No description available.

No description available.

Coherent anti-Stokes Raman scattering (CARS) microscopy has developed rapidly and is opening the door to new types of experiments. This work describes the development of new laser sources for CARS microscopy and their use for different applications. It is specifically focused on multimodal nonlinear optical microscopy—the simultaneous combination of different imaging techniques. This allows us to address a diverse range of applications, such as the study of biomaterials, fluid inclusions, atherosclerosis, hepatitis C infection in cells, and ice formation in cells. For these applications new laser sources are developed that allow for practical multimodal imaging. For example, it is shown that using a single Ti:sapphire oscillator with a photonic crystal fiber, it is possible to develop a versatile multimodal imaging system using optimally chirped laser pulses. This system can perform simultaneous two photon excited fluorescence, second harmonic generation, and CARS microscopy. The versatility of the system is further demonstrated by showing that it is possible to probe different Raman modes using CARS microscopy simply by changing a time delay between the excitation beams. Using optimally chirped pulses also enables further simplification of the laser system required by using a single fiber laser combined with nonlinear optical fibers to perform effective multimodal imaging. While these sources are useful for practical multimodal imaging, it is believed that for further improvements in CARS microscopy sensitivity, new excitation schemes are necessary. This has led to the design of a new, high power, extended cavity oscillator that should be capable of implementing new excitation schemes for CARS microscopy as well as other techniques. Our interest in multimodal imaging has led us to other areas of research as well. For example, a fiber-coupling scheme for signal collection in the forward direction is demonstrated that allows for fluorescence lifetime imaging without significant temporal distortion. Also highlighted is an imaging artifact that is unique to CARS microscopy that can alter image interpretation, especially when using multimodal imaging. By combining expertise in nonlinear optics, laser development, fiber optics, and microscopy, we have developed systems and techniques that will be of benefit for multimodal CARS microscopy. / Thesis (Ph.D, Physics, Engineering Physics and Astronomy) -- Queen's University, 2011-08-11 13:46:26.065

No description available.

There is no abstract available for this thesis. / Department of Physiology and Health Science

The Kelvin Probe Force Microscope is a type of scanning probe instrument that is used to discern the different work functions of a sample. A sharp probe at the end of a cantilever is lowered onto a substrate where electrostatic forces, caused by the difference in work function cause the cantilever to oscillate at the modulated frequency. Using this instrument, high resolution images can be obtained, mapping the surface electronic characteristics. However, developments of this instrument have generally been limited to obtaining higher resolution images as well as reducing noise in the output, limiting the widespread appeal of this expensive instrument. There exist many applications where extremely cheap, low footprint and easy-to-use Kelvin Probe Force Microscopes would be beneficial. In order to cheaply produce this microscope in batch, a post-processed CMOS-MEMS device is utilized. The polysilicon resistors act as a strain gauge such that a conventional optical system will not have to be employed. The ability to use integrated bimorph actuators on chip allow for movement of the cantilever without the employment of large piezoelectric stages with creep effects. Embedded electronics can be fabricated with the CMOS process alongside the MEMS device, allowing full integration of an on board amplifier and read out system. In general, a large table top system can be minimized onto the size of a <1 mm2 area, a microcontroller and a computer. In this work, a Kelvin Probe Force Microscope is designed, fabricated and validated. A MEMS device was designed following similar characteristics of a generic cantilever beam. The stiffness, length, resonant frequency, and other tip characteristics can be mimicked with careful design. The resultant designs were fabricated using a CMOS-MEMS process. In order to obtain a sharper tip with modified characteristics, various methods were employed; such as gallium-aluminum alloy tip formation as well as electroless plating onto the tip of the device. Finally, the resultant device is tested against a sample. It was seen that the MEMS device followed similar characteristics of the conventional microscope itself, validating the equations that define the method. Bimorph actuators were tested to show movement, allowing the integration of the cantilever with the XYZ-stage. Work function changes are observed while scanning different materials. It is shown throughout the course of this thesis, that a true Kelvin Probe Force Microscope can be designed, fabricated and validated using CMOS-MEMS technology.

No description available.

Many low dimensional structures arise from self-assembly when depositing metals on silicon surfaces, including both quantum dots and quantum wires. One class of these objects are rare earth silicide nanowires (RENW) grown on Si(001). In this dissertation, NW thermal stability, control of NW cross section, and associated surface reconstructions are studied by Scanning Tunneling Microscopy (STM). We test thulium and find for the first time that it forms NWs and these NWs are stable against prolonged annealing. We also find that the RENWs nucleate at 2×7 reconstruction domain boundaries. These results pave the way for precise control over NW size, placement, and integration with functional nanostructures and nanodevices.Another type of self-assembled NWs on Si(001) are insulating CaF2 NWs. As an ideal model system for epitaxial growth of an insulator on a semiconductor surface, CaF2 offers unique properties such as simple structure, good lattice match to silicon and congruent evaporation. In this thesis the growth behavior of CaF2 on the Si(001) surface is investigated. At low coverages CaF2 molecules randomly locate on Si(001). Features observed at this stage are explained in terms of dissociated fragments of CaF2 terminating the dangling bonds of Si dimers. Etching is observed after surface is saturated by these features with a 2×1 periodicity. A 2×n phase, grown at 750°C, suggests the dissociation of CaF2, as proved by the simulation of LEED patterns. A c(4×4) phase is observed from 0.5ML to about 1ML with deposition temperature from 600oC to 700oC. At the highest CaF2 deposition coverages studied, a stripe phase and CaF2 NWs are observed by a combination of STM, AFM and SEM. The results provide a significant expansion in the knowledge of CaF2 on Si(001). The common thread that links all these studies is the extent to which nanostructures can be controlled by careful growth conditions, not just by substrate temperature and the amount of material deposited, but also by timing of post-deposition annealing, etc. The grown nanostructures are metastable and result from a balance of energetic considerations and kinetics.

Many low dimensional structures arise from self-assembly when depositing metals on silicon surfaces, including both quantum dots and quantum wires. One class of these objects are rare earth silicide nanowires (RENW) grown on Si(001). In this dissertation, NW thermal stability, control of NW cross section, and associated surface reconstructions are studied by Scanning Tunneling Microscopy (STM). We test thulium and find for the first time that it forms NWs and these NWs are stable against prolonged annealing. We also find that the RENWs nucleate at 2×7 reconstruction domain boundaries. These results pave the way for precise control over NW size, placement, and integration with functional nanostructures and nanodevices.Another type of self-assembled NWs on Si(001) are insulating CaF2 NWs. As an ideal model system for epitaxial growth of an insulator on a semiconductor surface, CaF2 offers unique properties such as simple structure, good lattice match to silicon and congruent evaporation. In this thesis the growth behavior of CaF2 on the Si(001) surface is investigated. At low coverages CaF2 molecules randomly locate on Si(001). Features observed at this stage are explained in terms of dissociated fragments of CaF2 terminating the dangling bonds of Si dimers. Etching is observed after surface is saturated by these features with a 2×1 periodicity. A 2×n phase, grown at 750°C, suggests the dissociation of CaF2, as proved by the simulation of LEED patterns. A c(4×4) phase is observed from 0.5ML to about 1ML with deposition temperature from 600oC to 700oC. At the highest CaF2 deposition coverages studied, a stripe phase and CaF2 NWs are observed by a combination of STM, AFM and SEM. The results provide a significant expansion in the knowledge of CaF2 on Si(001). The common thread that links all these studies is the extent to which nanostructures can be controlled by careful growth conditions, not just by substrate temperature and the amount of material deposited, but also by timing of post-deposition annealing, etc. The grown nanostructures are metastable and result from a balance of energetic considerations and kinetics.

Thesis (PhD) -- University of South Australia, 1998