abstract: TheE2 andM1 reduced transition probabilities between the low lying levels, in the case of79Br and81Br, have been calculated on the core-excitation model. To account for the observed M1 transition probabilities admixture among the like spin states is considered. In addition, the ground state static moments have been computed. For the same amount of admixture among the like spin states, a good agreement with the experimental results is obtained, for both79Br and81Br. The results are compared with other existing theoretical calculations. From our analysis, we obtain, the quadrupole moment of the first excited 2+ state in the neighbouring even-even nuclei. It is in good agreement with the value calculated on the basis of the anharmonic vibrational model.
TL;DR: In this article, a series of coordination polymers of the type M(II)3[Rh(CN)6]2·xH2O (M(II), = Mn, Fe, Co, Ni, Cu or Zn and x = 7-15) have a f.c.v.unit cell typical of Prussian blue analogs.
TL;DR: In this paper, electron spin resonance and electron nuclear double resonance measurements on free radicals of structure CD3C(COOH)2 in gamma-irradiated single crystals of partially deuterated methyl malonic acid are reported.
Abstract: Electron spin resonance and electron nuclear double resonance measurements on free radicals of structure CD3C(COOH)2 in gamma -irradiated single crystals of partially deuterated methyl malonic acid are reported. The results show that the CD3 groups undergo rapid tunnelling rotation at 4.2 K indicating a lower hindering barrier than in the analogous radical in the undeuterated crystal. Small anomalous shifts of the ENDOR frequencies and broadening of some components of the electron spin resonance hyperfine structure are attributed to a spin rotation interaction arising from the effect of the deuteron quadrupole moment on the hindering barrier, making the probability for tunnelling rotation of the methyl group through 2 pi /3 depend on the spin state of that deuteron which traverses the hindering barrier during the rotation.
01 Jan 1973
TL;DR: In this article, it was shown that the ligand field of a free ion increases with pressure, and that the interelectronic repulsion (Racah) parameters decrease, which increases the probability of a high spin to low spin conversion.
Abstract: As discussed in Chapter 2, the normal ground state of a free ion is the one of maximum multiplicity (Hund’s First Rule). This configuration minimizes the interelectronic repulsion. It was also shown there that a ligand field of octahedral symmetry partially removes the degeneracy, giving a lower lying triplet of π(t2g) symmetry and a higher energy doublet of σ(eg) symmetry. We showed in Chapter 6 that for high spin complexes the ligand field increases significantly with pressure, and that the interelectronic repulsion (Racah) parameters decrease. Thus, on the one hand, with pressure it takes an increasing amount of potential energy to occupy all the orbitals; on the other hand, the decreasing Racah parameters decrease the spin pairing energy. Both of these factors increase the probability of a high spin to low spin conversion. (The increase in field is probably the major effect.) Since Griffith [1] has shown that an intermediate spin configuration is never the most stable in octahedral symmetry, we need only deal with high and low spin states at this point.