Ronald S. Haines

Time-resolved infrared-ultraviolet double resonance studies of rotational relaxation in D2CO

Abstract Rotational relaxation of the ν4 = 1, J = 18, Ka = 11 state of D2CO is found to be faster than gas-kinetic and to involve multiple quantum changes in J within a single collision between D2CO molecules. The results conform to scaling laws based on |ΔJ| or the energy change |E| for the state-resolved molecule.

Effect of Modifying the Anion of an Ionic Liquid on the Outcome of an SN2 Process

The effect of a series of ionic liquids containing different anions (bis(trifluoromethanesulfonyl)imide, dicyanimide, hexafluorophosphate, tetrafluoroborate, and bromide) on the rate constant of a bimolecular substitution process was investigated. A general ionic liquid effect was noted, with increases in the rate constant observed in all ionic liquids used when compared with that in acetonitrile. Temperature-dependent kinetic data allowed calculation of activation parameters in each of the reaction mixtures considered; these parameters showed that the microscopic origins of the rate enhancements observed were not the same for all of the ionic liquids used, demonstrating the importance of the nature of the anion.

Raman intensities and cartesian polarizability derivatives

Cartesian polarizability derivatives are defined as derivatives of the molecular polarizability with respect to the displacement of an atom in a space-fixed axis system. These derivatives are used to describe the intensity of molecular vibrational and rotational Raman scattering. The number of independent derivatives is easily determined and is shown to equal the number of intensity parameters which may be obtained from experiment. The cartesian polarizability derivatives thus form a complete, minimal set of parameters for describing Raman intensities.

Rotationally resolved Raman-optical double resonance with fluorescence detection

A pulsed excitation sequence, consisting of coherent Raman pumping of a molecular rovibrational transition followed by rovibronic probing through visible laser-induced florescence, is used in Raman-optical double resonancestudies of D(2)CO. The experiments demonstrate enhanced sensitivity, with respect to conventional coherent Raman spectroscopy, and enable individual O- and P-branch Raman transitions to be distinguished with high specificity under effectively collision-free conditions.

On the determination of the relative signs of polarizability derivatives

Abstract Isotopic substitution which lowers the symmetry of a molecule mixes normal modes of different symmetry. Relative signs of the anisotropies of polarizability derivatives associated with such modes may be obtained from the intensity distribution in the vib-rotational Raman spectrum of the lower symmetry species. The application to methane is given and a comparison of theory and experiment for CH 2 D 2 is presented.

Ionic liquid solvents: the importance of microscopic interactions in predicting organic reaction outcomes

Abstract Ionic liquids are attractive alternatives to molecular solvents as they have many favourable physical properties and can produce different organic reaction outcomes compared to molecular solvents. Thus far, interactions between the ionic liquid components and specific sites (such as charged centres, lone pairs and π systems) on the reagents and transition state have been identified as affecting reaction outcome; a comprehensive understanding of these interactions is necessary to allow prediction of ionic liquid solvent effects. This manuscript summarises our recent progress in the development of a framework for predicting the effect of an ionic liquid solvent on the outcome of organic processes. There will be a particular focus on the importance of the different interactions between the ionic liquid components and the species along the reaction coordinate that are responsible for the changes in reaction outcome observed in the cases described.