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Written Comprehensive Examination for Physics Graduate Students

Wriiten comprehensive exam

Three novel strategies for the structurally identification of nanocrystals in a Transmission Electron Microscope (TEM) are presented. Either a single High-Resolution Transmission Electron Microscopy (HRTEM) image or a single Precession Electron Diffractogram (PED) may be utilized. The structural identification information is in both cases collected from individual nanocrystals. PEDs from fine-grained crystal powders may also be used.

Structured materials which allow nanoscale control of light are necessary for achieving compact, integrated photonic devices. Surface plasmon polaritons, coupled modes of free electron oscillations and photons, are low dimensional excitations, strongly confined at metal-dielectric interfaces. While the size of standard optical components is limited by the wave diffraction limit, these essentially two-dimensional waves may be confined to nanoscale dimensions much smaller than optical wavelengths.

Intrinsic changes in glass due to temperature may be detected by comparing the Stokes and Anti-Stokes Raman Back Scatter. Employed along a fiber optic, one may in this way measure temperature along distances >10,000 m with 1 m resolution. This can then be used to make multi-scale observations of complex environmental processes. We will present examples of double diffuse turbulent structures in deep mine shafts, lake dynamics, and rivers.