Symmetry Of Core Research Articles

Erratum: Overlapped Stark profiles of coincident x-ray lines as possible diagnostics of core-shell mixing in spherical plasma implosions

One of the most serious obstacles to the attainment of high-gain inertial confinement fusion is the loss of implosion symmetry and mixing of core and shell material, principally as a result of Rayleigh-Taylor instabilities. As a diagnostic of such instabilities, we have investigated the consequences of such mixing on the emergent composite Stark profile of the heliumlike potassium 1{ital s}{sup 2}--1{ital s}2{ital p} {sup 1}{ital P}{sub 1} and hydrogenic chlorine 1{ital s}-3{ital p} lines that are coincident at 3.53 A (3.51 keV). For the case of a chlorine-filled core compressed by a potassium-bearing shell, detailed radiative transfer calculations with self-consistently calculated Stark profiles reveal changes in the overlapped emission profile of these lines when the potassium is assumed mixed into the core. When the potassium remains localized in a distinct shell, its major effect on the chlorine profile is to produce an absorption feature. When the two elements mix to various degrees, the depth of this feature is reduced. This is explained by pumping of the K XVIII 1{ital s}2{ital p} {sup 1}{ital P}{sub 1} state by the Cl L{sub {beta}} line, and obscuration of the potassium emission by the chlorine opacity. Experimental detection of this effect would require spectralmore » resolution of about 2 eV and the ability to discriminate intensity differences of 15% in nearby spectral regions.« less

Overlapped Stark profiles of coincident x-ray lines as possible diagnostics of core-shell mixing in spherical plasma implosions.

One of the most serious obstacles to the attainment of high-gain inertial confinement fusion is the loss of implosion symmetry and mixing of core and shell material, principally as a result of Rayleigh-Taylor instabilities. As a diagnostic of such instabilities, we have investigated the consequences of such mixing on the emergent composite Stark profile of the heliumlike potassium 1{ital s}{sup 2}--1{ital s}2{ital p} {sup 1}{ital P}{sub 1} and hydrogenic chlorine 1{ital s}-3{ital p} lines that are coincident at 3.53 A (3.51 keV). For the case of a chlorine-filled core compressed by a potassium-bearing shell, detailed radiative transfer calculations with self-consistently calculated Stark profiles reveal changes in the overlapped emission profile of these lines when the potassium is assumed mixed into the core. When the potassium remains localized in a distinct shell, its major effect on the chlorine profile is to produce an absorption feature. When the two elements mix to various degrees, the depth of this feature is reduced. This is explained by pumping of the K XVIII 1{ital s}2{ital p} {sup 1}{ital P}{sub 1} state by the Cl L{sub {beta}} line, and obscuration of the potassium emission by the chlorine opacity. Experimental detection of this effect would require spectralmore » resolution of about 2 eV and the ability to discriminate intensity differences of 15% in nearby spectral regions.« less

Motions of the inner core and mantle coupled via mutual gravitation: regular precessional modes

Abstract According to a model of the Earth's interior where the inner core symmetry axis is allowed to deviate from the mantle symmetry axis, motions of the inner core and of the mantle are coupled predominantly via a mutual gravitational torque. Solutions corresponding to regular precession have been studied in detail in this paper in order to produce predictions that may, in principle, be observationally tested. In particular, the Chandler wobble frequency is expected to be split by the presence of the inner core, giving rise to two frequencies on either side. The inner core is found to exhibit a differential rotation at the inner core surface of the order of 1 m s −1 , which corresponds to a period of ∼ 90 days. According to conventional wisdom, which assumes that the inner core co-rotates passively with the rest of the Earth, this value represents an unacceptably fast shear at the inner core-outer core boundary. These two predictions are provisional, however, in the sense that several refinements alluded to in this paper are yet to be undertaken.

Homoleptic methyl compounds of rhodium and iridium(III). X-Ray crystal structures of tetramethylethylenediamine lithium hexamethyl-rhodate(III) and -iridate(III)

The interaction of tetrahydrothiophen (tht) complexes, MCl3(tht)3, M = Rh, Ir, with methyl-lithium in Et2O followed by addition of tetramethylethylenediamine (tmed) gives [Li(tmed)]3[M(Me)6] as thermally and air sensitive crystals; the isostructural compounds have a slightly distorted octahedral MMe6 core with three pairs of cis-methyl groups bridged by Li(tmed) units via Li ⋯ H3C interactions; the symmetry of the MMe6 core is lowered from Oh to D3 by interaction of the MMe6 core with the Li(tmed) units.

Two-group diffusion theory based on separation of variables

The solution of the 3-D, two-group, neutron diffusion equation is reduced to an iterative solution of 1-D algebraic equations for nodal fluxes. The reduction is enabled by the assumption that the flux is separable in x, y and z. Although the detailed flux distribution in a typical LWR environment is not separable, the assumption will nonetheless result in a very appropriate distribution of integrated nodal fluxes. In return, there is no need to approximate the functional (i.e. x) form of the transverse (i.e. y) leakage and the ensuing I-D equations are homogeneous. The theory replaces coupled transverse fluxes with bucklings as dependent variables, therefore along with the flux iteration, there is a buckling update. In some cases the update will be oscillatory, unless strong under-relaxation is used for all cases. Iteration acceleration is nevertheless regained by solving the homogeneous equations as weak-source inhomogeneous, and by using the iteration ratio to extrapolate the power distribution. The code NOXER (Nodal Diffusion by Flux Separation) applies the theory. The 2-D cross-core assembly powers of a PWR, calculated with one mesh per assembly, typically results with an average error of 1% and maximum error of 3%, compared with a high-order, fine-mesh, finite-element calculation. The IBM 4361 and CRAY1 XMP times for generating these results are, respectively, ∼5s and ∼0.25s for an 1 8 core symmetry.

Three dynamical boson-fermion symmetries for odd-odd nuclei

For odd-odd nuclei we introduce three dynamical boson-fermion symnetries associated with jπ=3/2, jυ=3/2 and UB(5) symmetry of the boson core. The corresponding energy formulas and quantum numbers for low-lying states are explicitly given.

Identification of the IR frequencies of the interstitial carbon atom in some M6C (M = Fe, Ru) carbonyl clusters by13 C-enrichment

13C-enriched carbido carbonyl clusters of the type [M6C(CO) n ] z− (M=Fe,n=16,z=2; M=Ru,n=16 ifz=2 andn=17 ifz=0) have been prepared and their IR spectra observed in the 900−600 cm−1 region; the band shifts occurring upon13 C substitution enable the assignment to the stretching modes of the interstitial C atom. Band patterns reflect the symmetry of the M6C core, but the frequencies seem dependent on other molecular features.

Core state vibrational excitations and symmetry breaking in the CK and OK emission spectra of CO2

The CK and OK emission spectra of gaseous CO2 have been recorded in high resolution. From a Franck–Condon fit to the vibrational structure of the spectra, it is shown that C1s ionization leads to a bond length shortening of 2.0 pm, while O1s ionization mainly results in a displacement of the carbon atom of 5 pm, thereby breaking the D∞h symmetry of the molecule. The high resolution allowed the natural lifetime width of the O1s vacancy state to be determined to 0.07 eV and by the use of an accurate calibration procedure the adiabatic x-ray transition energies were determined. These energies were used to obtain accurate binding energies of the core electrons. The O1s binding energies in CO2 were determined to 297.651 and 541.07 eV, respectively.

Observed Lα profiles for two solar flares: 14∶12 UT 15 June, 1973 and 23∶16 UT 21 January, 1974

Photographic observations of the time development of the profile of the Lα line of hydrogen during flares were obtained with the NRL spectrograph on ATM. The profiles for the 15 June, 1973 and 21 January, 1974 flares reported here cover both core and wings of the line. The time sequences begin before flare maximum, and continue well into the decay phase. Careful attention has been given to photometry and absolute calibration. In the case of the 15 June, 1973 flare, data are presented both first-order corrected and uncorrected for incomplete filling of the spectrograph slit by flaring material. Correction of the 21 January, 1974 flare was not possible. We discuss core symmetry and shift, and show that our observations imply integrated flare Lα/Hα intensity ratios within a factor of two of unity for these two flares.

ChemInform Abstract: RESONANCE RAMAN SPECTRA OF TETRAPYRROLE COMPLEXES OF OXOMOLYBDENUM(V)

The resonance Raman spectra of MoO(MEC) and MoO(OEP)(OMe) have been measured in the solid state. Due to low symmetry of the tetrapyrrole core, the former exhibits about 2 times more bands than the latter in the 1650-400-crn-' region. Excitation profile studies on MoO(MEC) show that some tetrapyrrole core vibrations give maxima at the (~(0-0) band and that two bands at 950 cm-' (Mo=O stretching) and 320 cm-I are enhanced more than the core vibrations as the exciting frequency approaches the strong band at 455 nm. These results suggest that the 455-nm band is largely due to a ligand-metal charge-transfer transition and that the 320-cm-' band is assignable to the Mo-N stretching vibration enhanced via such charge transfer. The spectral change caused by laser irradiation of MoO(OEP)(OMe) in the solid state has been attributed to polymerization through the formation of the methoxy bridge between two metal atoms.

Resonance Raman spectra of tetrapyrrole complexes of oxomolybdenum(V)

The resonance Raman spectra of MoO(MEC) and MoO(OEP)(OMe) have been measured in the solid state. Due to low symmetry of the tetrapyrrole core, the former exhibits about 2 times more bands than the latter in the 1650-400-crn-' region. Excitation profile studies on MoO(MEC) show that some tetrapyrrole core vibrations give maxima at the (~(0-0) band and that two bands at 950 cm-' (Mo=O stretching) and 320 cm-I are enhanced more than the core vibrations as the exciting frequency approaches the strong band at 455 nm. These results suggest that the 455-nm band is largely due to a ligand-metal charge-transfer transition and that the 320-cm-' band is assignable to the Mo-N stretching vibration enhanced via such charge transfer. The spectral change caused by laser irradiation of MoO(OEP)(OMe) in the solid state has been attributed to polymerization through the formation of the methoxy bridge between two metal atoms.

MCD spectra of iron-sulfur complexes with or without inorganic sulfur

The magnetic circular dichroism spectra were observed for various iron-sulfur complexes with and without inorganic sulfur as models for rubredoxin and 2-Fe ferredoxin. The MCD band shapes ascribed the bands around 390 and 490 nm to Faraday A terms for mononuclear iron sulfur complexes. These bands are probably assigned to the charge-transfer transitions from the thiol sulfur orbital to the iron t 2 and e 3 d-orbitals, respectively. The MCD magnitudes decreased by more than one-half for binuclear iron-sulfur complexes with inorganic sulfur in comparison with those for the mononuclear complexes. The low MCD magnitude as well as the possible core symmetry as low as D 2 d attributed the MCD bands to Faraday B terms. Incorporation of inorganic sulfur produced new MCD bands, some of which can be assigned to the charge-transfer transitions from the inorganic sulfur orbital to the iron t 2 and e 3 d-orbitals. Among complexes studied here, the bis( o-xylyldithiolato) ferrate(III) monoanion gave the MCD spectrum which resembles that of a rubredoxin. This implies that the MCD spectroscopy also assessed the complex as a good rubredoxin model. However, the binuclear complex bis[ o-xylyldithiolato-μ 2-sulfidoferrate(III)] dianion failed to offer the MCD spectrum similar to that of the spinach ferredoxin.