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Search Publications by: Joseph T. Hodges (Fed)

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Displaying 51 - 75 of 214

Multiplexed sub-Doppler spectroscopy with an optical frequency comb

December 13, 2016
Author(s)
David A. Long, Adam J. Fleisher, David F. Plusquellic, Joseph T. Hodges
An optical frequency comb generated with an electro-optic phase modulator and a chirped radiofrequency waveform is used to perform saturation spectroscopy on the D1 and D2 transitions of atomic potassium. With a comb tooth spacing of 2 MHz and a bandwidth

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

Frequency-agile, rapid scanning cavity ring-down spectroscopy (FARS-CRDS) measurements of the (30012) --(00001) near-infrared carbon dioxide band

April 3, 2015
Author(s)
David A. Long, Szymon S. Wojtewicz, Charles E. Miller, Joseph T. Hodges
We present new high accuracy measurements of the (30012)←(00001) CO¬2 band near 1575 nm recorded with a frequency-agile, rapid scanning cavity ring-down spectrometer. The resulting spectra were fit with the partially correlated, quadratic-speed-dependent

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