Publications by authors named "Clayton S-C Yang"

Vibration-rotation signatures of intact water and complex organic molecules in vapor phase were detected, identified, and mode-assigned in the long-wave infrared emissions of laser-induced plasma. Time resolved long-wave infrared emissions were also studied to assess the temporal behaviors of these gaseous molecular emitters. The temperatures of these molecular vapors in the hot and transient vapor-plasma plume of the laser-induced plasma were estimated to be well above room temperatures during their existence.

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Long-wave infrared (LWIR) emissions of laser-induced plasma on solid potassium chloride and acetaminophen tablet surfaces were studied using both a one-dimensional (1-D) linear array detection system and, for the first time, a two-dimensional (2-D) focal plane array (FPA) detection system. Both atomic and molecular infrared emitters in the vicinity of the plasma were identified by analyzing the detected spectral signatures in the infrared region. Time- and space-resolved long-wave infrared emissions were also studied to assess the temporal and spatial behaviors of atomic and molecular emitters in the plasma.

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Laser Induced Breakdown Spectroscopy (LIBS) in the Ultra Violet/Visible/Near-IR (UVN) spectral range is a powerful analytical tool that facilitates the interpretation of Raman spectroscopic data by providing additional details in elemental chemistry. To acquire the complete information of molecular vibrations for more accurate and precise chemical bonding and structural analysis, an ideal optical sensing facility should be able to rapidly probe the broad vibrational dipole and polarizability responses of molecules by acquiring both Raman scattering and mid-IR emission spectroscopic signatures. Recently, the research team at Brimrose has developed a novel optical technology, Long-Wave IR (LWIR) LIBS.

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Raman spectroscopy and laser induced breakdown spectroscopy (LIBS) are complementary techniques that together can provide a comprehensive characterization of geologic environments. For landed missions with constrained access to target materials on other planetary bodies, discerning signatures of life and habitability can be daunting, particularly where the preservation of organic compounds that contain the building blocks of life is limited. The main challenge facing any spectroscopy measurements of natural samples is the complicated spectra that often contain signatures for multiple components, particularly in rocks that are composed of several minerals with surfaces colonized by microbes.

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The standoff detection range of the simultaneous ultraviolet/visible/near-infrared (UVN) + longwave-Infrared (LWIR) Laser Induced Breakdown Spectroscopy (LIBS) detection system has been successfully extended from merely 10 cm to ≥ 1 meter by adopting a reflecting telescope collection scheme and UVN + LWIR LIBS emission signatures were acquired in various atmospheres from soil and mineral samples. This system simultaneously captured emission signatures from atomic, and simple and complex molecular target species existing in or near the same laser-induce plasma plume within micro-seconds. These pioneer standoff measurements of UVN + LWIR LIBS signatures have revealed an abundance of plasma-generated sample molecular emitting species in their vapor state along with atomic ones which gave intense and distinct signature emissions in both UVN (conventional LIBS) and LWIR (LWIR LIBS) spectral regions.

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This is the first report of a simultaneous ultraviolet/visible/NIR and longwave infrared laser-induced breakdown spectroscopy (UVN + LWIR LIBS) measurement. In our attempt to study the feasibility of combining the newly developed rapid LWIR LIBS linear array detection system to existing rapid analytical techniques for a wide range of chemical analysis applications, two different solid pharmaceutical tablets, Tylenol arthritis pain and Bufferin, were studied using both a recently designed simultaneous UVN + LWIR LIBS detection system and a fast AOTF NIR (1200 to 2200 nm) spectrometer. Every simultaneous UVN + LWIR LIBS emission spectrum in this work was initiated by one single laser pulse-induced micro-plasma in the ambient air atmosphere.

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In this work, comparative long-wave infrared (LWIR) laser-induced breakdown spectroscopy (LIBS) emission studies of two excitation sources: conventional 1.064 μm and eye-safe laser wavelength at 1.574 μm were performed to analyze several widely-used inorganic energetic materials such as ammonium and potassium compounds as well as the organic liquid chemical warfare agent simulant, dimethyl methylphosphate (DMMP).

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Thin solid films made of high nitro (NO)/nitrate (NO) content explosives were deposited on sand-blasted aluminum substrates and then studied using a mercury-cadmium-telluride (MCT) linear array detection system that is capable of rapidly capturing a broad spectrum of atomic and molecular laser-induced breakdown spectroscopy (LIBS) emissions in the long-wave infrared region (LWIR; ∼5.6-10 µm). Despite the similarities of their chemical compositions and structures, thin films of three commonly used explosives (RDX, HMX, and PETN) studied in this work can be rapidly identified in the ambient air by their molecular LIBS emission signatures in the LWIR region.

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A mercury-cadmium-telluride linear array detection system that is capable of rapidly capturing (∼1-5 s) a broad spectrum of atomic and molecular laser-induced breakdown spectroscopy (LIBS) emissions in the long-wave infrared region (LWIR, ∼5.6-10 μm) was recently developed. Similar to the conventional ultraviolet-visible LIBS, a broadband emission spectrum of condensed phase samples covering a 5.

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Mid infrared time-resolved emission spectra were recorded from laser-induced carbon plasma. These spectra constitute the first study of carbon materials LIB spectroscopy in the mid infrared range. The carbon plasma was induced using a Q-switched Nd: YAG laser.

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In this work, we develop a mercury-cadmium-telluride linear array detection system that is capable of rapidly capturing (∼1-5  s) a broad spectrum of atomic and molecular laser-induced breakdown spectroscopy (LIBS) emissions in the long-wave infrared (LWIR) region (∼5.6-10  μm). Similar to the conventional UV-Vis LIBS, a broadband emission spectrum of condensed phase samples covering the whole 5.

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In an effort to augment the atomic emission spectra of conventional laser-induced breakdown spectroscopy (LIBS) and to provide an increase in selectivity, mid-wave to long-wave infrared (IR), LIBS studies were performed on several organic pharmaceuticals. Laser-induced breakdown spectroscopy signature molecular emissions of target organic compounds are observed for the first time in the IR fingerprint spectral region between 4-12 μm. The IR emission spectra of select organic pharmaceuticals closely correlate with their respective standard Fourier transform infrared spectra.

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Laser-induced breakdown spectroscopy (LIBS) has shown great promise for applications in chemical, biological, and explosives sensing and has significant potential for real-time standoff detection and analysis. In this study, LIBS emissions were obtained in the mid-infrared (MIR) and long-wave infrared (LWIR) spectral regions for potential applications in explosive material sensing. The IR spectroscopy region revealed vibrational and rotational signatures of functional groups in molecules and fragments thereof.

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Laser-induced breakdown spectroscopy (LIBS) is a powerful analytical technique for detecting and identifying trace elemental contaminants by monitoring the visible atomic emission from small plasmas. However, mid-infrared (MIR), generally referring to the wavelength range between 2.5 to 25 microm, molecular vibrational and rotational emissions generated by a sample during a LIBS event has not been reported.

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