Multiexciton and Dephasing Processes in Semi-Conductor Quantum Dots

Lachlan McKimmie, Craig Lincoln

Semi-conductor nanocrystals (Quantum Dots) have excellent potential as the next generation of smart materials for a myriad of applications including fluorescence imaging of biological samples, solid-state laser systems, and photovoltaics for optical switching and power generation. Understanding the fundamental processes governing the optical properties of theses materials is essential for their continued development. Using the above techniques we aim to determine the effect of multi-exciton interactions and wavefunction delocalisation to enhance QDs quantum yield and efficiency as a laser gain medium.

Mechanism of Photoconversion in Fluorescent Proteins

Craig Lincoln, Lachlan McKimmie

The aim of this project is to continue the development of novel fluorescent proteins for use as fluorescent markers. In taking the next steps of development, a comprehensive characterisation program is proposed involving femtosecond laser spectroscopy and computational experiments to identify residues of importance to the function of fluorescent proteins. The continued development of fluorescent proteins with optimised fluorescent properties such as photoconversion (“Kindling”), production/quenching of reactive oxygen species and spectral tuning is paramount to the application of these proteins as fluorescent markers for microscopic techniques.

Forensic Applications of Fluorescence Lifetime Imaging Microscopy

Damian Bird

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Development of High-Signal-To-Noise Deep-UV Fluorescence Microscope

Craig Lincoln, Peter Wichta

We introduce a project to develop a high signal-to-noise confocal microscope capable of one- and two-photon excitation of native fluorescence for non-destructive in situ imaging of proteins. Current commercially available microscopes have low efficiency in the wavelength regions below 400 nm, where the amino acid residue tryptophan (Trp), responsible for most native fluorescence, absorbs (280 nm) and fluoresces (340-360 nm). In many cases, the low efficiency combined with the poor photostability of Trp prohibits the direct study of native proteins in situ, a problem that will be alleviated by the increased transmission and collection at theses wavelengths in our microscope.
The advantages of using the intrinsic fluorescence from Trp include avoiding the problems associated with tag molecules, namely the effects that such molecules may have on the surrounding environment and/or the conformational folding of the protein being studied. The fluorescence spectrum of the Trp has been shown to spectrally shift as a function of protein folding and the intensity to change when the protein binds to another molecule, thus allowing investigations of molecular activity and co-operativity.

Transdermal Drug Delivery - Characterisation Using Fluorescence Lifetime Imagaing Microscopy

Damian Bird

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Surface Science Studied Using Evanescent Wave Induced Fluorescence Microscopy

Andrew Rapson, Anna Mularski

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Nano-Assembly of Light Emitting Polymer Films

Xiaotao Hao, Nikko Chan, David Dunstan

Light emitting polymers are materials that belong to a class of polymers known as conjugated polymers, or also referred to as conducting polymers. These polymers have a backbone of conjugated bonds, which allows the molecules to transfer electrons in a manner similar to a semi-conducting material. The focus of this project is on fluorescent conjugated polymers, which are conjugated polymers capable of producing fluorescence and electroluminescence. Fluorescent conjugated polymers have a wide range of applications, such as for use in light emitting devices in the form of polymer light emitting diodes or flexible display screens, and in photovoltaic cells. Conjugated polymers have advantages over traditional semi-conducting materials due to ease of processing and desirable mechanical properties of polymers. It has been proposed that orientation and alignment of polymer molecules will increase the efficiency of fluorescence and improve the performance of devices made from these polymers. Tensile stretching has been identified as a simple and effective method of orienting polymer molecules in a bulk film, therefore experiments on how stretching affects polymer film blends containing fluorescent conjugated polymers were conducted. Single molecule techniques such as Confocal Microscopy and Near-field Scanning Optical Microscopy will be employed to further investigate the underlying photophysics of the conjugated polymers. The key objectives of this project are to understand the underlying photophysics of single molecules of fluorescent conjugated polymers using single molecule spectroscopy techniques, and to investigate processing methods to achieve light emitting thin films with molecular orientation.