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Displaying 126 - 150 of 188

Dependence of Soot Optical Properties on Particle Morphology: Measurements and Model Comparisons

February 18, 2014
Author(s)
James Radney, Rian You, Xiaofei Ma, Joseph Conny, Michael R. Zachariah, Joseph T. Hodges, Christopher D. Zangmeister
We measure the mass-specific absorption and extinction cross sections for laboratory-generated soot aerosols. Two soot morphologies are investigated, both comprising fractal aggregates of nearly spherical monomers. The first type consists of monomer chains

Filter Material Effects on Particle Absorption Characteristics

February 10, 2014
Author(s)
Cary Presser, Joseph M. Conny, Ashot Nazarian
The absorption coefficient and mass specific absorption cross section were determined for nigrosin-laden quartz, Teflon, and polycarbonate filters in inert surroundings at different steady-state temperatures and particle mass loadings. The objective was to

Chapter 3 Evaluation of Atmospheric Loss Processes

December 31, 2013
Author(s)
Vladimir L. Orkin, James B. Burkholder, Wahid Mellouki, Eric L. Fleming, Christian George, Charles H. Jackman, Timothy J. Wallington , Michael J. Kurylo , Dwayne E. Heard, William H. Swartz
Hydroxyl radical (OH), electronically excited atomic oxygen (O(1D)), and atomic chlorine (Cl) reaction rate coefficient data were evaluated and the estimated uncertainties in the recommended parameters reduced, in general, from those currently recommended

Achieving Climate Change Absolute Accuracy in Orbit

October 28, 2013
Author(s)
Bruce Wielicki, Joseph P. Rice
The Climate Absolute Radiance and Refractivity Observatory (CLARREO) mission will provide a metrology laboratory in orbit for the purpose of accurately measuring and attributing climate change. CLARREO measurements establish new climate change benchmarks

Rapid scan absorption spectroscopy using a waveform-driven electro-optic phase modulator in the 1.6- 1.65 ym region

September 25, 2013
Author(s)
Kevin O. Douglass, Stephen Maxwell, Gar W. Truong, Roger D. van Zee, Joseph T. Hodges, David Long, David F. Plusquellic
A method is reported for performing fast optical frequency scans over a bandwidth of 36.9 GHz and at a sweep rate of 40 kHz using a single second-order sideband from an electro-optic phase modulator driven by an arbitrary waveform generator. Single

A novel apparatus to measure reflected sunlight from the Moon

September 19, 2013
Author(s)
Claire E. Cramer, Gerald T. Fraser, Keith R. Lykke, John T. Woodward IV, Alan W. Smith
We describe a new apparatus for measuring the spectral irradiance of the Moon at visible wavelengths. Our effort builds upon the United States Geological Survey’s highly successful Robotic Lunar Observatory (ROLO), which determined a precise model for the

Open-Path Dual-Comb Spectroscopy of Greenhouse Gases

June 9, 2013
Author(s)
Greg B. Rieker, Fabrizio R. Giorgetta, William C. Swann, Ian R. Coddington, Laura C. Sinclair, Christopher L. Cromer, Esther Baumann, Alexander M. Zolot, Nathan R. Newbury
Frequency-comb spectroscopy in the near-infrared is used to measure atmospheric CO2 and H2O concentrations over a 2-km outdoor open-air path. This technique shows promise for measurements over length scales between point sensors and satellite systems.

Results from the International Halocarbons in Air Comparison Experiment (IHALACE)

June 1, 2013
Author(s)
Bradley Hall, George C. Rhoderick, A Engel, J. Muhle, J. W. Elkins, F. Artuso, E. Atlas, M. Aydin, D. Blake, E. G. Brunke, S. Chiavarini, P. J. Fraser, J. Happell, Paul B. Krummel, I. Levin, M. Loewenstein, M. Malone, S. A. Montzka, S. O'Doherty, S. Reimann, E. S. Saltzman, H. E. Scheel, L. P. Steele, M. K. Vollmer, R. F. Weiss, D. Worthy, Y. Yokouchi
The International Halocarbons in Air Comparison Experiment (IHALACE) was conducted to document relationships between calibrations scales among various laboratories that measure atmospheric greenhouse and ozone depleting gases. Six stainless steel cylinders

Photochemical Properties of Some Cl-Containing Halogenated Alkanes

May 31, 2013
Author(s)
Vladimir L. Orkin, Victor Khamaganov, E. E. Kasimovskaya, A G. Guschin
Rate constants for the gas phase reactions of OH radicals with three partially halogenated alkanes, CHCl3 (kMC), CHFClCFCl2 (k122a), and CH2CFCl2 (k132c), were measured using a discharge flow – electron paramagnetic resonance technique over the temperature

Differential cavity ring-down spectroscopy

May 9, 2013
Author(s)
Jeremie B. Courtois, Katarzyna E. Bielska, Joseph T. Hodges
We present a technique called differential cavity ring-down spectroscopy (D-CRDS) for reducing etaloning effects in a ring-down spectrometer. The method relies on alternately measuring and then subtracting intra-cavity losses associated with pairwise TEM00

The distance dependences and spatial uniformities of spectral irradiance standard lamps

October 19, 2012
Author(s)
Howard W. Yoon, Gary D. Graham, Robert D. Saunders, Yuqin Zong, Eric L. Shirley
We describe the characterization of a group of NIST spectral irradiance lamps at longer distances and larger angles than are typically issued by NIST. The spectral irradiances from the FEL lamps were measured from 50 cm to 150 cm at 8 different distances

Identification of Isethionic Acid and Other Small Molecule Metabolites of Fragilariopsis cylindrus with Nuclear Magnetic Resonance

July 8, 2012
Author(s)
Dan Bearden, Arezue F. Boroujerdi, Peter A. Lee, Giacomo R. DiTullio, Michael G. Janech, Sarah B. Vied
Nuclear magnetic resonance (NMR)-spectroscopy has been used to obtain metabolic profiles of the polar diatom Fragilariopsis cylindrus, leading to the identification of a novel metabolite in this organism. Initial results from an ongoing metabolomics study

The winter time South Pole tropospheric water vapor column: Comparisons of radiosonde and recent terahertz radiometry, use of the saturated column as a proxy measurement; and inference of decadal trends

July 7, 2012
Author(s)
Richard A. Chamberlin, Erich N. Grossman
We use a fifty year record of winter time radiosonde observations at the South Pole to estimate the precipitable water vapor column (PWV) over the entire period. Humidity data from older radiosondes is of limited reliability; however, we think an

SORCE SSI Workshop Summary

July 1, 2012
Author(s)
Joseph P. Rice, Jerald Harder, Martin Snow, Thomas Woods
Over 30 scientists and calibration specialists gathered at the National Institute of Standards and Technology (NIST) in Gaithersburg, Maryland, for the first Solar Spectral Irradiance (SSI) Variations Workshop, Feb. 28-March 1, 2012. The purpose of the

Direct-comb molecular spectroscopy with accurate, resolved comb teeth over 43 THz

February 15, 2012
Author(s)
Alexander M. Zolot, Fabrizio R. Giorgetta, Esther Baumann, Jeffrey W. Nicholson, William C. Swann, Ian R. Coddington, Nathan R. Newbury
We demonstrate a dual comb spectrometer using stabilized frequency combs spanning 176 THz to 219 THz (1370 nm to 1700 nm) in the near infrared. Measurements of amplitude and phase response at each individual comb tooth span the full 43 THz, generating ~430

High-resolution, high-accuracy dual comb spectroscopy with over 40 THz bandwidth

January 20, 2012
Author(s)
Alexander M. Zolot, Fabrizio R. Giorgetta, Esther Baumann, William C. Swann, Jeff Nicholson, Ian R. Coddington, Nathan R. Newbury
Most spectroscopic instruments directly measure optical wavelength, which is converted to frequency and calibrated against spectral features that have traditionally been measured using complicated frequency chain methods. In the past decade optical

2-Bromo-3,3,3-Trifluoropropene: OH Reaction Rate Constant, IR Absorption Spectrum, Ozone Depletion Potentials and Global Warming Potentials

December 30, 2011
Author(s)
Kenneth O. Patten, Victor Khamaganov, Vladimir L. Orkin, Steven L. Baughcum, Donald J. Wuebbles
The rate constant for the gas phase reaction of OH radicals with BTP (2-Bromo-3,3,3-trifluoropropene, CH2=CBrCF3) was measured using a flash photolysis resonance-fluorescence technique over the temperature range 220 K to 370 K. The Arrhenius plot was found
Displaying 126 - 150 of 188