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Chemistry

Analytical chemistry

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Displaying 1026 - 1050 of 2086

Time-Resolved Infrared Spectroscopy of an [FeFe]-Hydrogenase Model Compound

March 26, 2012
Author(s)
Edwin J. Heilweil
Naturally occurring hydrogenases catalyze the reaction of H+ to form H2 gas. To develop a hydrogen source that is not reliant on fossil fuels, synthetic [FeFe]-hydrogenase model species are being studied. These compounds have a wing-like structure with a

In Situ Raman Monitoring of Ring-Opening Copolymerizations

March 25, 2012
Author(s)
Matthew T. Hunley, Santanu S. Kundu, Peter M. Johnson, Kathryn Beers
Recent advances in enzyme, metal, and organic catalysts have enabled the development of advanced functional polymers from cyclic ester and cyclic carbonate monomers. In this work, we present an in situ technique to monitor ring-opening polymerization using

Environmental Metabolomics

March 15, 2012
Author(s)
Daniel W. Bearden
The application of metabolomics in the field of environmental science or ecology, which has developed based substantially on NMR spectroscopic approaches, is a fast paced, rapidly developing field which seems to be poised to help re-frame the discussion of

Rippling Instability of Supported Polymer Nanolines

February 21, 2012
Author(s)
Vijaya R. Tirumala, Christopher M. Stafford, Leonidas E. Ocola, Jack F. Douglas, L. Mahadevan
The swelling response of polymer line gratings supported on a rigid substrate has direct implications on their mechanical stability during pattern transfer in nanofabrication. The polymer lines, when swollen in a good solvent, undergo a rippling

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

Measurements and Modeling Study on a High-Aromatic Diesel Fuel

January 31, 2012
Author(s)
Bret Windom, Marcia L. Huber, Thomas J. Bruno, A L. Lown, C T. Lira
The increasing cost of diesel fuel, potential for supply disruptions, and environmental concerns have resulted in a great deal of research to improve the performance and efficiency of diesel engines. This includes significant efforts in the reformulation

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

First high-resolution analysis of the nu15, nu12, nu5, nu10 and nu2 bands of oxirane

January 15, 2012
Author(s)
Walter J. Lafferty, Jean-Marie Flaud, F. Kwabia Tchana, A. Perrin
Fourier transform spectra of Oxirane (ethylene oxide, c-C2H4O) have been recorded in the 730 cm-1 to 1560 cm-1 (6.4 to 13.7 µm) spectral region using a Bruker IFS125HR spectrometer at a resolution of 0.0019 cm-1. A total of six vibration bands, ν15, ν12

Pilot Estuarine Mesocosm Study on the Environmental Fate of Silver Nanomaterials Leached from Consumer Products

January 10, 2012
Author(s)
Danielle Cleveland, Stephen E. Long, Paul L. Pennington, Emily Cooper, Michael H. Fulton, Geoffrey I. Scott, Elijah J. Petersen, Timothy M. Brewer, Jeffrey M. Davis, Laura J. Wood
Although nanosilver consumer products (CPs) now enjoy widespread availability, little work has been done to determine the environmental fate and leaching of silver nanoparticles (AgNPs) from these products. This type of work is crucial, since the lifecycle

Predictive Gold Nanocluster Formation Controlled by Metal-Ligand Complexes

January 9, 2012
Author(s)
John M. Pettibone, Jeffrey W. Hudgens
The formation of ligand-protected transition metal nanoclusters in size-selective syntheses is driven by the inherent properties of the protecting ligands. We have previously reported the selective, monodisperse product formation of phosphine protected Au

Surface Plasmon Polariton Raman Microscopy

January 1, 2012
Author(s)
Hae-Wook Yoo, Lee J. Richter, Hee-Tae Jung, Chris A. Michaels
We report surface plasmon polariton (SPP) mediated Raman microscopy on dielectric films in contact with a Ag layer at 785 nm with spatial resolution approaching the optical diffraction limit and reasonable spectral acquisition times. The excitation and

The BIOREMA project part 3: International interlaboratory comparison for bio-ethanol test methods

January 1, 2012
Author(s)
Michele M. Schantz, Adriaan van der Veen, Hugo Ent, Annaratia Baldan, Valnei Cunha, Romeu Daroda, Manuela Ulberth-Buchgraber, Brian E. Lang, Andrea Held, Ruth Hearn, Richard Brown, Paul Brewer
The main objective of the BIOREMA (Reference Materials for Biofuel Specifications) project is the development of two test materials (one bio-ethanol material and one biodiesel material) with well-established reference values. This paper describes the

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

Spectroscopy of the methane N3 Band with an accurate midinfrared coherent dual-comb spectrometer

December 28, 2011
Author(s)
Esther Baumann, Fabrizio R. Giorgetta, William C. Swann, Alexander M. Zolot, Ian R. Coddington, Nathan R. Newbury
We demonstrate a high-accuracy dual-comb spectrometer centered at 3.4 υm. The amplitude and phase spectra of the P,, Q, and partial R branches of the methane Ņ3 band are measured at 25 to 100 MHz point spacing with resolution under 10 kHz and a signal-to
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