The theory of beta-radioactivity has been developed for a linear combination of the five usual forms of interaction and the resulting modifications to the energy distribution of the emitted radiation have been determined. The linear combination has been restricted in such a way that those explanations of beta spectra, allowed and forbidden, which have already been established with a particular form of the interaction, remain valid. A critical examination of the beta spectra of P32, Tc99, Sn125, Tm170, Tl204 and Rae, so far unexplained, has been carried out, making reasonable assumptions about spin and parity changes. On the basis of this discussion it is concluded that the interaction can only be a mixture of vector and tensor forms. Furthermore, the arbitrariness in the theoretical predictions has been reduced for two nuclei by evaluation of the nuclear matrix elements involved, using a simple model of the nucleus. By comparing these predictions with experiment an attempt has been made to determine the actual form of the interaction. The conclusion is that the interaction is a mixture of vector and tensor forms in the approximate ratio of two to one.

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Data for the physical properties of Room Temperature Ionic Liquids (RTILs) as a function of chemical composition is limited due to the expense and difficulty of producing large volumes of pure samples for characterization. RTILs comprise solely of ions and are liquid at room temperature. These are becoming of increasing interest for an extensive range of applications. This thesis looks at developing small scale characterization processes to find low cost and efficient methods for processing smaller sample volumes. Quartz crystal impedance analysis has been used to assess whether room temperature ionic liquids behave in a Newtonian manner to determine the values of their square root viscosity-density product using small volumes. Values are compared to traditional viscometer and densitometer measurements. A range of harmonics were studied for a 5 MHz fundamental crystal. The frequency shift of the third harmonic was found to provide the closest agreement between the two measurement methods with a limit seen at a square root viscosity-density product value of approximately 18 kg m⁻² s⁻⁰.⁵. Further characterisation of the liquid was performed to separate values of density and viscosity using dual Quartz Crystal Microbalance (QCM) with fabricated surface features on one QCM; this required a total sample volume of only 240 L. Values were corroborated with standard measurement techniques demonstrating good agreement. A QCM was then incorporated into a microfluidic glass chip system to measure the square root of the viscosity-density product of RTILs. The QCM covers a central recess on the glass chip, with a seal formed by tightly clamping from above outside the sensing region. The change in resonant frequency of an 8 MHz QCM operating on the 3rd harmonic was shown to allow determination of the square root viscosity-density product of RTILs to a maximum limit of square root viscosity-density product of approximately 10 kg m⁻² s⁻⁰.⁵. This microfluidic technique reduced the sample size needed for characterisation from 1.5 ml to only 30 μL and allowed the measurement to be made in an enclosed system reducing the risk of water contamination. In the final part of this work surface acoustic wave devices were studied. The most promising device, a Shear Horizontal Surface Acoustic Wave (SH-SAW) device with silicon dioxide guiding layer, provided good correlation between phase, insertion loss and the square root viscosity-density product. A maximum square root viscosity-density product limit was observed at approximately 10 kg m⁻² s⁻⁰.⁵ at which point the acoustic response becomes too damped for accurate results to be determined. This work provides a basis for further miniaturisation and characterisation which could develop a surface acoustic wave device based system for high throughput microfluidic characterisation of many properties of ionic liquids within a single chip.