Spatial and wavenumber resolution of Doppler reflectometry

Spatial and Wavenumber Resolution of Doppler Reflectometry

Spatial Wavenumber Selection in Recurrent Precipitation

We study invasion fronts in a class of simple, two-species reaction-diffusion systems that occur as models for recurrent precipitation and undercooled liquids. We exhibit several different modes of front propagation: the invasion of an unstable homogeneous equilibrium can create persistent periodic patterns, transient patterns, or simply a homogeneous state. We give criteria that distinguish be...

Wavenumber selection via spatial parameter jump.

The Swift-Hohenberg equation describes an instability which forms finite-wavenumber patterns near onset. We study this equation posed with a spatial inhomogeneity; a jump-type parameter that renders the zero solution stable for x<0 and unstable for x>0. Using normal forms and spatial dynamics, we prove the existence of a family of steady-state solutions that represent a transition in space from...

Measurement of the Spatial Evolution of the Deprotection Reaction Front with Nanometer Resolution using Neutron Reflectometry

The use of chemically amplified photoresists for the fabrication of sub-100 nm features will require spatial control with nanometer level resolution. To reach this goal, a detailed understanding of the complex reaction-diffusion mechanisms at these length scales is needed and will require high spatial resolution measurements. In particular, few experimental methods can directly measure the spat...

HIGH RESOLUTION LASER SPECTROSCOPY IN COLD SUPERSONIC MOLECULAR BEAMS COOLING, REDUCTION OF DOPPLER WIDTH AND APPLICATION

The cooling of molecules during the adiabatic expansion of supersonic seeded molecular beams is reviewed and illustrated by the example of NO -molecules. The reduction of the Doppler width by collimation of the beam and the cooling to low rotational temperatures brings a significant simplification of the complex NO -absorption spectrum and allows its assignment. The measured rotational tem...