Radiation-grafted alkaline anion-exchange membranes (AAEM) containing pendent groups with either benzyltrimethylammonium (BTM) or benzylmethylimidazolium (BMI) functionality were successfully synthesised from the same base membrane and with identical ion-exchange capacities. The conductivity of the new BMI-AAEM is comparable to the BTM-benchmark AAEM. The fuel cell performance obtained with the BMI-AAEM was, however, significantly poorer due to in situ AAEM degradation. FT-Raman spectroscopic studies on the stability of the two head-groups at 60 C in aqueous potassium hydroxide (1 mol dm À3) indicates that the BMI-group is intrinsically less chemically stable in strongly alkaline conditions compared to the BTM-benchmark head-group. However, the stabilities of both head-groups are improved when treated at 60 C in lower pH aqueous carbonate and bicarbonate solutions (1 mol dm À3). Contrary to a portion of the prior literature, there appears to be no real advantage in using anion-exchange polymer electrolytes containing pendent imidazolium groups in highly alkaline systems.

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Changes in protein secondary structure and conformation of ovalbumin and beta-lactoglobulin (15% protein w/w) were investigated by Fourier transform Raman spectroscopy and self-deconvolution. The amounts of alpha-helix, beta-sheets, random coil, and beta-turns in native beta-lactoglobulin were 15, 54, 6, and 25%, respectively, and those for ovalbumin (41, 34, 13, and 12%) compared well with published values obtained by X-ray crystallography. The proteins were heated at 90 degrees C for 30 min and high-pressure-treated at 600 MPa for 20 min. Heating increased beta-sheet structures in both proteins at the expense of alpha-helix; for beta-lactoglobulin beta-sheet structures increased from 54 to 70% and for ovalbumin, from 34 to 54%. Random coil increased from 6% in the native protein to 30% in high-pressure-treated beta-lactoglobulin. However, for ovalbumin, the contribution from beta-turns doubled in high-pressure-treated samples, with little change in random coil. Further examination of the deconvoluted amide I band in heated samples revealed several component bands. Bands at 1626 and 1682 cm(-1) for ovalbumin and at 1625 and 1680 cm(-1) for beta-lactoglobulin were observed and are associated with aggregated, intermolecular beta-sheet (beta-aggregation), indicative of heat denaturation. The band seen at 1632-1640 cm(-1) corresponded to intramolecular beta-sheet structures, whereas the band at 1625 cm(-1) is associated with exposed beta-sheets (for example, beta-strands with strong hydrogen bonding that are not part of the core of beta-sheets). In high-pressure-treated samples bands were also observed at 1628 and 1680 cm(-1) for ovalbumin and at 1626 and 1684 cm(-1) for beta-lactoglobulin, suggesting involvement of beta-sheet structures in protein aggregation. Raman bands were observed at 1665-1670 cm(-1) for ovalbumin and at 1663-1675 cm(-1) for beta-lactoglobulin due to random coil structures. The bands at 1650-1660 cm(-1) due to alpha-helices were observed in both heated and high-pressure-treated samples. In addition, in heated samples of both ovalbumin and beta-lactoglobulin, peak intensity increased for beta-sheet in the amide III region, 980-990 cm(-1), and decreased for helix structures (900-960 cm(-1)). In contrast, there was no peak at 1240 cm(-1) (amide III beta-sheet structures) in either high-pressure-treated ovalbumin or beta-lactoglobulin, suggesting that high-pressure denaturation at 600 MPa for 20 min is less extensive than heat denaturation at 90 degrees C for 30 min.

Lysozyme (25% in D2O, corn oil, and their emulsions (10% w/w oil/D2O solution) were examined by Fourier transform Raman spectroscopy. Emulsions showed three layers, namely, top oil, middle cream, and bottom aqueous layers. Raman spectral analysis revealed hydrophobic interactions involving both protein and lipid components. Compared to lysozyme in D2O, the difference spectrum obtained after subtraction of oil from the cream layer spectrum showed reduced intensity of tryptophan bands at 760, 1013, 1340, and 1360 cm(-)(1), reduced intensity ratio of the tyrosine doublet at 850 and 830 cm(-)(1), and increased intensity of the C-H bending band at 1455 cm(-)(1). Compared to corn oil, the difference spectrum after subtraction of lysozyme from the cream layer spectrum indicated decreased intensity at 2855 cm(-)(1) (lipid CH(2) symmetric stretch) and 3011 cm(-)(1) (unsaturated fatty acid hydrocarbon chain =C-H stretch) and a higher intensity ratio of the C-H stretching band at 2900 cm(-)(1) to bands at 2885 and 2933 cm(-)(1). Spectra of the top and bottom layers resembled corn oil and lysozyme, respectively, except for changes in the D2O band. Raman spectroscopy can be used to detect structural changes in proteins, lipids, and D2O due to protein-lipid interactions.

The present work has provided a complete set of assignments for the vibrational spectrum of Rb(2)PtH(6) and Rb(2)PtD(6). To confirm the assignments, a periodic density functional theory (DFT) code has been applied to the analysis of the inelastic neutron scattering (INS) spectrum of an ionic material for the first time. The work has also provided an explanation for the unusual infrared spectrum of the potassium salt. The most significant aspect of the work is the use of the momentum transfer information provided by an INS chopper spectrometer. The straightforward method employed for the analysis of the data is applicable to any molecular system (organic or inorganic) and demonstrates the potential of these instruments for chemistry. Periodic DFT was also used to study the other A(2)PtH(6) (A = alkali metal) including, the at present, unknown Li salt, which is found to be stable. The DFT studies have also highlighted the crucial role of the cation in removing charge from the transition metal and "hydride" ligand. It is suggested that this is a general occurrence.

We have studied the Raman spectrum of β-carotene using excitation wavelengths from visible (514.5 nm) to near-infrared (1064 nm). Qualitatively, the spectrum appears independent of the choice of excitation wavelength, although this is not true in detail; in particular, the ratio of the intensities of the νC-C and νC=C fundamentals to their overtones and combinations varies with the excitation wavelength. The inelastic neutron scattering spectrum shows no evidence for unusual dynamics in this system, and the UV/vis/NIR spectrum shows that there are no allowed electronic transitions from the ground state beyond ∼700 nm. These observations provide strong evidence for the existence of a different mechanism for the enhancement of the bands. Indirect evidence suggests that, with these longer excitation wavelengths, the intensities of the νC-C and νC=C peaks are at least two orders of magnitude smaller than those from resonance enhancement with the use of excitation into the visible absorption bands. The implications for the characterization of polyenes in polymers are discussed.

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In this paper we exploit the complementarity of inelastic neutron scattering (INS), infrared and Raman spectroscopies with ab initio calculations to generate an updated assignment of the vibrational modes of C(60). We have carried out periodic-DFT calculations of the high temperature face centred cubic phase modelled as the standard structure and also of the low temperature simple cubic phase, the latter for the first time. Our assignment differs from all previous work, however, it is the only one that is able to successfully reproduce the INS spectrum in terms of both transition energies and intensities. In addition to the INS spectrum we are also able to quantitatively simulate the major features of the infrared and Raman spectra in the high temperature phase and the infrared spectrum in the low temperature phase.