A5091493612- Spectroscopy and Laser Applications
- Advanced Fiber Laser Technologies
- Atmospheric Ozone and Climate
- Atmospheric and Environmental Gas Dynamics
- Photonic and Optical Devices
- Mass Spectrometry Techniques and Applications
- Spectroscopy and Quantum Chemical Studies
- Photochemistry and Electron Transfer Studies
- Molecular Spectroscopy and Structure
- Analytical Chemistry and Sensors
- Advanced Chemical Physics Studies
- Gas Sensing Nanomaterials and Sensors
- Semiconductor Lasers and Optical Devices
- Laser-Matter Interactions and Applications
- Quantum optics and atomic interactions
- Atomic and Subatomic Physics Research
- Chemical Thermodynamics and Molecular Structure
- Crystallization and Solubility Studies
- Laser Design and Applications
- X-ray Diffraction in Crystallography
- Solid State Laser Technologies
- Advanced Chemical Sensor Technologies
- Water Quality Monitoring and Analysis
- Molecular spectroscopy and chirality
- Spectroscopy Techniques in Biomedical and Chemical Research
National Institute of Standards and Technology
2015-2024
Material Measurement Laboratory
2015-2024
National Institute of Standards
2014-2024
Physical Measurement Laboratory
2017
University of Colorado Boulder
2014
University of Pittsburgh
2009-2012
Elizabethtown College
2005-2010
University of California, San Diego
2010
Banner Alzheimer’s Institute
2010
UC San Diego Health System
2009
The HITRAN database is a compilation of molecular spectroscopic parameters. It was established in the early 1970s and used by various computer codes to predict simulate transmission emission light gaseous media (with an emphasis on terrestrial planetary atmospheres). composed five major components: line-by-line parameters required for high-resolution radiative-transfer codes, experimental infrared absorption cross-sections (for molecules where it not yet feasible representation form),...
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 50 unique components and spanned more than 200 GHz. Simple changes the modulation allowed for agile control of comb spacing. These then broadband, multiheterodyne measurements CO2 using both multipass cell an cavity. This technique allows robust trace gas species alleviates much cost complexity associated with use femtosecond...
We demonstrate time-resolved frequency comb spectroscopy (TRFCS), a new broadband absorption technique for the study of trace free radicals on microsecond timescale. apply TRFCS to time-resolved, mid-infrared deuterated hydroxyformyl radical trans-DOCO, an important short-lived intermediate along OD + CO reaction path. Directly after photolysis chemical precursor acrylic acid-d1, we measure absolute trans-DOCO product concentrations with sensitivity 5 × 10(10) cm(-3) and observe its...
We present and characterize a 2-D imaging spectrometer based on virtually-imaged phased array (VIPA) disperser for rapid, high-resolution molecular detection using mid-infrared (MIR) frequency combs at 3.1 3.8 \mu m. demonstrate of CH4 m with >3750 resolution elements spanning >80 nm ~600 MHz in <10 s acquisition time. In addition to broadband detection, time-resolved single-image is demonstrated by capturing dynamic concentration changes rate ~375 frames per second. Changes absorption above...
High-precision measurements of radiocarbon (14C) near or below a fraction modern 14C 1 (F14C ≤ 1) are challenging and costly. An accurate, ultrasensitive linear absorption approach to detecting would provide simple robust benchtop alternative off-site accelerator mass spectrometry facilities. Here we report the quantitative measurement in gas-phase samples CO2 with F14C < using cavity ring-down spectroscopy regime. Repeated analysis derived from combustion either biogenic petrogenic sources...
An optical frequency comb generated with an electro-optic phase modulator and a chirped radio-frequency waveform is used to perform pump-probe spectroscopy on the ${D}_{1}$ ${D}_{2}$ transitions of atomic potassium at 770.1 766.7 nm, respectively. With tooth spacing 200 kHz bandwidth 2 GHz hyperfine can be observed simultaneously. Interferograms are recorded in as little 5 \textmu{}s (a timescale corresponding inverse spacing). Importantly, sub-Doppler features measured long laser carrier...
We present high-reflectivity substrate-transferred single-crystal GaAs/AlGaAs interference coatings at a center wavelength of 4.54 μm with record-low excess optical loss below 10 parts per million. These high-performance mirrors are realized via novel microfabrication process that differs significantly from the production amorphous multilayers generated physical vapor deposition processes. This new enables reduced scatter due to low surface and interfacial roughness, while background doping...
Dual-comb spectroscopy allows for the rapid, multiplexed acquisition of high-resolution spectra without need moving parts or low-resolution dispersive optics. This method broadband is most often accomplished via tight phase locking two mode-locked lasers sophisticated signal processing algorithms, and therefore, long integration times coherent signals are difficult to achieve. Here we demonstrate an alternative approach dual-comb using modulator combs originating from a single...
Cavity ring-down spectroscopy is a ubiquitous optical method used to study light-matter interactions with high resolution, sensitivity and accuracy. However, it has never been performed the multiplexing advantages of direct frequency comb without significantly compromising spectral resolution. We present dual-comb cavity (DC-CRDS) based on parallel heterodyne detection signals local oscillator yield absorption dispersion spectra. These spectra are obtained from widths positions modes. two...
Successful evaluation of atmospheric gas composition relies on complementary efforts from experimental campaigns, laboratory metrology, and quantum chemistry theory. When these three areas work in concert, we significantly improve our ability to accurately describe understand chemical behavior. Here will discuss techniques employed NIST&#8217;s Optical Measurements Group perform precise sample analysis provide reference-grade spectroscopic data that is critical for Earth exoplanet...
To accurately attribute sources and sinks of molecules like CO_{2}, remote sensing missions require line intensities (S) with relative uncertainties u_{r}(S)<0.1%. However, discrepancies in S ≈1% are common when comparing different experiments, thus limiting their potential impact. Here we report a cavity ring-down spectroscopy multi-instrument comparison which revealed that the hardware used to digitize analog signals caused variability spectral integrals yield S. Our refined approach...
We demonstrate the precision molecular spectroscopy of H13CN using a free-running, all-fiber dual electro-optic frequency comb system. Successive interferograms, acquired at rate Δfrep=1 MHz, were phase-corrected in post-processing, averaged, and normalized to yield complex transmission spectrum several transitions within 2ν1H13CN band centered near λ=1545 nm. With spectral signal-to-noise ratios as high 326:1 achieved 2 ms integration time, we report accurate measurements transition...
High-finesse optical resonators found in ultrasensitive laser spectrometers utilize supermirrors ideally consisting of isotropic high-reflectivity coatings. Strictly speaking, however, the coatings are often nonuniformly stressed during deposition process and therefore do possess some small amount birefringence. When physically mounted cavity mirrors can be additionally such a way that large birefringence is induced. Here we report direct measurement two-mirror Fabry-P\'erot with $R=99.99%$...
Abstract Two cavity ring‐down spectrometers were employed to accurately measure line intensities in a series of near‐infrared carbon dioxide bands including (30012) ← (00001), (30013) and (30014) (00001) near 1.6 μm. Relative combined standard uncertainties for these band less than 0.1% showed significant, percent‐level deviations with respect many existing spectroscopic databases (although close agreement was observed the HITRAN 2016 database bands). Further, resulting utilized Total Carbon...
Abstract For trace gas sensing and precision spectroscopy, optical cavities incorporating low-loss mirrors are indispensable for path length intensity enhancement. Optical interference coatings in the visible near-infrared (NIR) spectral regions have achieved total losses below 2 parts per million (ppm), enabling a cavity finesse excess of 1 million. However, such advancements been lacking mid-infrared (MIR), despite substantial scientific interest. Here, we demonstrate significant...
Abstract Plasma-activated chemical transformations promise the efficient synthesis of salient products. However, reaction pathways that lead to desirable products are often unknown, and key quantum-state-resolved information regarding involved molecular species is lacking. Here we use quantum cascade laser dual-comb spectroscopy (QCL-DCS) probe plasma-activated NH 3 generation with rotational vibrational state resolution, quantifying state-specific number densities via broadband spectral...
We describe an ultra-sensitive cavity ring-down spectrometer which operates in the mid-infrared spectral region near 4.5 μm. With this instrument a noise-equivalent absorption coefficient of 2.6×10
An approach for dual-comb spectroscopy using electro-optic (EO) phase modulation is reported. Maximum-length pseudo-random binary sequences allow energy-efficient and flexible comb generation. Self-correction of interferograms shown to remove relative drifts improve mutual coherence, even EO combs derived from the same laser source. Methane reported over a ∼10 GHz spectral range, limited by modulators' bandwidth. The potential simple instrument demonstrated rapidly quantify atmospheric...
We report Doppler-free two-photon absorption of N$_2$O at $\lambda$ = 4.53 $\mu$m, measured by cavity ring-down spectroscopy. High power was achieved optical self-locking a quantum cascade laser to linear resonator finesse $F$ 22730, and accurate detuning over 400 MHz range relative an frequency comb. At sample pressure p 0.13 kPa, we large cross-section $\sigma_{13}^{(2)}$ 8.0 $\times$ 10$^{-41}$ cm$^4$ s molecule$^{-1}$ for the $Q$(18) rovibrational transition resonant $\nu_0$ 66179400.8 MHz.