Perturbed Morse oscillator calculations of vibrational effects on quadrupole coupling in alkali halides

Formulas are obtained for the variation of the quadrupole coupling constant with vibrational state of an ionic diatomic molecule, using the pertubed Morse oscillator formalism. Results are apllied to NaF, KF, RbF, CsF and KCI, and compared with measured values. Systematic discrepancies are noted, which for the alkali fluorides increase with the atomic number of the alkali metal. Possible explanations include a variation of ionicity with vibrational states and a departure from 1/r³ dependencies of the electric field gradient. Calculations of dependencies of eQq on molecular rotation are also presented.     

A synthetic entry into the 2- and 3-substituted-methyl 2,3-dihydro-1,4-benzoxazine series

Nmr spectroscopy has been used to demonstrate that the reported preparation of supposed 3-bromomethyl-2,3-dihydro-1,4-benzoxazine ( 3 ) is in error, the product of the reaction being in reality a monocyclic compound, 4 . An alternative entry to the 3-substituted series is described in the synthesis of the 3-hydroxymethyl derivative, 10 , the structure of which was established by nmr and mass spectroscopy. The previous assignment of structure to 2-carbethoxy-2,3-dihydro-1,4-benzoxazine, prepared by an ambiguous route, and to compounds derived from this ester, is shown to be correct.     

The real part of the forward proton proton scattering amplitude measured at the CERN intersecting storage rings

The real part of the proton proton elastic scattering amplitude has been determined from its interference with the Coulomb amplitude at total centre-of-mass energies up to 62 GeV. The observed steady increase of ? with energy indicates that the total proton proton cross section continues to increase well beyond this energy.     

The Use of a Modified Resin for Studying the Internal Structure of Microcrystalline Cellulose Particles

The use of a modified resin which allows the study of the internal structure of microcrystalline cellulose is described. Electron probe microanalysis and elemental X-ray mapping suggest that it is possible to identify cellulose within cross-sectioned microcrystalline cellulose particles.     

Trends in Radiation Polymerization

Previously it was generally assumed that high energy radiation could only initiate radical polymerization in solutions of monomers. However, examples of radiation-induced polymerization have recently become known that proceed via an ionic mechanism. Thus, solutions of a monomer can be polymerized ionically, preferably in the presence of a solid, at low temperatures. Suprisingly, this may also be accomplished with ultra-pure, mainly anhydrous systems, even at room temperature. The nature of the ions has not yet been fully elucidated.     

Vibrational spectra and crystal structure of the di‐amino acid peptide cyclo(L‐Met‐L‐Met): comparison of experimental data and DFT calculations

Experimental Raman and FT‐IR spectra of solid‐state non‐deuterated and N‐deuterated samples of cyclo(L ‐Met‐L ‐Met) are reported and discussed. The Raman and FT‐IR results show characteristic amide I vibrations (Raman: 1649 cm⁻¹, infrared: 1675 cm⁻¹) for molecules exhibiting a cis amide conformation. A Raman band, assigned to the cis amide II vibrational mode, is observed at ∼1493 cm⁻¹ but no IR band is observed in this region. Cyclo(L ‐Met‐L ‐Met) crystallises in the triclinic space group P1 with one molecule per unit cell. The overall shape of the diketopiperazine (DKP) ring displays a (slightly distorted) boat conformation. The crystal packing employs two strong hydrogen bonds, which traverse the entire crystal via translational repeats. B3‐LYP/cc‐pVDZ calculations of the structure of the molecule predict a boat conformation for the DKP ring, in agreement with the experimentally determined X‐ray structure. Copyright © 2009 John Wiley & Sons, Ltd.     

Superfluidity and dimerization in a multilayered system of fermionic polar molecules

We consider a layered system of fermionic molecules with permanent dipole moments aligned perpendicular to the layers by an external field. The dipole interactions between fermions in adjacent layers are attractive and induce interlayer pairing. Because of the competition for pairing among adjacent layers, the mean-field ground state of the layered system is a dimerized superfluid, with pairing only between every other layer. We construct an effective Ising-XY lattice model that describes the interplay between dimerization and superfluid phase fluctuations. In addition to the dimerized superfluid ground state, and high-temperature normal state, at intermediate temperature, we find an unusual dimerized "pseudogap" state with only short-range phase coherence. We propose light-scattering experiments to detect dimerization.