Physics Commons^™

Photothermal Deflection Spectroscopy Of Amorphous, Nanostructured And Nanocomposite Thin Films, Muhammad Shafiq Ahmed

Electronic Thesis and Dissertation Repository

The energy needs of the modern world are growing day by day, while sources of non-renewable fossil fuels are limited, so there is a need to efficiently use the existing resources and explore renewable energy sources. In order to harvest, store and efficiently utilize renewable energy, we need to explore new materials and improve the performance of existing ones. Among others, hydrogenated amorphous silicon (a-Si:H) with high optical absorption in the visible range of electromagnetic spectrum, is a low cost material for solar cells. But the efficiency of such solar cells is comparatively low because of intrinsic defects associated with …

Diffusionless Transition In Tricosane And Reversible Inhibition Of Calcium Oxalate Monohydrate: Two Studies Of Crystal Growth, Shailesh S. Nene

Electronic Thesis and Dissertation Repository

The process of crystal growth has been intensively studied, for both its academic interest and industrial importance. I report here two studies of crystal growth.

The normal alkanes are an interesting, both in terms of their intrinsic properties and because many biological materials contain hydrocarbon domains. The normal alkanes often exhibit complicated phase behaviour, with phase diagrams containing multiple solid phases. We report here a curious pattern of twinned domains seen in one phase of tricosane (C23H48), which we have studied by X-ray diffraction, as well as by optical and atomic force microscopy. This pattern is seen in the rotator …

Optimization Of Force Sensitivity In Q-Controlled Amplitude-Modulation Atomic Force Microscopy, Jongwoo Kim, Baekman Sung, Byung I. Kim, Wonho Jhe

Physics Faculty Publications and Presentations

We present control of force sensitivity in Q-controlled amplitude-modulation atomic force microscopy (AM-AFM) that is based on the high-Q quartz tuning-fork. It is found that the phase noise is identical to the amplitude noise divided by oscillation amplitude in AM-AFM. In particular, we observe that while Q-control does not compromise the signal-to-noise ratio, it enhances the detection sensitivity because the minimum detectable force gradient is inversely proportional to the effective quality factor for large bandwidths, which is due to reduction of frequency noise. This work demonstrates Q-control in AM-AFM is a useful technique for enhancement of …

Optically Induced Forces In Scanning Probe Microscopy, Dana Kohlgraf-Owens

Electronic Theses and Dissertations

The focus of this dissertation is the study of measuring light not by energy transfer as is done with a standard photodetector such as a photographic film or charged coupled device, but rather by the forces which the light exerts on matter. In this manner we are able to replace or complement standard photodetector-based light detection techniques. One key attribute of force detection is that it permits the measurement of light over a very large range of frequencies including those which are difficult to access with standard photodetectors, such as the far IR and THz. The dissertation addresses the specific …