William J. Slough

Degradation of phosphorene in air: understanding at atomic level

Phosphorene is a promising two dimensional (2D) material with a direct band gap, high carrier mobility, and anisotropic electronic properties. Phosphorene-based electronic devices, however, are found to degrade upon exposure to air. In this paper, we provide an atomic level understanding of stability of phosphorene in terms of its interaction with O2 and H2O. The results based on density functional theory together with first principles molecular dynamics calculations show that O2 could spontaneously dissociate on phosphorene at room temperature. H2O will not strongly interact with pristine phosphorene, however, an exothermic reaction could occur if phosphorene is first oxidized. The pathway of oxidation first followed by exothermic reaction with water is the most likely route for the chemical degradation of the phosphorene-based devices in air.

THRIFTI: tomographic hyperspectral remote imaging Fourier transform interferometer

Hyperspectral imaging spectrometers (HSIs) utilizing Sagnac interferometer are throughput-limited if a slit is employed in their designs. This paper describes the Tomographic Hyperspectral Remote Imaging Fourier Transform Interferometer (THRIFTI) optical design. THRIFTI is capable of producing spectral autocorrelation fringe modulation over an image plane defined by a two-dimensional CCD array without the throughput disadvantage encountered by the Sagnac-based imaging spectrometers that incorporate a slit. This approach is utilized to recapture the full spatial-spectral characteristics of an image hypercube via tomography or linear deconvolution. In addition to its large throughput, THRIFTI is robust and simple to construct. The optical design of THRIFTI is discussed and the first experimental results are presented.

Reactivity of neutral and charged B13 clusters with O2: A theoretical study

The chemical reactivity of neutral, cationic, and anionic species of the gas phase B(13) cluster with molecular oxygen, O(2), was investigated using density functional theory. All three species of B(13) interact with an oxygen molecule to generate a variety of stable isomers, with those representing a dissociative chemisorption process forming the most stable configurations. Our results also show site-specific bonding of oxygen to the B(13)((+/0/-)) cluster. The effect of sequential ionization on the formation of products is pronounced. In ionic B(13) clusters, in addition to energetics, the spin of the reactants and products plays a vital role in determining the most favorable product channel. In addition, this study reveals a richness of phenomena requiring a unified consideration of energy, geometry, spin conversion, and details of the electronic structure not previously illustrated for the reactivity of boron clusters.

MTU-Kestrel airborne hyperspectral imaging campaigns of the Lake Superior ecosystem

The clear waters of Lake Superior constitute the heart of one of the most significant fresh water ecosystems in the world. Lake Superior is the worlds largest lake by surface area (82,100 km2) holding approximately 10% of the earths freshwater (12,230 km3) that is not locked into glaciers or ice caps. Although Superior is arguably the most significant fresh water ecosystem on earth, questions relating to the lake and its watershed remain unanswered, including the effects of human habitation, exploitation, and economic potential of the region. There is a great diversity of scientific disciplines with a common interest in remote sensing of the Lake Superior ecosystem which have the need for data at all spatial, spectral, and temporal scales-from scales supplied by satellites, ships or aircraft at low spatial, spectral or temporal resolution, to a requirement for synoptic high resolution spatial (approximately 1 meter)/spectral (1 - 10 nm) data. During May and August of 1998, two week-long data collection campaigns were performed using the Kestrel airborne visible hyperspectral imager to acquire hyperspectral data of a broad taxonomy of ecologically significant targets, including forests, urban areas, lakeshore zones and rivers, mining industry tailing basins, and the Lake itself. We will describe the Kestrel airborne hyperspectral sensor, the collection and data reduction methodology, and flight imagery from both campaigns.

Review of hyperspectral imagers and comparison with respect to real-time processing on space and aircraft platforms

Over the last decade, various designs for hyperspectral instruments have been developed and may be categorized roughly by the way in which they acquire hyperspectral data: via filter, dispersion, or Fourier transform. Each category has unique characteristics that led to differing processing needs. Fueled by increasing demands for real time hyperspectral data from space and aircraft platforms, a new generation of data processing capabilities are being developed by an increasingly large community with the objective of accommodating the high data rate produced by these hyperspectral imagers. This paper provides an overview of the three basic categories of HSIs and then contrast each with respect to current and planned processing capabilities.

CALCULATION OF RDX MOLECULAR CRYSTAL GEOMETRY AND VIBRATIONAL FREQUENCIES UNDER HYDROSTATIC PRESSURE

First‐principles calculations of the effects of hydrostatic pressure on RDX are performed using the all‐electron CRYSTAL06 program. The lattice constants and optimized internal coordinates are simultaneously obtained at ambient pressure and hydrostatic pressure up to 2.9 GPa. The vibrational frequencies as a function of pressure are also calculated and compared with experimental results from the literature.