New 224 nm Hollow Cathode Laser-UV Raman Spectrometer

Sparrow, Mark C.; Jackovitz, John F.; Munro, C. H.; Hug, W.; Asher, Sanford A.

doi:10.1366/0003702011951263

Cited by 28 publications

(18 citation statements)

References 20 publications

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“…Both near infrared (NIR) and deep UV laser (224-266 nm) excited micro-Raman spectroscopic strategies have been proposed for the search for life on Mars, in particular the detection of bi-molecules [32][33][34][35] . The NIR excited Raman spectra have minimum fluorescence from bio-molecules and provide molecular fingerprints of bio-molecules as well as of the substrate.…”

Section: Astrobiological Considerationsmentioning

confidence: 99%

A remote Raman system for planetary exploration: evaluating remote Raman efficiency

et al. 2004

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Landers and rovers are important to solar system exploration, and we are designing and analyzing a remote Raman system for a planetary mission. Raman spectroscopy is a common and powerful technique for materials analysis. We have developed a system that enables Raman spectroscopic measurements at distances of more than 50 meters. In order to design a flight instrument, we need to quantitatively understand the Raman efficiency of natural surfaces. We define remote Raman efficiency as the ratio of radiant exitance leaving a natural surface to the irradiance of the incident laser. The radiant exitance of a natural surface is the product of the sample radiance (minus background), the projected solid angle in steradians, and the spectral bandwidth of the spectrometer. The laser irradiance is the product of the energy of the laser (mJ/pulse) and the pulse rate (Hz), divided by the area of the laser spot. We have determined the remote Raman efficiency for several minerals and rocks: dolomite marble, dacite, milky quartz, anorthosite, calcite, biotite granite, magnesite, chert, gypsum (selenite), fibrous gypsum, and sandstone. By quantifying the remote Raman efficiency, we will be able to determine the number and quality of spectra that a remote Raman system can acquire on a planetary surface where available power is limited. Studies on hematite indicate that Raman shift (and thus remote Raman efficiency) depends on laser wavelength.

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Section: Astrobiological Considerationsmentioning

confidence: 99%

A remote Raman system for planetary exploration: evaluating remote Raman efficiency

et al. 2004

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“…Asher [2] [3] showed that natural materials did not fluoresce below a wavelength about 270nm, independent of the excitation wavelength. This was further proven in many subsequent publications such as Nelson [4], Sparrow [5], Wu [6], and many others. When excitation occurs below about 250nm, a fluorescence-free region exists above the laser wavelength in which to observe Raman spectra.…”

Section: Introductionmentioning

confidence: 61%

Improved sensing using simultaneous deep-UV Raman and fluorescence detection-II

et al. 2014

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Photon Systems in collaboration with JPL is continuing development of a new technology robot-mounted or hand-held sensor for reagentless, short-range, standoff detection and identification of trace levels chemical, biological, and explosive (CBE) materials on surfaces. This deep ultraviolet CBE sensor is the result of Army STTR and DTRA programs. The evolving 10 to 15 lb, 20 W, sensor can discriminate CBE from background clutter materials using a fusion of deep UV excited resonance Raman (RR) and laser induced native fluorescence (LINF) emissions collected is less than 1 ms. RR is a method that provides information about molecular bonds, while LINF spectroscopy is a much more sensitive method that provides information regarding the electronic configuration of target molecules.Standoff excitation of suspicious packages, vehicles, persons, and other objects that may contain hazardous materials is accomplished using excitation in the deep UV where there are four main advantages compared to near-UV, visible or near-IR counterparts. 1) Excited between 220 and 250 nm, Raman emission occur within a fluorescence-free region of the spectrum, eliminating obscuration of weak Raman signals by fluorescence from target or surrounding materials. 2) Because Raman and fluorescence occupy separate spectral regions, detection can be done simultaneously, providing an orthogonal set of information to improve both sensitivity and lower false alarm rates. 3) Rayleigh law and resonance effects increase Raman signal strength and sensitivity of detection. 4) Penetration depth into target in the deep UV is short, providing spatial/spectral separation of a target material from its background or substrate. 5) Detection in the deep UV eliminates ambient light background and enable daylight detection.

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“…Asher has shown that the wavelength range of fluorescence emission from organic materials is generally longer than 260 nm. [22][23][24][25] This advantage was further proven subsequent publications by Nelson [26], Sparrow [27], Wu [28], and many others. The concept of using fluorescence to detect threat agents or organisms by monitoring fluorescent tags, [29,30] or degradation products [31,32], is well established in the literature.…”

Section: Fluorescence Applications To Surface Analysismentioning

confidence: 81%

Long-range standoff detection of chemical, biological, and explosive hazards on surfaces

Fountain

Guicheteau

Pearman³

et al. 2010

SPIE Proceedings

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Fielded surface detection systems rely on contact with either the liquid contamination itself or the associated chemical vapor above the contaminated surface and do not provide a standoff or remote detection capability. Conversely, standoff chemical vapor sensing techniques have not shown efficacy in detecting those contaminants as liquids or solids on surfaces. There are a number of optical or spectroscopic techniques that could be applied to this problem of standoff chemical detection on surfaces. The three techniques that have received the most interest and development are laser induced breakdown spectroscopy (LIBS), fluorescence, and Raman spectroscopy. Details will be presented on the development of these techniques and their applicability to detecting CBRNE contamination on surfaces.

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New 224 nm Hollow Cathode Laser-UV Raman Spectrometer

Cited by 28 publications

References 20 publications

A remote Raman system for planetary exploration: evaluating remote Raman efficiency

A remote Raman system for planetary exploration: evaluating remote Raman efficiency

Improved sensing using simultaneous deep-UV Raman and fluorescence detection-II

Long-range standoff detection of chemical, biological, and explosive hazards on surfaces

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