Studies of negative ions formed by low energy electron impact

In this thesis the processes responsible for the formation of negative ions by the interaction of low energy electrons (0 to 15eV) with molecules in the gas phase have been investigated. Particular attention has been paid to the processes known as associative resonance capture and dissociative resonance capture. For a molecule AB, associative resonance capture is described by the equation AB + e → AB⁻, where the metastable molecular negative ion AB⁻ is formed by the capture of slow electrons. Dissociative resonance capture, described by the equation AB⁻ → A⁻ + B, results in the formation of a stable negative ion and can occur throughout the energy range studied. A historical review of the theoretical approach to electron-attachment is followed by detailed accounts of the most recent theoretical treatments of associative and dissociative resonance capture. The time-of-flight mass spectrometer used for this study has been described in some detail as have the experimental procedures developed. The various devices used to overcome the problems created by the broad electron energy distribution, which is due to the use of thermionically emitted electron beams, have been critically reviewed and the analytical deconvolution procedure adopted in this study has been described in detail. Autodetachment lifetimes and capture cross-sections for the associative attachment of electrons by several groups of organic and inorganic molecules have been measured and comparisons made with the predictions of the statistical theory for associative electron capture. Attempts to calculate electron affinities from this theory, using the lifetimes and cross -sections measured, met with some success for simple molecules and enabled conclusions to be made concerning the adequacy and limitations of the theoretical treatment. From studies of the electron energy dependence of negative ion formation for several groups of inorganic and organic molecules, various ionisation processes have been identified. Deconvolution of the ionisation curves has enabled accurate appearance potential data to be determined and, in many cases, allowed bond dissociation energies, electron affinities and heats of formation of various species to be evaluated

Signal specific electric potential sensors for operation in noisy environments

Limitations on the performance of electric potential sensors are due to saturation caused by environmental electromagnetic noise. The work described involves tailoring the response of the sensors to reject the main components of the noise, thereby enhancing both the effective dynamic range and signal to noise. We show that by using real-time analogue signal processing it is possible to detect a human heartbeat at a distance of 40 cm from the front of a subject in an unshielded laboratory. This result has significant implications both for security sensing and biometric measurements in addition to the more obvious safety related applications

A New Solution for the Dispersive Element in Astronomical Spectrographs

We present a new solution for the dispersive element in astronomical spectrographs that, in many cases, can provide an upgrade path to enhance the spectral resolution of existing moderate-resolution reflection-grating spectrographs. We demonstrate that in the case of LRIS-R at the Keck 1 Telescope, a spectral resolution of 18,000 can be achieved with reasonable throughput under good seeing conditions

The use of laptop computers in programming lectures

This research explores the effect of the use of laptop computers on students&rsquo; learning experiences during lectures. Our methodology involves embedding laptops with visualization software as a learning aid during lectures. We then employ a framework of seven principles of good practice in higher education to evaluate the impact of the use of laptop computers on the learning experience of computer programming students. Overall, we found that students were highly motivated and supportive of this innovative use of laptop computers with lectures.<br /

R v Mika: An investigation into the Court of Appeal’s neglect of s 27 of the Sentencing Act 2002

The Court of Appeal in the case of R v Mika failed to engage with section 27 of the Sentencing Act 2002 in dismissing Mr Mika’s appeal against his sentence. In both the High Court and Court of Appeal the focus was on Mr Mika’s argument for a discount of 10 per cent to be applied to his sentence to reflect his Māori heritage and associated social disadvantages. Section 27 of the Sentencing Act would allow a court to take into account cultural information regarding Maori offenders’ backgrounds and the systemic disadvantages stemming from this. In dismissing Mika’s appeal, the Court erred in not considering the clear signals from Parliament that the judiciary were to take into account Maori offenders’ backgrounds at the sentencing stage through s 27 in an effort to fit appropriate sentences to Maori offenders. Recent developments in Canada have seen the Canadian judiciary recognise their role in the over-representation of Aboriginal people in the Canadian prison population. The New Zealand judiciary can take lessons from the willingness of the Canadian judiciary to take cultural information into account at sentencing