Effects of Pressure on the Optical Emissions Observed from Solids Immersed in Water Using a Single Pulse Laser

Thornton, Blair; Ura, Tamaki

doi:10.1143/apex.4.022702

Cited by 60 publications

(44 citation statements)

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“…Similar results have also been reported independently by our group (Masamura et al, 2011) and the Ocean University of China (Hou et al, 2014). In Thornton and Ura (2011), the authors further demonstrated that narrow spectra can be observed from water immersed solids using a single-pulse with no significant effect of pressure up to 30 MPa. The difference in behavior observed for the single and double-pulse methods at high hydrostatic pressures has been linked to the transient pressure shockwaves generated when a high power laser-pulse is focused in a nearly incompressible medium such as water (Thornton et al, 2012a(Thornton et al, , 2014a.…”

Section: Underwater Libs At High Pressuresupporting

confidence: 85%

Development of a deep-sea laser-induced breakdown spectrometer for in situ multi-element chemical analysis

Thornton

Takahashi

Sato

et al. 2015

Deep Sea Research Part I: Oceanographic Research Papers

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159

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a b s t r a c tSpectroscopy is emerging as a technique that can expand the envelope of modern oceanographic sensors. The selectivity of spectroscopic techniques enables a single instrument to measure multiple components of the marine environment and can form the basis for versatile tools to perform in situ geochemical analysis. We have developed a deep-sea laser-induced breakdown spectrometer (ChemiCam) and successfully deployed the instrument from a remotely operated vehicle (ROV) to perform in situ multi-element analysis of both seawater and mineral deposits at depths of over 1000 m. The instrument consists of a long-nanosecond duration pulse-laser, a spectrometer and a high-speed camera. Power supply, instrument control and signal telemetry are provided through a ROV tether. The instrument has two modes of operation. In the first mode, the laser is focused directly into seawater and spectroscopic measurements of seawater composition are performed. In the second mode, a fiberoptic cable assembly is used to make spectroscopic measurements of mineral deposits. In this mode the laser is fired through a 4 m long fiber-optic cable and is focused onto the target's surface using an optical head and a linear stage that can be held by a ROV manipulator. In this paper, we describe the instrument and the methods developed to process its measurements. Exemplary measurements of both seawater and mineral deposits made during deployments of the device at an active hydrothermal vent field in the Okinawa trough are presented. Through integration with platforms such as underwater vehicles, drilling systems and subsea observatories, it is hoped that this technology can contribute to more efficient scientific surveys of the deep-sea environment.

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Section: Underwater Libs At High Pressuresupporting

confidence: 85%

Development of a deep-sea laser-induced breakdown spectrometer for in situ multi-element chemical analysis

Thornton

Takahashi

Sato

et al. 2015

Deep Sea Research Part I: Oceanographic Research Papers

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159

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“…Another paper reports well resolved emission lines obtained by SP LA of zinc plate in water at different pressures [99] and by using the acquisition gate delay of 400 ns from the laser pulse (see Fig. 8.15-left).…”

Section: Direct Analysis Of Submerged Solid Samplesmentioning

confidence: 97%

“…8.6), and so obtained spectra are considered insufficient for sample analyses. However, some recent papers [57,[95][96][97][98][99] indicate that until now considered mechanisms for fast SP LIBS signal quenching after LA in liquids, need further studies. In [95] images of the plasma after ablation of submerged copper with only 16 mJ pulses at 1064 nm, were clearly observable at delays of 1000 and 2000 ns for pulse durations of 20 and 150 ns respectively.…”

Section: Direct Analysis Of Submerged Solid Samplesmentioning

confidence: 99%

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LIBS Analysis of Liquids and of Materials Inside Liquids

Lazic

2014

Springer Series in Optical Sciences

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Abbreviations and Symbols CILaser induced plasma formation on or inside liquids is characterized by large energy losses due to liquid evaporation. Ablation of a liquid surface is followed by hydro-dynamical instabilities and splashing. Plasma generation inside bulk liquids is affected by the light absorption and scattering, and it is accompanied by intense pressure waves and successive vapor cavitation. Efficient LIBS analyses in presence of liquids require different considerations; the examples are reported and discussed in following. IntroductionLaser induced plasma formation has the irradiance threshold dependent on the sample density, and generally it progressively reduces when passing from gases, to liquids and then to solids. Excluding the losses along the beam path, this means that less laser energy is required for ablation of dry or submerged solid materials than for ablation of a liquid or for generating breakdown inside liquids. Plasma formation in presence of liquids is not efficient because a great portion of the laser energy is expended for the liquid vaporization; this strongly reduces the energy available for the plasma excitation. It has been estimated that about 75 % of the input radiation is consumed for vaporization during laser induced breakdown (LIB) inside water [1]. Furthermore, both water and organic solutions contain hydrogen, which contributes to a rapid thermalization and cooling of the formed plasma. Once the plasma is created in liquids, the high density and nearly incompressible medium strongly confines the plume; the corresponding effects on the plasma evolution and LIBS signal are recently reviewed [2]. Laser ablation (LA) of liquids by short, intense pulses is a complex process where the liquid surface is no longer in equilibrium with the surrounding vapor; this results in a very high net mass flux from the sample surface to the surrounding [3 and references therein]. The high mass flux increases the pressure at the target surface and so raises the boiling temperature. Once the normal boiling is established, the presence of volumetric energy densities slightly higher than that equivalent to the saturation temperature causes the formation and growth of a vapor bubble. If the deposition rate of volumetric energy density by a laser pulse exceeds the energy consumed by vaporization, the liquid is driven to a metastable state until the spinoidal temperature is reached. At this temperature, the liquid undergoes so called ''spinoidal decomposition'' where the entire superheated liquid volume separates into saturated liquid and vapor, which are ejected into atmosphere. This process occurs normally during LIBS sampling of a liquid surface. In case of water ablation it has been estimated that less than 50 % of the deposited energy transforms into vapor while the remaining part is consumed for ejection of droplets [3]. The energy loss on droplet expulsion i.e. splashing further degrades the LIBS signal.LIBS measurements are often performed on water solutions or inside the same. Laser intera...

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“…The excited atoms and ions emit specific wavelengths of light as they relax back to their ground state, which allows for simultaneous multi-element detection. LIBS is a promising tool for on-site chemical analysis and has been applied to the surveys of nuclear powers plants [1,2], planetary [3,4] and deep-sea explorations [5][6][7]. However, LIBS signals obtained underwater using a conventional single pulse method are significantly degraded compared to measurements in gaseous environments [8][9][10].…”

Section: Introductionmentioning

confidence: 99%

Calibration-free analysis of immersed brass alloys using long-ns-duration pulse laser-induced breakdown spectroscopy with and without correction for nonstoichiometric ablation

Takahashi

Thornton

Ohki³

et al. 2015

Spectrochimica Acta Part B: Atomic Spectroscopy

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a b s t r a c t Keywords:Laser-induced breakdown spectroscopy (LIBS) Calibration-free LIBS Liquid-phase laser ablation Quantitative analysis Long-pulse laser Long-ns-duration, single pulse laser-induced breakdown spectroscopy (LIBS) is known to be an effective method to observe well resolved spectra from samples immersed in water at high hydrostatic pressures. The aim of this study is to investigate whether the signals obtained using this method are suitable for quantitative analysis of chemical composition. Six certified brass alloys consisting of copper (Cu), zinc (Zn) and lead (Pb) were measured underwater using a laser pulse of duration 250 ns, and their compositions were determined using calibration-free LIBS (CF-LIBS) and corrected CF-LIBS (CCF-LIBS) methods. The mass fractions of Cu and Zn calculated using CF-LIBS showed better agreement with the certified values than those determined using CCF-LIBS, with relative errors of Cu 4.2 ± 3.3 % and Zn 7.2 ± 6.4 %. From the results, it can be said that the difference of preferential evaporation and ablation among elements does not need to be considered for underwater measurements with the long-pulse LIBS setup used in this work. While the results indicate that the CF-LIBS method can be applied for in situ quantitative analysis of major elements with concentrations N~10 %, the mass fractions determined for Pb, with concentrations b 5 % had large relative errors, suggesting that an alternative method is required to quantify minor elements.

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Effects of Pressure on the Optical Emissions Observed from Solids Immersed in Water Using a Single Pulse Laser

Cited by 60 publications

References 10 publications

Development of a deep-sea laser-induced breakdown spectrometer for in situ multi-element chemical analysis

Development of a deep-sea laser-induced breakdown spectrometer for in situ multi-element chemical analysis

LIBS Analysis of Liquids and of Materials Inside Liquids

Calibration-free analysis of immersed brass alloys using long-ns-duration pulse laser-induced breakdown spectroscopy with and without correction for nonstoichiometric ablation

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