A study of the spinel materials LiTi2O4 and Li43Ti53O4 by photoelectron spectroscopy

HeI-excited valence-band ultraviolet photoelectron spectra and MgKα-excited Ti-2p X-ray photoelectron spectra are reported for the spinel materials LiTi₂O₄ and $\text{Li}{}_{\mathrm{<mtext>4</mtext><mtext>3</mtext>}}\text{Ti}{}_{\mathrm{<mtext>5</mtext><mtext>3</mtext>}}\text{O}{}_4$. The presence of a Fermi edge in the ultraviolet photoelectron spectrum of LiTi₂O₄ confirms the metallic nature of this material, although the measured density of states at the Fermi energy is much lower than that expected from an independent-electron interpretation of the magnetic susceptibility. This difference is attributed to a strong interaction of the conduction electrons with the lattice vibrations. The localization of conduction electrons that occurs in the final state in the Ti-2p X-ray photoelectron spectrum of LiTi₂O₄ is attributed to a Coulomb interaction with a core hole.     

Studies of the reactions of Br(2P32) and Br(2P12) atoms with CH3F

The photobromination of methyl fluoride at low pressures has been studied experimentally. Bromine atoms in the ground (²P_{$\text{3}\text{2}$}) and excit     

Electronic-to-vibrational energy transfer from Br (42P12 to HF

Room temperature experiments have measured the rate of electronic-to-vibrational energy transfer between spin—orbit excited Br(4²P_{$\text{1}\text{2}$}) and HF. The Br^* + HF quenching rate is very fast, (1.1 ± 0.2) × 10⁶ s^?1 torr^?1, due to a near resonance between the spin—orbit splitting and the vibrational spacing. The majority of the Br^* spin—orbit energy goes directly into HF vibration.     

Far-infrared laser magnetic resonance spectrum of SeD (X2Π32)

Far-infrared laser magnetic resonance (LMR) spectra of SeD have been detected at 513 μm using a formic acid laser, and assigned to Zeeman components of the J = $\text{3}\text{2}$ → $\text{5}\text{2}$ transition in the six isotopic forms ^{82,80,78,77,76,74}SeD. Analysis yields the following B_o constants (cm^?1): ⁸²SeD 3.96047, ⁸⁰SeD 3.96284, ⁷⁸SeD 3.96532, ⁷⁷SeD 3.96657, ⁷⁶SeD 3.96793 and ⁷⁴SeD 3.97066. These values, combined with B_o for ⁸⁰SeH from 5.6μm LMR, yield r_e = 0.14634 nm for SeD.     

Kinetic spectroscopy in the far vacuum ultraviolet. Part I: Detection of (2p5) 2P32,12 fluorine atoms using atomic resonance spectrometry in the wavelength range 95–98 nm

A new experimental system for atomic resonance spectrometry at λ < 105 nm in a discharge-flow system is described. The spectrum of a fluorine resonance lamp has been studied, and possible precursors for the 2p⁴ 3s excited F atoms formed are suggested. Ground state (2p⁵²P_{$\text{3}\text{2}$}) and J-excited ²P_{$\text{1}\text{2}$} F atoms have been detected for the first time in resonance absorption and fluorescence using the first resonance transitions with wavelengths between 95.2 and 97.8 nm. Preliminary measurements (using both ⁴P-²P and ²P-²P lines) of the variations with concentration of absorption intensity by ground state F ²P_{$\text{3}\text{2}$} and by J-excited F ²P_{$\text{1}\text{2}$} atoms are reported; F atom concentrations were measured using a titration method based on the rapid reaction, F + Cl₂ → FCl + Cl.     

Emission spectra of the noble-gas halides: the B12A12 system

The B$\text{1}\text{2}$—A$\text{1}\text{2}$ transition has been detected in the emission spectra of ArBr, KrBr, Krl and XeI at low pressure. Comparison with the well-known /ldB–X” continua implies that, in many cases, the latter is heavily overlapped by C$\text{3}\text{2}$—A$\text{3}\text{2}$ emission.     

ESR studies on the reactions of sulphite radical anion,SO3.̄−, with nitroalkane compounds in aqueous solutions

The reactions of the sulphite radical anion, SO₃^{$\text{.}\text{?}$?} (generated from the Ti³⁺-H₂O₂-Na₂SO₃ system at pH 9), in aqueous solutions with some nitroalkane compounds were investigated by using a rapid-mixing flow technique coupled with electron spin resonance (ESR) which can detect the radicals having a lifetime of 5–100 ms. The SO₃^{$\text{.}\text{?}$?} radical added to the double bond of CN in the nitroalkane aci-anions which are the main form of nitroalkanes in aqueous alkaline solutions. From the observed hyperfine splitting constants of the SO₃^{$\text{.}\text{?}$?} adducts of nitroalkane aci-anions, the preferred conformation of the adducts was deduced.     

Wavelength dependence of the I(52P12,32) branching ratio from ICN Ã state photolysis

Quantum yields for the production of I(5²P$\text{1}\text{2}$) atoms from the photolysis of ICN in the à state continuum are presented as a function of wavelength. Evidence is presented for the existence of at least three electronic states giving rise to the absorption spectra. Primary photophysical processes involved in the dissociation of ICN are discussed.     

The spin 32 state (?) in six-coordinate iron (III). A Mössbauer and EPR investigation

Tris-(4-morpholinecarbodithioato-S,S′) iron (III) (FeM) and its dichloromethane solvate, (FeM·CH₂Cl₂), have been prepared and their temperature-dependent Mössbauer and EPR spectra have been determined at temperatures between liquid nitrogen and ambient. The Mössbauer spectra of FeM·CH₂Cl₂ differ considerably from that of FeM and is interpreted in terms of a four-line spectrum at 77 K. The EPR spectra of the two complexes indicate that the lower spin state of FeM·CH₂Cl₂ populates much more rapidly in the temperature range studied (100–300 K) than does FeM. These results support the postulation of an S = $\text{5}\text{2}$ ? S = $\text{1}\text{2}$ spin-equilibrium for FeM and a corresponding S = $\text{5}\text{2}$ ? S = $\text{3}\text{2}$ equilibrium for FeM·CH₂Cl₂.     

Behavior of p-dimethylamino-α-bormostyrene and its dimer in dioxane-water

Monomeric $\text{p}$-dimethylamino-$\text{α}$-bromostyrene undergoes S_Nl increasingly slowly in 60 to 91% dioxane. Reaction is catalyzed by HClO₄, NaOH and NaClO₄. Dimer 11 reverts to monomer I in 91% dioxane. There is only a small solvent effect on the solvolysis rate of II.     

T−12-law of dc conductivity 1N Langmuir films

Measurements of dc conductivity of Cd-stearate multilayer films below room tenperature down to liquid nitrogen temperature have revealed the temperature dependence σ = σ₀ exp(?AT^{?$\text{1}\text{2}$}). This relation, together with the values of σ₀ and A, confirms the theoretical predictions for hopping conduction in a multilayer system associated with interface states.     

Solvolytic behavior of p-dimethylamino-α-bromostyrene in water solutions

Nmr and UV studies show that $\text{p}$-dimethylamino-$\text{α}$-bromostyrene, I, undergoes S_Nl reaction in H₂O and HClO₄ (^kS_Nl = 6 × 10^?1sec.^?1 at 25°). The vinyl cation has an extraordinary selectivity for capture by aromatic amines relative to H₂O, including I itself to give the dimer II.     

Steroidal antifeedants from the dorid nudibranch Aldisasanguineacooperi

Two steroids, 3-oxo-chol-4-ene-24-oic acid ($\text{2}$) andi ts unsaturated analog $\text{4}$ have been isolated from the dorid nudibranch $\text{Aldisa}$$\text{sanguinea}$$\text{cooperi}$, and the acid $\text{2}$ has been shown to have antifeedant properties.     

Total synthesis of (+--oudemansin

($\text{+}\text{-}$)-Oudemansin has been synthesized starting from $\text{trans}$-cinnamaldehyde by a route involving the stereoselective Zn(BH₄)₂ reduction of β-keto ester.     

Collisional deactivation of laser-excited Br*(2P12) atoms with halogen and interhalogen molecules

Deactivation rates of spin-orbit excited Br*(²P_{$\text{1}\text{2}$}) atoms by halogens I₂, Br₂, and Cl₂ and interhalogens IBr, ICl and BrCl have been measured by laser-excited, time-resolved infrared emission techniques. The results are effectively explained in terms of a collision complex formation model.     

Four novel C28 sterols from lobophytum depressum

Four novel polyoxygenated C₂₈-sterols have been identified from the soft coral $\text{L. depressum}$ (the Gulf of Eilat, the Red Sea): the 22,28-lactol of 24-methylcholest-5-en-3β,22(R),25-triol-28-al ($\text{1}$), 24-methylcholest-5-en-3β,22(R),25,28-tetraol($\text{2}$) and the corresponding 5,6β-epoxides ($\text{3}$ and $\text{4}$).     

Alkylation of tricarbonylcyclohexadienyliron salts (1) with lithium alkyls

The salts $\text{1}$ (Y=H, OMe, Me) react with RLi(R=Me, n-Bu, i-Pr, t-Bu) in CH₂Cl₂ at low temperature to give $\text{2}$ and $\text{3}$ in excellent yields. Nucleophilic addition at the 1-position of $\text{1}$ (Y=OMe) has been observed for the first time.     

Synthesis of N-benzoyl L- and D-2,3,6-trideoxy-3-aminoxylo-hexose from non-carbohydrate precursors

The enantiomeric alcohols ($\text{2}$) and ($\text{11}$), obtained from (2$\text{R}$,3$\text{R}$) tartaric acid and, respectively, $\text{L}$-threonine, have been used to construct the C₆, enantiomeric deoxy amino sugar derivatives ($\text{7}$) and ($\text{12}$)     

Synthesis of the enantiomeric forms of cis and trans 1-benzyloxy-2,3-epoxy butane and of (3S,4S) 4-methyl-3-heptanol

The C₄erythro and threo diols (7) and (8) are converted either into the chiral epoxides (13) and (15) or into the enantiomers (14) and (16); the epoxide (13) is used as chiral synthon for the preparation of (3$\text{S}$,4$\text{S}$) 4-methyl-3-heptanol (21).     

The unexpected intramolecular C-arylation of 2-0-benzylated cyclic sugar derivatives: a useful 1,2-cis-C-glycosylation reaction

Upon treatment with tin(IV) chloride, perbenzylated glycofuranosyl acetates such as 3 or 6 undergo an unusual, intramolecular α-$\text{C}$-arylation resulting from the internal Friedel-Crafts alkylation of the 2-$\text{O}$-benzyl substituent.