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Search Publications by: Joseph T. Hodges (Fed)

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Displaying 26 - 50 of 106

Precise methane absorption measurements in the 1.64 micron spectral region for the MERLIN mission

June 2, 2016
Author(s)
Joseph T. Hodges, Stephen E. Maxwell, Zachary D. Reed, Hong Lin, Keeyon Sung, Malathy Devi, Thomas Warneke, Peter Spietz, Ha Tran, Thibault Delahaye
In this article we describe a high-precision laboratory targeting the R(6) manifold of the 2ν3 band of 12CH4. Accurate physical models of this absorption spectrum will be required by the Franco-German, Methane Remote Sensing LIDAR (MERLIN) space mission

Coherent cavity-enhanced dual-comb spectroscopy

May 4, 2016
Author(s)
Adam J. Fleisher, David A. Long, Zachary D. Reed, David F. Plusquellic, Joseph T. Hodges
Multiheterodyne spectroscopy performed with two stabilized optical frequency combs (OFCs) has shown great potential as a fast, accurate, and high-resolution substitute for existing interferometry methods that require lengthy integration times and precision

In-Situ Metrology to Characterize Water Vapor Delivery during Atomic Layer Deposition

May 2, 2016
Author(s)
Tariq Ahmido, William A. Kimes, Brent A. Sperling, Joseph T. Hodges, James E. Maslar
Water is often employed as the oxygen source in metal oxide atomic layer deposition (ALD) processes. It has been reported that variations in the amount of water delivered during metal oxide ALD can impact the oxide film properties. Hence, one contribution

Mid-infrared molecular spectroscopy in the quantum noise limit

March 31, 2016
Author(s)
David A. Long, Adam J. Fleisher, Qingnan Liu, Joseph T. Hodges
A cavity ring-down spectrometer was used to reach the quantum noise limit in the mid-infrared spectral region. Quantum noise was observed not only in the individual ring-down decay events but also in the corresponding ensemble statistics with a magnitude

Multispectrum analysis of the Oxygen A-band

March 25, 2016
Author(s)
Joseph T. Hodges, Brian J. Drouin, D C. Benner, L.R. Brown, Matthew J. Cich, Timothy Crawford, Malathy Devi, Alexandre Guillaume, Eli Mlawer, D J. Robichaud, Oyafuso Fabiano, Keeyon Sung, Wishnow Edward, Shanshan Yu
Retrievals of atmospheric composition from near-infrared measurements require measurements of airmass to better than the desired precision of the composition. The oxygen bands are obvious choices to quantify airmass since the mixing ratio of oxygen is

High accuracy CO2 line intensities determined from theory and experiment

June 15, 2015
Author(s)
Joseph T. Hodges, Oleg L. Polyansky, Katarzyna E. Bielska, Melanie C. Ghysels, Lorenzo Lodi, N Zobov, Jonathan Tennyson
The atmospheric concentration of carbon dioxide (CO2), with its consequences for the greenhouse effect and climate change, is being closely monitored by a variety of space-borne and ground-based remote sensing experiments. These experiments require a

Application of the Hartmann-Tran profile to analysis of H2O spectra

June 9, 2015
Author(s)
D Lisak, A. Cygan, D Bermejo, J L. Domenech, Joseph T. Hodges, Ha Tran
The Hartmann-Tran profile (HTP), which has been recently recommended as a new standard in spectroscopic databases, is used to analyze spectra of several lines of H$_2$O diluted in N$_2$, SF$_6$, and in pure H$_2$O. This profile accounts for various

One-dimensional frequency-based spectroscopy

May 22, 2015
Author(s)
Joseph T. Hodges, A. Cygan, P. Wcislo, S. Wojtewicz, Piotr Maslowski, R. Ciurylo, D Lisak
Recent developments in optical metrology have tremendously improved the precision and accuracy of the horizontal (frequency) axis in measured spectra. However, the vertical (typically absorbance) axis is usually based on intensity measurements that are

Cavity ring-down spectrometer for high-fidelity molecular absorption measurements

April 1, 2015
Author(s)
Vincent T. Sironneau, Hong Lin, Zachary Reed, Joseph T. Hodges
We present a cavity ring-down spectrometer which was developed for near-infrared measurements of laser absorption by atmospheric greenhouse gases. This system has several important attributes that make it possible to conduct broad spectral surveys and to

Line shapes, positions and intensities of water transitions near 1.28 microns

November 7, 2014
Author(s)
Vincent T. Sironneau, Joseph T. Hodges
We present measurements of approximately 70 isolated, self-broadened, water vapor lines which are assigned to the (1,0,1)(0,0,0), (0,0,2)(0,0,0), (1,2,0)(0,0,0), and (2,0,0)(0,0,0) vibrational bands and which occur in the transparency window region

Recommended isolated-line profile for representing high-resolution spectroscopic transitions

September 11, 2014
Author(s)
Joseph T. Hodges, Jonathan Tennyson, P F. Bernath, Alain Campargue, A Csaszar, L Daumont, R R. Gamache, D Lisak, Olga Naumenko, Lawrence Rothman, Ha Tran, N Zobov, Boone Chris, L Gianfrani, Jean M. Hartmann
Recommendations of an IUPAC Task Group formed in 2011 on “Intensities and line shapes in high-resolution spectra of water isotopologues from Experiment and Theory" (Project No. 2011-022-2- 100) on line profiles of high-resolution rotational-vibrational

Multiheterodyne spectroscopy with optical frequency combs generated from a continuous-wave laser

May 1, 2014
Author(s)
David A. Long, Adam J. Fleisher, Kevin O. Douglass, Stephen E. Maxwell, Katarzyna E. Bielska, Joseph T. Hodges, David F. Plusquellic
Dual-drive Mach-Zehnder modulators were utilized to produce power-leveled optical frequency combs (OFCs) from a continuous-wave laser. The resulting OFCs contained up to fifty unique frequency components and spanned more than 200 GHz. Simple changes to the

Isolated line shapes of molecular oxygen: ab initio calculations versus measurements

April 8, 2014
Author(s)
Vincent T. Sironneau, Joseph T. Hodges, Jean M. Hartmann, Julien Lamouroux
We present comparisons between measured isolated line shapes of molecular oxygen in air and those calculated, free of any adjusted parameter, using requantized Classical Molecular Dynamics Simulations (rCMDS). This work extends a previous study made for a

Quantum-noise-limited cavity ring-down spectroscopy

March 29, 2014
Author(s)
David A. Long, Adam J. Fleisher, Szymon S. Wojtewicz, Joseph T. Hodges
Spectroscopic techniques with ultra-high sensitivity allow for the study of a wide variety of physical and chemical phenomena, ranging from the interrogation of individual atoms1 and molecules2,3 to the quantitative extraction of ensemble properties from

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

High-Accuracy Measurements of the Vapor Pressure of Ice Referenced to the Triple Point

December 6, 2013
Author(s)
Katarzyna E. Bielska, Daniel K. Havey, Gregory E. Scace, D Lisak, Allan H. Harvey, Joseph T. Hodges
The vapor pressure of hexagonal (Ih) ice was measured over the temperature range 175 K to 253.4 K and referenced to the value at the triple point of water. This experiment combined a highly accurate humidity generation system containing an ice-coated

Spectral line shapes investigation with Pound-Drever-Hall-locked frequency-stabilized cavity ring-down spectroscopy

October 23, 2013
Author(s)
A. Cygan, S. Wojtewicz, J. Domyslawska, Piotr Maslowski, Katarzyna E. Bielska, M. Piwinski, K. Stec, R.S. Trawinski, F Ozimek, C. Radzewicz, Hisashi Abe, T. Ido, Joseph T. Hodges, D Lisak, R. Ciurylo
A review of recent experiments involving a newly developed Pound-Drever-Hall-locked frequency-stabilized cavity ring-down spectroscopy (PDH-locked FS-CRDS) system is presented. By comparison to standard FS-CRDS, the PDH lock of the probe laser to the ring

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

Direct measurements of mass-specific optical cross sections of single component aerosol mixtures

July 22, 2013
Author(s)
James Radney, Xiaofei Ma, Keith A. Gillis, Michael R. Zachariah, Joseph T. Hodges, Christopher D. Zangmeister
The optical properties of atmospheric aerosols vary widely, being dependent upon particle composition, morphology and mixing state. This diversity and complexity of aerosols motivates measurement techniques that can discriminate and quantify a variety of