Date of Award

Fall 2012

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Chemistry and Chemical Biology

Supervisor

Adam P. Hitchcock

Language

English

Committee Member

Andrew P. Knights, Harald D.H. Stöver

Abstract

Scanning transmission x-ray microscopes (STXM) focus monochromatic x-rays into an intense sub-30 nm diameter spot. Samples are then positioned at the focal plane and raster scanned through the spot while the transmitted x-rays are acquired to build up images at x-ray photon energies. In addition, x-ray absorption spectroscopy (XAS) can be performed by recording image sequences over a photon energy range of interest. STXMs excel at characterizing thin sections of inhomogeneous soft matter with their combination of high spatial (<30 nm) and photon energy (<0.1 eV) resolution. However, the overarching theme of this thesis is to apply the intense, tightly focused spot of x-rays to induce spatially resolved chemical and physical changes, and directly pattern materials, primarily thin polymer films. The irradiated areas are then investigated using several types of microscopy (scanning transmission x-ray, atomic force, scanning electron) and XAS. The experiments cover three broad areas: i) Nanofabrication; realization of the smallest possible feature sizes, and fabrication schemes unique to focused x-rays with applications including nanofluidics. ii) Radiation chemistry and physics; investigating the mechanisms of radiation-induced processes such as bond formation/loss, morphological change, carbon contamination, and temperature increase. iii) X-ray optics; the spatial distribution of x-rays at a focal plane can be recorded in a thin polymer film and later read out using an atomic force microscope. Applications include feedback for optics fabrication and enhanced image processing, the ultimate goal being increased spatial resolution.

McMaster University Library


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