Evidence for the Bφ decay mode of the ω(1670)

Backward production of ω(1670) is observed in the reactions K^?p→φ⁺φ^?ω⁰Λ⁰ and K^?p→φ⁺φ^?φ⁰φ⁰ for |U'_Λ|<1.0 GeV². The cross section for the ω(1670) →φ⁺φ^?ω⁰ decay mode is 1.90±0.35 μb for 8.25 GeV/c incident K^?. Evidence is presented for the importance of the sequential decay, ω(1670) → Bφ → ωφφ with a branching ratio ω(1670) → Bφ/all ω(1670) → ωφφ=1.0±_0.25^0.00.     

The Infrared Spectrum of C2D2: The Bending States up to v4+v5=2

The vibration-rotation spectrum of ¹³C₂D₂ has been recorded in the infrared region between 420 and 1100 cm⁻¹ with an effective resolution ranging from 0.004 to 0.006 cm⁻¹, and in the millimeter-wave region between 68 and 518 GHz. A total of about 1400 rovibrational transitions (66 of which have been measured in the millimeter-wave region) have been assigned to 8 bands with 15 l-vibrational components involving the bending states up to v_t=v₄+v₅=2. The ground state and nine vibrationally excited states have been characterized. All the measured transitions have been analyzed simultaneously by adopting a model Hamiltonian which takes into account the usual vibration and rotation l-type resonances, together with the Darling-Dennison coupling between the v₄=2 and v₅=2 bending states. The derived spectroscopic parameters reproduce the transition wavenumbers with a standard deviation of the fit of the order of the experimental uncertainty.     

A thermal neutron investigation of magnetic correlations in liquid oxygen

The neutron scattering cross section for liquid and gaseous oxygen is reported. Polarisation techniques are used to separate nuclear and magnetic contributions for the liquid phase. The profile for magnetic scattering indicates significant magnetic correlations in the liquid which are consistent with antiferromagnetic ordering in the condensed phase. The results are related to the magnetic structures of the various crystalline phases of oxygen.     

The structure factor for liquid nitrogen and liquid oxygen from neutron scattering studies

The structure factor, S(Q), has been measured for liquid nitrogen at 77 K and liquid oxygen at 84 K by neutron diffraction over a range of momentum transfer, Q, from 0·3 to 7·3 Å^-1. In the case of oxygen a correction for magnetic scattering has been included.

The liquid structure factor for nitrogen compares well with that obtained from X-ray diffraction measurements but there are significant discrepancies in the case of oxygen. These may be partially attributed to uncertainty in the form factor for paramagnetic scattering.

The data have been analysed in terms of several different models for the orientational correlation between neighbouring molecules. The results are particularly sensitive to uncertainties in the absolute normalization of the data, the inter-nuclear distance for the molecular structure and Placzek corrections; the effect of these errors is considered in detail. It is shown that some form of orientation correlation must exist but its precise nature could not be obtained from the present data.     

[1]Benzothieno[2,3-d]pyridazines V. Etude des Réactions de substitution des Benzothiéno[2,3-d]pyridazinethiones

The substitution and addition reactions of the 2H[1]benzothiéno[2,3-d]phyridazinethione-1 and the 3H[1]benzothiéno[2,3-d]pyridazinethione-4 gave N- or S-substituted derivatives whose structures were identified by 1R and NMR spectroscopy.     

[1]Benzothiéno [2,3-d]pyridazines—VI : Etude des réactions de cyclisation des hydrazinobenzothiénopyridazines

The 1- and 4-hydrazino[1]benzothiéno[2,3-d]pyridazines have been cyclised to form triazolobenzothienopyridazines, tetrazolobenzothienopyridazines and benzothienopyridazinotriazines. NMR study shows a tautomeric equilibrium in solution between tetrazolo [1,5-b][1]benzothiéno[3,2-d] pyridazine and 1- azido [1]benzothieno[2,3-d]pyridazine. Reactions of the benzothienopyridazinotriazones with hydrazine were studied.     

The structure of amorphous carbon tetrachloride by neutron diffraction

A vapour-deposited sample of amorphous CCl₄ at 10 K has been studied by neutron diffraction. The measured structure factor confirms that the basic molecular unit is retained in the amorphous phase and a form-factor fit to the high Q-value data gives a CCl bond length of (1.770±0.002) Å. The inter-molecular function, D_M(Q) shows more structure than for the liquid phase and transformation to a real-space distribution function confirms that this is due to a much stronger orientational correlation between adjacent molecules in the amorphous solid. The density is found to be (25±5)% higher than in the liquid and the structural properties can be well described using a reference interaction site model (RISM).     

Comparison of the absorption, emission, and resonance Raman spectra of 7-hydroxyquinoline and 8-bromo-7-hydroxyquinoline caged acetate

To better understand the deprotection reaction of the new promising phototrigger compound BHQ-OAc (8-bromo-7-hydroxyquinoline acetate), we present a detailed comparison of the UV-vis absorption, resonance Raman, and fluorescence spectra of BHQ-OAc with its parent compound 7-hydroxyquinoline in different solvents. The steady-state absorption and resonance Raman spectra provide fundamental information about the structure, properties, and population distribution of the different prototropic forms present under the different solvent conditions examined. The species present in the excited states that emit strongly were detected by fluorescence spectra. It is shown that the ground-state tautomerization process of BHQ-OAc is disfavored compared with that of 7-HQ in aqueous solutions. The observation of the tautomeric form of BHQ-OAc in neutral aqueous solutions demonstrates the occurrence of the excited-state proton-transfer process, which would be a competing process for the deprotection reaction of BHQ-OAc in aqueous solutions.