Emission enhancement in laser-produced plasmas on preheated targets

Sanginés, R.; Sobral, H.; Álvarez‐Zauco, Edgar

doi:10.1007/s00340-012-5130-6

Cited by 36 publications

(22 citation statements)

References 29 publications

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“…3a and the per-unit inset show that for fixed laser energy the line intensity increases when the sample is cooled below room temperature, but on reaching 150 K target temperature the intensity stays more or less level as the target is further cooled. This trend disagrees with previous results obtained in high-temperature ambientair experiments that show that the line intensity diminishes when the target's temperature diminishes [15,16].…”

Section: Resultscontrasting

confidence: 93%

“…The figure shows that for fixed target temperature the intensity of the line is directly proportional to the laser energy. This behavior is similar to that observed in plasmas in ambient air at room temperature for which the line intensity also increases with laser energy [15]. The curves in Fig.…”

Section: Resultssupporting

confidence: 86%

“…They found that the intensity of the lines decreased when the target was cooled. This result seemingly matched the increasing trend observed in previous reports of intensification of the line emission when the target was heated several hundred degrees above room temperature [15,16]. The goal of the present work is to investigate whether this trend, i. e. decreasing intensity with decreasing temperature, effectively persists at cryogenic temperatures (down to 24 K) and also to explore other properties of the laser ablation plasma such as its continuum emission.…”

Section: Introductionsupporting

confidence: 88%

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Laser ablation of a metallic target under cryogenic conditions

et al. 2021

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The effect that the target's temperature has on the characteristics of an ablation plasma as it was cooled from room temperature down to ~ 20 K was investigated. The target was attached to the cold finger of a helium refrigerator, both operating in a vacuum environment for thermal insulation. The plasma was produced by focusing a nanosecond high-power laser onto the sample. A spectrometer and a monochromator were used to monitor both the line and the continuum emissions, with and without time resolution. It was found that, starting at room temperature, the intensity of the lines emitted steadily increased as the target was cooled down to 150-175 K and afterward remained level as the target was further cooled. Using the Boltzmann plot technique the excitation temperature was obtained and it was found that its mean value gradually increased as the target was cooled. The calculated electronic density, on the contrary, decreased with decreasing target temperature. Another effect noted was that the intensity of the continuum also varied with target temperature. We found that the continuum´s distribution does not match a free-free or a recombination source, but it does fit a blackbody one. By fitting Planck's formula to the continuum spectra the blackbody temperature was extracted and it was found to be within the 9400-13,300 K interval. By solving the heat-flow equation before plasma onset we demonstrate that the laser beam heats the sample's surface at a faster rate the cooler it is and that this peculiar behavior is the reason why the excitation temperature increases at cryogenic temperatures. This behavior is a consequence of the fact that the sample's specific heat varies by two orders of magnitude as it is cooled from room temperature to ~ 20 K.

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Section: Resultscontrasting

confidence: 93%

Section: Resultssupporting

confidence: 86%

Section: Introductionsupporting

confidence: 88%

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Laser ablation of a metallic target under cryogenic conditions

et al. 2021

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“…The air spark also heats the sample surface inducing changes in its optical properties [41,43,44]. In a previous work [41], we observed that the temperature near the sample surface in the pre-ablative configuration exceeds the Al target fusion value for up to 40 μs.…”

Section: Pre-ablation Schemementioning

confidence: 96%

Optimal emission enhancement in orthogonal double-pulse laser-induced breakdown spectroscopy

Sanginés

Contreras

Sobral

et al. 2015

Spectrochimica Acta Part B: Atomic Spectroscopy

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“…Its acceptable cost and excellent mechanical stability make nanosecond laser more popular as a pump source in LIBS equipment. In order to improve the sensitivity and accuracy of nanosecond LIBS (ns-LIBS), many methods have been developed, such as dual-pulse excitation, spatial connement, microwave-assisted LIBS ame-enhanced LIBS, [14][15][16][17][18][19][20][21][22] etc. In these methods, dual-pulse excitation plays an important role and has proved to be a very effective way to improve the analytical performance of ns-LIBS.…”

Section: Introductionmentioning

confidence: 99%