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

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 B13 cluster with molecular oxygen, O2, 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 B13(+/0/-) cluster. The effect of sequential ionization on the formation of products is pronounced. In ionic B13 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. © 2010 American Institute of Physics

Initiating an Effective Personnel Development Program

This study identified the educational interests of library personnel and investigated whether level of interest was a valid indicator of program participation. In the fall semester of 1993, Eastern Illinois University’s Booth Library surveyed all administrators, faculty, and staff. The objectives of the survey were to identify: (1) indicators of educational interests of library personnel at a medium-sized university; (2) departmental differences in educational interests; and (3) the relationship between employee interest in educational programs and employee participation in programs developed

The terahertz infrared spectrum of cyclotrimethylenetrinitramine: Targeting anharmonic modes for the fingerprinting and detection of RDX

Recent approaches to the modeling of molecular solids have provided for a dramatic improvement in the prediction of zero Kelvin behavior for some properties of interest. Most notably the vibrational spectrum for these systems can now be calculated robustly via ab initio methods employing density functional theory. This improvement, however, leads to a quandary: the accurate physical modeling of these systems at zero Kelvin in many cases will not provide values and even physical behavior matching experimental values under ambient conditions. We examine this quandary in detail by considering zero Kelvin calculations using the B3LYP-D* functional of the terahertz infrared spectrum of the energetic material cyclotrimethylenetrinitramine (RDX). Most importantly we show what knowing the deviation from the simple harmonic approximation of a given mode at zero Kelvin says about the anharmonicity of the mode near ambient volumes. Finally, we discuss the practical implications for using ab initio calculations to create finger-prints for the detection of explosives such as RDX. © 2012 American Institute of Physics

Reactivity of neutral and charged B13 clusters with O \u3c sup\u3e 2 \u3c/sup\u3e : A theoretical study

The chemical reactivity of neutral, cationic, and anionic species of the gas phase B13 cluster with molecular oxygen, O2, 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 B13(+/0/-) cluster. The effect of sequential ionization on the formation of products is pronounced. In ionic B13 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. © 2010 American Institute of Physics

A review of hyperspectral imagers and comparison with respect to real time processing on space and aircraft platforms

© 1998 SPIE. All rights reserved. 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 (grating or prism), or Fourier transform. Each category has unique characteristics that lead 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 (HSIs). This paper provides an overview of the three basic categories of HSIs and then contrasts each with respect to current and planned processing capabilities

Interaction of nucleobases with silicon nanowires: A first-principles study

The interaction between the nucleic acid bases - adenine (A), guanine (G), cytosine (C), thymine (T) and uracil (U) - and a hydrogen-passivated silicon nanowire (SiNW) is investigated within the framework of density functional theory. The calculated binding energy of the nucleic acid bases with the SiNW shows the order: G \u3e A≈C≈T≈U. This suggests that the interaction strength of a hydrogen passivated SiNW with the nucleic acid bases is nearly the same-G being an exception. The electronic structure of the nucleobase-SiNW complex is used to further characterize the nature of the interaction showing that it is likely electrostatic in nature. © 2012 Elsevier B.V. All rights reserved

THRIFTI: Tomographic hyperspectral remote imaging fourier transform interferometer

Hyperspectral imaging spectrometers (HSIs) utilizing a 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

Elastic properties of Mg \u3c inf\u3e x Ti \u3c inf\u3e 1-x B \u3c inf\u3e 2 (07FTYJO first-principles calculations

The elastic properties, including elastic constants, bulk, and shear moduli, and anisotropic index of hexagonal MgxTi1-xB 2 (0 ≤ x ≤ 1) are obtained using a first-principles density-functional-theory method. A difference in chemical bonding occurs between Ti-rich and Mg-rich diborides, leading to significantly different elastic properties: a small elastic anisotropy with relatively large bulk and shear moduli for Ti-rich diborides with x \u3c 0.25, and a large elastic anisotropy and relatively small bulk and shear moduli for Mg-rich diborides with x \u3e 0.25. The calculated results reveal a dominant role of the interplanar metal-metal bonds in predicting the extent of shear elastic anisotropy in MgxTi1-xB2 (0 ≤ x ≤ 1). © 2011 American Physical Society