The electronic spectrum of gaseous SnS

Observations of the spectrum of SnS excited in chemiluminescence have led to the characterization of two low-lying excited states of SnS, $\text{a}\text{Ω}\text{1(}{}^3\text{Σ}{}^{\mathrm{+}}\text{)}$, with T_e = 18 143.9 cm^?1, and $\text{A0}{}^{\mathrm{+}}\text{(}{}^3\text{Π}\text{)}$, with T_e = 22 021.3 cm^?1. Extended rotational analyses of the perturbed bands observed in the absorption spectrum enable assignments to be suggested for the components $\text{Ω}\text{0}{}^{\mathrm{+}}$ and 1 of ³Σ^? and $\text{Ω}\text{1}$ of ³Π.     

The kinship of E. H. Moore and R. L. Moore

Evidence is presented that E. H. Moore and R. L. Moore were seventh cousins.     

ESDIAD studies of fluorine and chlorine adsorption at Si(100)

Electron stimulated desorption ion angular distribution (ESDIAD) patterns are reported for fluorine and chlorine adsorbed at the silicon (100) surface. Analytical and numerical methods of establishing the degree of angular compression imposed by the sample bias frequently employed in ESDIAD measurements, are described. Measurements of the two halogen adsorbates contrast strongly, particularly with regard to their response to annealing in the temperature range 300 to 1000 K. In the case of F⁺ desorption, a minimum in ion intensity occurs along the surface normal. Maxima in the ion production are observed at a polar angle of 30°, and in registry with the principal crystal axes as reported by other workers. Cl⁺ ion angular distributions however, indicate a mixture of normal and off-normal emission for adsorption at ≤ 300 K. This pattern transforms, irreversibly, to a single maximum directed along the surface normal in response to annealing to 650 K. The transformation is linked to the thermal depopulation of one adsorption state, leaving a higher binding energy state intact.     

Level structure of 184W from the 183W(n, γ) reaction

The level structure of ¹⁸⁴W has been studied from the prompt γ-rays emitted following the capture of both thermal and 2 keV neutrons by ¹⁸³W. Energies and intensities were measured for both the primary and the secondary (low-energy) prompt γ-rays. From these data, a level scheme is proposed for ¹⁸⁴W in which all the I^π = 0⁺, 1⁺ and 2⁺ states below ≈ 2.0 MeV are observed. Where possible, rotational-band assignments have been made to these and other levels. Additional evidence is presented which confirms the 1130 keV state as being the band head of a K^π = 2^? octupole vibrational band. Admixed K^π = 0⁺ and 2⁺ bands are established at 1322 and 1386 keV, respectively, with the I^π = 2⁺ states (at 1431 and 1386 keV) having a mutual admixture of ≈ 12%. In the energy region above 1.5 MeV, the following bands and band-head energies are identified: K^π = 1⁺, 1613 keV; K^π = 0⁺, 1614 keV; K^π = 1⁺, 1713 keV; K^π = 2⁺, 1877 keV. The neutron binding energy in ¹⁸⁴W has been determined to be 7411.1±0.6 keV. The band structure of the 1613 keV (1⁺) and 1614 keV (0⁺) bands is observed to be strongly distorted, the observed $\text{A (}\text{h}\text{?}{}^2\text{/2}\text{I}\text{)}$ values being ≈ 3.6 keV and ≈ 32 keV, respectively. This strong distortion is shown to be explainable in terms of Coriolis coupling of reasonable strength between the two bands. A similar explanation is shown to account for the somewhat less anomalous A-values (22.8 keV and 14.0 keV, respectively) of the 2⁺ band at 1386 keV and the 3⁺ band at 1425 keV. The results of a phenomenological fiveband-mixing analysis involving the K^π = 0⁺ and 2⁺ bands below ≈ 1.5 MeV are presented and discussed. These calculations indicate, among other things, that the direct E2 matrix element connecting the 1322 keV, K^π = 0⁺ band and the ground-state band is quite small, possibly zero. They also indicate that a nonzero E2 matrix element exists between this excited K^π = 0⁺ band and the γ-vibrational band and that the magnitude of this element is comparable with that between the γ-vibrational and ground-state bands. Arguments favoring and apparently refuting the interpretation of the 1322 keV, 0⁺ band as a “two-phonon γ-vibration” are presented.     

Neutron diffraction study of molybdenum dioxide

The magnetic properties of powdered, crystalline molybdenum dioxide have been studied by neutron diffraction at 293°K and 673°K. The results establish the absence of a permanent magnetic moment on the Mo(IV) ions in this compound and confirm that MoO₂ has a small temperature-independent magnetic susceptibility. This latter is considered to arise from Pauli paramagnetism of the collective electrons.     

Studies on tetraborane(8) carbonyl, B4H8·CO: its isomeric composition in the gas phase and in solution, and its reactions with alkenes

¹¹B NMR spectra of tetraborane(8) carbonyl, B₄H₈·CO 1, reveal a changeover in the distribution of isomers in going from toluene solution to the gas phase. Fortuitously the distribution is 60:40 in each case, but comparison with published electron diffraction data and ab initio/IGLO computations indicates that the CO group is disposed endo with respect to the B₄ `butterfly' framework in the predominant isomer in the gas phase, and exo in solution. The results also allow conclusions to be drawn about the geometries of other B₄H₈·L isomers on the basis of their reported proton NMR chemical shifts. Reactions of B₄H₈·CO with ethene and propene at ca. 30 bar yield products, R₄B₄H₄·CO (R=Et 2 or Pr³ 3), in which all four wingtip hydrogen atoms of the tetraborane carbonyl have been replaced by alkyl groups. Variable-temperature ¹¹B and ¹H NMR spectra of 2 and 3 reveal interesting fluxional behaviour.     

Analysis of long-lived isotopes by liquid scintillation spectrometry

Neutron production cross sections are reported for reactions leading to long-lived isotopes in fusion reactor materials. Pure elements and separated isotopes were irradiated with 14.6–14.8 MeV neutron fluences up to 10¹⁸ n/cm². Undesired activities were chemically separated and the long-lived activities were measured using both liquid scintillation and x-ray spectrometry. Results are presented for the reactions⁵⁶Fe(n,2n)⁵⁵Fe(2.73 y),⁶⁴Ni(n,2n)⁶³Ni(100 y),⁶³Cu(n,p)⁶³Ni, and⁶⁰Ni(n,2n)⁵⁹Ni(76,000 y).Work supported by the U.S. Department of Energy.     

The FeSe system. II. Mössbauer diffusional line-broadening studies of Fe1 + xSe2 (x ∼ 0.5, i.e., Fe∼3Se4)

Diffusional line broadening of the ⁵⁷Fe Mössbauer resonance has been observed in samples of Fe_{1 + x}Se₂ (x = 0.50 and 0.55) in the temperature range 820 to 980°K. The lineshapes could not be fitted to a single Lorentzian peak and indicated non-Lorentzian behavior. The lattice, which has the NiAsCdI₂ structure, contains jump pathways in one, two, and three dimensions, each of which is predicted to give a different line shape when the jump frequency approaches the mean life of the Mössbauer excited state (～100 nsec). The observed shapes were not consistent with only one-dimensional diffusion or only three-dimensional diffusion, but could be interpreted as arising from a mixture of several of the jump types.     

Synthesis of 2H-1,2-benzothiazine 1,1-dioxides via heteroannulation reactions of 2-iodobenzenesulfonamide with ketone enolates under S(RN)1 conditions

[Reaction: see text]. 2-iodobenzenesulfonamide (1a) underwent photostimulated S(RN)1 reactions in liquid NH3 with the potassium enolates derived from acetone, pinacolone, butanone, and 3-methyl-2-butanone to give fair to good yields of 2H-1,2-benzothiazine 1,1-dioxides 2. Reductive dehalogenation of 1a was found to predominate in photoinduced reactions of 1a with 3-pentanone, 2-methyl-3-pentanone, and 2,4-dimethyl-3-pentanone, the extent of reduction being proportional to the number of beta-hydrogen atoms present in the ketone enolate. Isotopic labeling studies with 2,4-dimethyl-3-pentanone-d14 (24) confirmed the major role of the beta-hydrogens in the reduction process. Reactions of 1a with cyclopentanone, cyclohexanone, and cyclooctanone enolates afforded new tricyclic benzothiazine derivatives 26-29. Attempts to extend the heteroannulation reaction to the preparation of 2H-1,2-benzothiazin-3(4H)-one 1,1-dioxides 3 (R = H, Ph) through reactions of 1a with tert-butyl acetate and ethyl phenylacetate enolates resulted only in hydrodehalogenation of 1a. However, oxazoline anion 30, a synthetic equivalent of ethyl phenylacetate, was successfully employed in an alternative S(RN)1-based synthesis of benzothiazine 3 (R = Ph).     

Etude par effet Mössbauer des composés de type “bronzes fluorés” MxFeF3 (M = K,Rb, Cs,NH4)

The hexagonal, tetragonal and pyrochlore-type nonstoichiometric iron fluorides M_xFeF₃ (M = K, Rb, Cs, NH₄) have been studied by Mössbauer spectroscopy over the temperature range 4.2 to 295 K. The magnetic transition temperatures have been determined. The ferrous and ferric ions remain in discrete oxidation states indicating the absence of charge hopping. The broadened lines of the spectra of the hexagonal and tetragonal phases are consistent with the disordering of Fe²⁺ and Fe³⁺ in the structure. By contrast, the narrow linewidths of the spectra of the pyrochlore-type phases characterize a structural ordering between the ferrous and ferric ions.