An official website of the United States government
Here’s how you know
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.
Nathan R. Newbury, Ian R. Coddington, William C. Swann
Coherent dual comb spectroscopy can provide high-resolution, high-accuracy measurements of a sample response in both magnitude and phase. We discuss the achievable signal-to-noise ratio (SNR) due to both additive white noise and multiplicative noise, and
Bhaskar Godugu, Pedatsur Neta, Yamil Simon, Stephen Stein
A prominent dissociation path for electrospray generated tryptic peptide ions is the dissociation of the peptide bond linking the second and third residues from the amino-terminus. The formation of the resulting b 2 and y n-2 fragments has been
William C. Davis, Rolf L. Zeisler, John R. Sieber, Lee L. Yu
Two independent liquid chromatography inductively coupled plasma mass spectrometry (LC/ICP-MS) methods for the separation of arsenic species in urine have been developed with quantification by standard additions. Seven arsenic species have been quantified
Interest in the domestic production of bio-derived fuels, sparked by the high cost of petroleum crude oil, the potential of supply disruptions, and fears about climate change has lead to consideration of fluids to replace or extend conventional petroleum
This tutorial discusses the importance of citing valid uncertainties when reporting analytical results and the need for a universally accepted approach for evaluating uncertainties. Today, the CIPM procedure has been accepted by numerous international
Collision-induced dissociation of the benzylammonium and the 4-tert butyl benzylammonium ions was studied experimentally in an electrospray ionization quadrupole-hexapole-quadrupole tandem mass spectrometer. Ion fragmentation efficiencies were determined
Aimed at improving quality assurance and quantitation for modern fluorescence techniques, ASTM is about to release a Standard Guide for Fluorescence, reviewed here. The guide s main focus is on steady state fluorometry, for which available standards and
A high quality x-ray spectrum image of a 3.3 μm diameter sphere of K411 glass resting on a copper substrate was collected at 25 keV. The same sample configuration was modeled using the NISTMonte Monte Carlo simulation of electron and x-ray transport as is
Sara E. Mason, Anne M. Chaka, Thomas P. Trainor, Christopher Iceman
The ability to apply existing density functional theory-based modeling techniques to timely research problems in environmental chemistry is demonstrated by an {\em ab initio} thermodynamics investigation of stable hydrated oxide surface models and a
John A. Howarter, Edwin Chan, Christopher Stafford
Microstructural and hierarchical patterns are able to enhance the fracture toughness of adhesive interfaces. This phenomenon has been observed naturally in the design of foot pads of insects and other small animals such as the gecko. By understanding the
Mark M. Bailey, Christine M. Mahoney, Elodie Dempah, Jeffrey M. Davis, Matthew Becker, Supang Khondee, Eric J. Munson, Cory J. Berkland
Nanomaterials have emerged as valuable tools in biomedical imaging techniques, such as magnetic resonance imaging (MRI), fluorescence, positron emission tomography (PET), and others. Some have been designed to serve as multimodal imaging agents, combining
Young Jong Lee, Sapun Parekh, Yeon Ho Kim, Marcus T. Cicerone
We demonstrate that an optimized 2-pulse broadband coherent anti-Stokes Raman scattering (CARS) technique can be used to simultaneously measure vibrational dephasing times over a broad frequency range of Raman modes (between 500 cm-1 and 3100 cm-1). This
A local excitation of ferromagnetic resonance (FMR) and its detection were performed by using an open-ended radio frequency (RF) probe. THe RF probe is composed of a coaxial cable transmitting broadband RF waves over 10 GHz and a sharp tip attached to its
Vitamin D exists in two major forms, vitamin D3 and vitamin D2. Vitamin D helps the body absorb calcium and promote optimal growth. Both forms of vitamin D are metabolized to 25-hydroxyvitamin D in the body, and the levels of 25-hydroxyvitamin D3 (25-(OH
A Raman microscope utilizing a total internal reflection (TIR), annular illumination geometry through a ZnSe solid immersion lens (SIL) is described. Spectra of a thin film sample of the transparent organic conductor poly(3,4-ethylenedioxythiophene) poly
Kurt D. Benkstein, Baranidharan Raman, Christopher B. Montgomery, C Martinez, Stephen Semancik
We evaluated MEMS microsensor array with chemi-resistive elements for use as a non-invasive clinical diagnostic tool to detect the presence or absence of trace amounts of disease biomarkers in simulated breath samples. The microsensor environment was
A gas saturation apparatus capable of simultaneous measurements on eighteen samples was used for this work. The vapor pressures of 2-nitrotoluene (2-NT), 3-nitrotoluene (3-NT), 4-nitrotoluene (4-NT) and n-tetradecane (a control compound) were measured with
Li-Hong Xu, Jon T. Hougen, Jonathan M. Fisher, Ronald M. Lees
The aim of the present paper is to investigate the use of quantum chemistry calculations to obtain the torsional dependence of various structural and vibrational-force-field-related quantities that could help in estimating the vibration-torsion-rotation
George C. Rhoderick, David L. Duewer, Li Ning, Kathryn DeSirant
Studies of climate change increasingly recognize the diverse influences exerted by hydrocarbons in the atmosphere, including roles in particulates and ozone formation. Measurements of key non-methane hydrocarbons (NMHCs) suggest atmospheric concentrations
Nathan R. Newbury, Ian R. Coddington, William C. Swann
We discuss highly coherent fiber-based frequency combs and some of their applications to precision measurements in optical metrology, ranging, and spectroscopy.
Lane C. Sander, Katrice A. Lippa, Catherine A. Rimmer, Maximilian Kuhnle, Volker Friebolin, Klaus Albert
The relationship between alkyl phase structure and chromatographic performance is investigated for a series of octadecyl (C18)- modified silica surfaces with defined spacing of the alkyl surface by a pre-endcapping technique. Stationary phases were
Mariona Coll Bau, Curt A. Richter, Christina Hacker
Nanoelectronic fabrication with Flip chip lamination Mariona Coll, CA Richter, CA Hacker, Colloquium Catalan Institute of Nanoscience and Nanotechnology CIN2, Barcelona Spain, Dec 2009.