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Displaying 28551 - 28575 of 73929

Time and Frequency-Domain Spectroscopy with Dual Frequency Combs

May 28, 2009
Author(s)
Nathan R. Newbury, Ian R. Coddington, William C. Swann
High-resolution spectroscopic measurements of the amplitude and phase spectra from a gas sample can be acquired by use of dual frequency combs. Here we discuss the corresponding gas signature in the time domain.

Topological Insulators and Metals in Atomic Optical Lattices

May 28, 2009
Author(s)
Tudor Stanescu, Victor Galitski, Jay Vaishnav, Charles W. Clark, Sankar Das Sarma
We propose the realization of topological quantum states with cold atoms trapped in an optical lattice. We discuss an experimental setup that generates a two-dimensional hexagonal lattice in the presence of a light-induced periodic vector potential, which

Understanding Insecure IT: Practical Risk Assessment

May 27, 2009
Author(s)
Simon Liu, D. Richard Kuhn, Hart Rossman
IT systems have long been at risk from vulnerable software, malicious actions, or inadvertent user errors, in addition to run-of-the-mill natural and human-made disasters. As we discussed in the last issue ( Surviving Insecure IT: Effective Patch

Comparison of Clinical Methods with Isotope Dilution ICP-MS for the New Standard Reference Material 955c Lead In Caprine Blood

May 26, 2009
Author(s)
Karen E. Murphy, Thomas W. Vetter, Gregory C. Turk, Christopher D. Palmer, Miles E. Lewis, Ciaran M. Geraghty, Patrick J. Parsons, William F. Guthrie
The National Institute of Standards and Technology (NIST) has developed Standard Reference Material (SRM) 955c, a new caprine-based, four-level blood standard with certified blood lead levels (BLLs) ranging from 0.4 µg/dL (0.02 µmol/L) Pb to 45 µg/dL (2.17

Packaging and interconnect technologies for GaN nanowire-based light emitting diodes

May 26, 2009
Author(s)
Norman A. Sanford, Myongjai Lee, Jen-Hau Cheng, Dragos Seghete, Steven M. George, John B. Schlager, Kristine A. Bertness
GaN nanowires grown along c-axis on a silicon substrate using molecular beam epitaxy have been identified as one of the best materials for future light emitting diodes (LEDs). These defectfree nanowires-based LEDs may reach the highest possible efficiency

A deep-UV optical frequency comb at 205 nm

May 25, 2009
Author(s)
Scott A. Diddams, E Peters, P Fendel, S Reinhardt, T W. Hansch, T Udem
By frequency quadrupling a picosecond pulse train from a Ti:sapphire laser at 820 nm we generate a frequency comb at 205 nm with nearly bandwidth-limited pulses. The nonlinear frequency conversion is accomplished by two successive frequency doubling stages

Absolute Ranging Using Frequency Combs

May 25, 2009
Author(s)
William C. Swann, Ian R. Coddington, Nathan R. Newbury
We present a technique for measuring absolute range that uses two mismatched frequency combs to measure distance over 1.5 m range with 10 nm level statistical uncertainty.

Carbon Nanomaterials Standards Efforts at NIST

May 24, 2009
Author(s)
Jeffrey A. Fagan
Development of carbon nano-materials for applications has been hindered to date by a lack of standard protocols, i.e. documentary standards, and physical standards such as reference materials, which enable the common inter-comparison between laboratories

Optimization of Accurate SEM Imaging by Use of Artificial Images

May 22, 2009
Author(s)
Petr Cizmar, Andras Vladar, Michael T. Postek
Today the vast majority of the scanning electron microscopes (SEMs) are incapable of taking repeatable and accurate images at high magnifications. Geometric distortions are common, so are drift, vibration, and problems related to disturbing electro

Capillary Instability in Nanoimprinted Polymer Films

May 21, 2009
Author(s)
Kyle J. Alvine, Yifu Ding, Hyun Wook Ro, Brian C. Okerberg, Alamgir Karim, Christopher L. Soles, Jack F. Douglas
Capillary forces play an active role in defining the equilibrium structure of nanoscale structures. This effect can be especially pronounced in soft materials such as polymers near or above their glass transition temperatures where material flow is

Direct Imaging of Current Driven Domain Walls in Ferromagnetic Nanostripes

May 21, 2009
Author(s)
Willard C. Uhlig, Michael J. Donahue, Daniel T. Pierce, John Unguris
To better understand the response of domain walls to current induced spin transfer torques, we have directly imaged the internal magnetic structure of domain walls in current-carrying ferromagnetic nanostripes. Domain wall images were acquired both while a

A Design-of-Experiments Plug-In for Estimating Uncertainties in Finite Element Simulations

May 18, 2009
Author(s)
Jeffrey T. Fong, Roland deWit, Pedro V. Marcal, James J. Filliben, Nathanael A. Heckert
The objective of this paper is to introduce an economical and user-friendly technique for estimating a specific type of finite element simulation uncertainties, or, "error bars," for a class of mathematical models, of which no closed-form or approximate

Large Random Telegraph Noise in Sub-Threshold Operation of Nano-Scale nMOSFETs

May 18, 2009
Author(s)
Jason P. Campbell, Liangchun (. Yu, Kin P. Cheung, Jin Qin, John S. Suehle, A Oates, Kuang Sheng
We utilize low-frequency noise measurements to examine the sub-threshold voltage (sub-VTH) operation of highly scaled devices. We find that the sub-VTH low-frequency noise is dominated by random telegraph noise (RTN). The RTN is exacerbated both by channel

The Negative Bias Temperature Instability vs. High-Field Stress Paradigm

May 18, 2009
Author(s)
Jason P. Campbell, Kin P. Cheung, John S. Suehle, A Oates
A new and more accurate fast-IDVG measurement methodology is utilized to examine the transient degradation and recovery associated with the negative-bias temperature instability (NBTI). The results reveal that the anomalously large initial degradations

Observing the Quantization of Zero Mass Carriers in Graphene

May 15, 2009
Author(s)
Joseph A. Stroscio, Gregory M. Rutter, D. L. Miller, K. Kubista, W. A. de Heer, Phillip N. First
Application of a magnetic field to conductors causes the charge carriers to circulate in cyclotron orbits with quantized energies called Landau levels (LLs). These are equally spaced in normal metals and two-dimensional electron gases. In graphene, however
Displaying 28551 - 28575 of 73929
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