This work was funded through U.S. Department of Energy, Office of Science.

1. Laser System
<ol>
	<li>Use laser pulses produced by a Q-switched Nd:YAG laser operating at 1,064 nm and at 10 Hz.</li>
	<li>Focus the laser pulses onto the sample with a 75 mm focal length lens.</li>
	<li>Collect the plasma light with an optical fiber pointed at and placed near the plasma formed on the sample.</li>
	<li>Use an Echelle spectrograph/ICCD to spectrally resolve and record the LIBS spectrum.</li>
	<li>Operate the ICCD in both non-gated and gated modes using a gain of 125.</li>
	<li>Use a 0 &#956;sec time...

<ol>
	<li>Song, K., Lee, Y., Sneddon, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Recent+developments+in+instrumentation+for+laser+induced+breakdown+spectroscopy.">Recent developments in instrumentation for laser induced breakdown spectroscopy.</a> Appl. Spec. Rev. 37 (1), 89-117 (2002).</li><li>Yamamoto, K. Y., Cremers, D. A., Foster, L. E., Ferris, M. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Detection+of+Metals+in+the+Environment+Using+a+Portable+Laser-Induced+Breakdown+Spectroscopy+Instrument.">Detection of Metals in the Environment Using a Portable Laser-Induced Breakdown Spectroscopy Instrument.</a> Appl. Spec. 50 (2), 222-233 (1996).</li><li>Cu&#241;at, J., Fortes, F. J., Cabal&#237;n, L. M., Carrasco, F., Sim&#243;n, M. D., Laserna, J. 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J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effect+of+Sampling+Geometry+on+Elemental+Emissions+in+Laser-Induced+Breakdown+Spectroscopy.">Effect of Sampling Geometry on Elemental Emissions in Laser-Induced Breakdown Spectroscopy.</a> Appl. Spec. 50 (12), 1483-1499 (1996).</li><li>Harmon, R. S., DeLucia, F. C., McManus, C. E., McMillan, N. J., Jenkins, T. F., Walsh, M. E., Miziolek, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Laser-induced+breakdown+spectroscopy+-+An+emerging+chemical+sensor+technology+for+real-time+field-portable,+geochemical,+mineralogical,+and+environmental+applications.">Laser-induced breakdown spectroscopy - An emerging chemical sensor technology for real-time field-portable, geochemical, mineralogical, and environmental applications.</a> Appl. Geochem. 21 (5), 730-747 (2006).</li><li>Schill, A. W., Heaps, D. A., Stratis-Cullum, D. N., Arnold, B. R., Pellegrino, P. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Characterization+of+near-infrared+low+energy+ultra-short+laser+pulses+for+portable+applications+of+laser+induced+breakdown+spectroscopy.">Characterization of near-infrared low energy ultra-short laser pulses for portable applications of laser induced breakdown spectroscopy.</a> Opt. Express. 15 (21), 14044-14056 (2007).</li><li>Fortes, F. J., Laserna, J. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+development+of+fieldable+laser-induced+breakdown+spectrometer:+No+limits+on+the+horizon.">The development of fieldable laser-induced breakdown spectrometer: No limits on the horizon.</a> Spectrochim. 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R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Laser-induced+breakdown+spectroscopy:+Time-integrated+applications.">Laser-induced breakdown spectroscopy: Time-integrated applications.</a> J. Plasma Chem. Plasma Proc. 1 (3), 281-293 (1981).</li><li>Mueller, M., Gornushkin, I. B., Florek, S., Mory, D., Panne, U. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Approach+to+Detection+in+Laser-Induced+Breakdown+Spectroscopy.">Approach to Detection in Laser-Induced Breakdown Spectroscopy.</a> Anal. Chem. 79 (12), 4419-4426 (2007).</li><li>Fan, C., Longtin, J. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Modeling+Optical+Breakdown+in+Dielectrics+During+Ultrafast+Laser+Processing.">Modeling Optical Breakdown in Dielectrics During Ultrafast Laser Processing.</a> Appl. Opt. 40 (18), 3124-3131 (2001).</li><li>ANSI Z-136.5. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> American National Standard for Safe Use of Lasers in Educational Institutions. , (2009).</li><li>. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Compendium of Chemical Terminology. , (1997).</li><li>Cremers, D. A., Radziemski, L. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Handbook of Laser-Induced Breakdown Spectroscopy. , (2006).</li><li>Griem, H. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Spectral Line Broadening by Plasmas. , (1974).</li><li>Ashkenazy, J., Kipper, R., Caner, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Spectroscopic+Measurements+of+Electron+Density+of+Capillary+Plasma+Based+on+Stark+Broadening+of+Hydrogen+Lines.">Spectroscopic Measurements of Electron Density of Capillary Plasma Based on Stark Broadening of Hydrogen Lines.</a> Phys. Rev. A. 43 (10), 5568-5574 (1991).</li></ol>

The authors do not have anything to disclose.

When comparing non-gated and gated detection modes, the detection limit data show that the gated detection mode allowed for detection of all of the elements including those that were not seen using higher laser energies in non-gated detection mode. Using gated detection, the initial high background from the formation of the plasma is not observed and the background is decreased showing the elemental emission better resolved. Furthermore, the detection limits were slightly lower using gated detection.
<p class="jove_c...

Laser-induced breakdown spectroscopy (LIBS) is a simple method of elemental analysis that uses a laser-generated spark as the excitation source. The laser pulse is focused onto a surface that heats, ablates, atomizes and ionizes the surface material resulting in the formation of plasma. The plasma light is spectrally resolved and detected and elements are identified by their spectral signatures. If properly calibrated, LIBS can provide quantitative results. LIBS can analyze solids, gases, and liquids with little or no sample preparation.1 These characteristics make it ideal for analyses that cannot be carried out in the laboratory.
Currently, LIBS is being studied for many different applications especially those that require field-based measurements for quantification.1-8 This requires the development of LIBS instrumentation using rugged and compact components suitable for a field-based system. In most cases, these components will not have the full capabilities of laboratory-based instrumentation, thereby compromising the analysis performance. LIBS results are dependent on laser pulse parameters and other measurement conditions that include sampling geometry, surrounding atmosphere, and the use of gated or non-gated detection.9-12 For field-based LIBS instrumentation, two important factors to consider are the pulse energy and the use of gated versus non-gated detection. These two factors determine to a large extent the cost, size, and complexity of the LIBS instrument. Small, ruggedly built lasers that can generate pulses from 10-50 mJ at repetition rates of 0.3-10 Hz are commercially available and would be highly advantageous to use. Therefore, it is important to know what, if any, loss in detection capabilities will result from the use of these lasers. The pulse energy is a key parameter for LIBS as it determines the amount of material ablated and vaporized and the excitation characteristics of the plasma. In addition, the use of gated detection can increase the cost of the LIBS system; as a result, it is imperative to determine the differences between spectra and detection capabilities using gated and non-gated detection.
Recently, a study was performed comparing gated detection to non-gated detection for minor elements found in steel. The results showed that the detection limits were comparable if not better for non-gated detection.12 One important characteristic of LIBS is that the technique experiences physical and chemical matrix effects. An example of the former is that the laser pulse couples more efficiently with conducting/metal surfaces than non-conducting surfaces.13 For this study, we wanted to determine the effects of pulse energy and timing parameters for non-conducting materials like soil simulants.
Although, field portable LIBS instruments have been developed and used for some applications, a comprehensive study on the detection capabilities has not been performed comparing higher energy and gated systems to lower energy and non-gated systems using soil simulants. This study focuses on laser pulse energy and timing parameters for determination of trace elements in complex matrices. The laser pulse energy ranged from 10 to 100 mJ to obtain a comparison between lower and higher energies. A comparison of the use of gated versus non-gated detection was also performed over the same energy range.

<table border="1">
		<tbody>
		 <tr>
			<td></td>
			<td></td>
			<td></td>
			<td>Equipment</td>
		 </tr>
		 <tr>
			<td>Nd:YAG laser</td>
			<td>Continuum</td>
			<td>Surelite II</td>
			<td></td>
		 </tr>
		 <tr>
			<td>Echelle spectrograh/ICCD</td>
			<td>Catalina/Andor</td>
			<td>SE200/iStar</td>
			<td></td>
		 </tr>
		 <tr>
			<td>Digital delay generator</td>
			<td>BNC</td>
			<td>Model 575-4C</td>
			<td></td>
		 </tr>
		 <tr>
			<td>Hydraulic Press</td>
			<td>Carver</td>
			<td>Model-C</td>
			<td></td>
		 </tr>
		 <tr>
			<td>31-mm pellet die</td>
			<td>Carver</td>
			<td>3902</td>
			<td></td>
		 </tr>
		 <tr>
			<td>Power meter indictor model</td>
			<td>Scientech, Inc.</td>
			<td>Model number: AI310D</td>
			<td></td>
		 </tr>
		 <tr>
			<td>Power meter detector model</td>
			<td>Scientech, Inc.</td>
			<td>Model number: AC2501S</td>
			<td></td>
		 </tr>
		 <tr>
			<td>Oscilloscope</td>
			<td>Tektronix</td>
			<td>MSO 4054</td>
			<td></td>
		 </tr>
		 <tr>
			<td>Optical fiber</td>
			<td>Ocean Optics</td>
			<td>QP1000-2-UV-VIS</td>
			<td></td>
		 </tr>
		 <tr>
			<td>Lens kit (this kit contains the 75 mm f.l. lens)</td>
			<td>CVI Optics</td>
			<td>LK-24-C-1064</td>
			<td></td>
		 </tr>
		 <tr>
			<td></td>
			<td></td>
			<td></td>
			<td>Reagent/Material list</td>
		 </tr>
		 <tr>
			<td>Synthetic silicate sample</td>
			<td>Brammer Standard Company</td>
			<td>GBW 07704 </td>
			<td></td>
		 </tr>
		 <tr>
			<td>Synthetic silicate sample</td>
			<td>Brammer Standard Company</td>
			<td>GBW 07705 </td>
			<td></td>
		 </tr>
		 <tr>
			<td>Synthetic silicate sample</td>
			<td>Brammer Standard Company</td>
			<td>GBW 07706</td>
			<td></td>
		 </tr>
		 <tr>
			<td>Synthetic silicate sample</td>
			<td>Brammer Standard Company</td>
			<td>GBW 07708</td>
			<td></td>
		 </tr>
		 <tr>
			<td>Synthetic silicate sample</td>
			<td>Brammer Standard Company</td>
			<td>GBW 07709</td>
			<td></td>
		 </tr>
		 <tr>
			<td>Aluminum caps (for pressing synthetic silicate samples)</td>
			<td>SCP Science</td>
			<td>040-080-001</td>
			<td></td>
		 </tr>
		</tbody>
 </table>

dependence of laser-induced breakdown spectroscopy results on pulse energies and timing parameters using soil simulants

The dependence of some LIBS detection capabilities on lower pulse energies (&lt;100 mJ) and timing parameters were examined using synthetic silicate samples. These samples were used as simulants for soil and contained minor and trace elements commonly found in soil at a wide range of concentrations. For this study, over 100 calibration curves were prepared using different pulse energies and timing parameters; detection limits and sensitivities were determined from the calibration curves. Plasma temperatures were also measured using Boltzmann plots for the various energies and the timing parameters tested. The electron density of the plasma was calculated using the full-width half maximum (FWHM) of the hydrogen line at 656.5 nm over the energies tested. Overall, the results indicate that the use of lower pulse energies and non-gated detection do not seriously compromise the analytical results. These results are very relevant to the design of field- and person-portable LIBS instruments.

Effect of laser pulse energy and detection modes on detection capabilities. LIBS spectra of the synthetic silicate samples were recorded using gated and non-gated detection over the range of laser pulse energies tested. Over 100 calibration curves were constructed from these data to evaluate the effect of the laser pulse energy. Calibration curves were prepared by (1) using the area under the analyte peak and (2) by ratioing the area of the analyte peak to the area of the iron peak at 405.58 nm. The iron...

Watch this Scientific Journal Video about Dependence of Laser-induced Breakdown Spectroscopy Results on Pulse Energies and Timing Parameters Using Soil Simulants at JoVE.com

Dependence of Laser-induced Breakdown Spectroscopy Results on Pulse Energies and Timing Parameters Using Soil Simulants

LIBS detection capabilities on soil simulants were tested using a range of pulse energies and timing parameters. Calibration curves were used to determine detection limits and sensitivities for different parameters. Generally, the results showed that there was not a significant reduction in detection capabilities using lower pulse energies and non-gated detection.

The  dependence of some LIBS detection capabilities on lower pulse energies (&lt;100  mJ) and timing parameters were examined using synthetic silicate ...

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11.2K 조회수.  Alvernia University.  토양에 닮은 LIBS 검출 기능은 펄스 에너지 및 타이밍 파라미터의 범위를 사용하여 시험 하였다. 교정 곡선은 다른 매개 변수에 대한 검출 한계 및 감도를 결정하는 데 사용 하였다. 일반적으로, 결과는 낮은 펄스 에너지 및 비 게이트 탐지를 사용하여 탐지 기능에 상당한 감소가없는 것으로 나타났다. 