The authors thank Mr. J. O. Hornkohl for interest and discussion on computation of diatomic molecular line strengths. This work is in part supported by the Center for Laser Applications at the University of Tennessee Space Institute.

1. Optical System Setup
<ol>
	<li>Place a beam splitter at the exit of the laser, allowing the 1,064 nm wavelength light to pass through and to reflect all other transient laser radiation into a beam dump.</li>
	<li>Place a high-speed PIN photodiode detector to record a portion of the laser radiation reflected off the beam splitter. Connect this detector to the oscilloscope with coaxial cable to monitor the optical pulse with respect to triggering by the function generator and occurrence of the Q-switching in the Nd:YAG laser device.</li>
	<li>Align three IR reflective mirrors to position the beam parallel to the slit of the spectrometer.</li>
	<li>Position a lens above translational stage to focus the beam in order to generate optical breakdown plasma parallel to the spectrometer slit. Align two quartz lenses for the purpose of imaging the plasma onto the slit. The two focusing lenses optimally match the spectrometer design, meaning the final lens has an aperture to accomplish a f# identical with the f# of the spectrometer&#39;s internal optics.</li>
	<li>For measurements above 380 nm, position a cut-on filter between the two lenses for the purpose of blocking radiation below 380 nm. The cut-on filter suppresses possible UV contributions (due to 2nd order of grating) to the measured spectra.</li>
</ol>
2. Data Acquisition Setup
<ol>
	<li>Connect a wave-form function generator providing a triangular wave at 50 Hz to a custom built divide-by-five circuit to obtain 10 Hz. The optical multichannel analyzer (OMA) is operated at 50 Hz and the flash lamps of the Nd:YAG laser are synchronously operated at 10 Hz. One can use an ICCD in place of the OMA, operating&#160;synchronously at the rate of the pulsed laser radiation&#160;as well.</li>
	<li>Connect one of the outputs of the custom built divide-by-five circuit to a digital delay generator. Use one output to synchronize the Nd:YAG flash lamps and another output to control the triggers of the linear diode array intensifier and optical multichannel analyzer. Again, instead of the intensified linear diode array and OMA one can use an ICCD.</li>
	<li>Relay the adjustable trigger output of the laser device to an oscilloscope and to a pulse generator. The oscilloscope will be used to monitor when the pulsed laser radiation will be available for optical breakdown generation or laser ablation.</li>
	<li>Connect the high voltage output of the digital pulse generator to the intensified linear diode array.</li>
	<li>Connect the other output of the pulse generator to the oscilloscope.</li>
	<li>Connect the intensified linear diode array output to the OMA.</li>
</ol>
3. Synchronization and Measurement
<ol>
	<li>Set the wave-form function generator to output a triangle pulse operating at 50&#177;1 Hz. This function generator provides the master frequency. A custom built divide-by-five circuit and a digital delay generator are used for accurate synchronization.</li>
	<li>Initiate water cooling system and power supply for laser device. Activate laser.</li>
	<li>Determine the time for laser radiation to travel from the exit aperture of the Nd:YAG laser to the area in front of the spectrometer slit as follows: Measure the distance of the light path and compute the&#160;transit time using the speed-of-light. Account for this transit time in setting the gate delay time in next step.</li>
	<li>On the digital pulse generator, set the gate width for the measurement and the delay time from optical breakdown or laser ablation pulse,&#160;and use the oscilloscope to monitor the delay time. The delay time will determine how long to wait for data collection after breakdown occurs. The gate width determines how long the diode array is exposed to plasma radiation.</li>
	<li>Generate optical breakdown in air and/or place a sample on the translational stage such that ablation will occur. Image the microplasma onto the spectrometer slit.</li>
	<li>Begin measurements and record data with the intensified linear diode array and optical multichannel analyzer (or with an ICCD).</li>
</ol>
4. Wavelength Calibration
<ol>
	<li>Record spectra from standard calibration lamps: neon, mercury, and hydrogen lamps. Use the experimental arrangement with lamps put at the place where plasma was generated.</li>
	<li>Using the known wavelengths from lamps, perform a linear or cubic fit to obtain the pixel-wavelength correspondence. The purpose of an accurate calibration is to correct for nonlinearities that are usually associated with measurement of spectra.</li>
	<li>Repeat calibrations for H, C2, CN, and TiO spectral regions of interest.</li>
</ol>
5. Intensity Calibration
<ol>
	<li>Turn on a tungsten calibration lamp and wait for it to warm up.</li>
	<li>Use an optical pyrometer to measure the temperature of the active lamp.</li>
	<li>Use the experimental arrangement to record the spectrum of the active lamp.</li>
	<li>Compute a blackbody curve from Plank&#39;s radiation law using the measured temperature as an input parameter.</li>
	<li>Fit the computed curve to the spectrum of the active lamp. Determine the factors by which the recorded intensities from the computed curve. Apply those factors to correct recorded spectra for wavelength-dependent sensitivity of the detector.</li>
	<li>Repeat this for each region the spectrometer was used.</li>
</ol>
6. Data Transfer
<ol>
	<li>Prepare medium for file transfers.</li>
	<li>For each data measurement, record it onto the medium.</li>
	<li>Take this medium and upload the files on it to a work computer.</li>
</ol>
7. File Preparation
<ol>
	<li>For each file, parse it into sections, one containing recorded data, and the others specifying starting wavelength and average wavelength shift per data point.</li>
	<li>Use these sections to create a new file to match wavelengths with recorded data.</li>
</ol>
8. Diatomic Molecular Analysis
<ol>
	<li>Select the wavelength file and corresponding line strength file.</li>
	<li>Select the baseline offset.
	<ol>
		<li>Set whether the offset is constant, linear, or quadratic.</li>
		<li>Set the corresponding coefficients to either fixed or variable values.</li>
	</ol>
	</li>
	<li>Set the resolution and temperature, both of which can be either fixed or varied.</li>
	<li>Set the tolerance of fit for the synthetic spectra to be fit to the measured spectra.</li>
	<li>Fit the computed to the experimental spectra using a Nelder-Mead algorithm.</li>
	<li>Using the best fitting parameters of the computed spectra for each measurement, infer the microplasma parameters observed at the various time delays and gate widths used.</li>
</ol>

<ol>
	<li>Miziolek, A. W., Palleschi, V., Schechter, I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Laser Induced Breakdown Spectroscopy. , (2006).</li><li>Cremers, D. E., 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>Singh, J. P., Thakur, S. N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Laser Induced Breakdown Spectroscopy. , (2007).</li><li>Hahn, D. W., Omenetto, N. <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+(LIBS),+Part+I:+review+of+basic+diagnostics+and+plasma-particle+iterations:+still-challenging+issues+within+the+analytical+plasma+community.">Laser-induced breakdown spectroscopy (LIBS), Part I: review of basic diagnostics and plasma-particle iterations: still-challenging issues within the analytical plasma community.</a> Appl. Spectrosc. 64, (2010).</li><li>Hahn, D. W., Omenetto, N. <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+(LIBS),+Part+II:+review+of+instrumental+and+methodological+approaches+to+material+analysis+and+applications+to+different+fields.">Laser-induced breakdown spectroscopy (LIBS), Part II: review of instrumental and methodological approaches to material analysis and applications to different fields.</a> Appl. Spectrosc. 66, 347 (2012).</li><li>Parigger, C. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Atomic+and+molecular+emissions+in+laser-induced+breakdown+spectroscopy.">Atomic and molecular emissions in laser-induced breakdown spectroscopy.</a> Spectrochim. Acta Part B. 79, 4-16 (2013).</li><li>Konjevi&#263;, N., Lesage, A., Fuhr, J. R., Wiese, W. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Experimental+Stark+widths+and+shifts+for+spectral+lines+of+neutral+and+ionized+atoms.">Experimental Stark widths and shifts for spectral lines of neutral and ionized atoms.</a> J. Phys. Chem. Ref. Data. 31, 819-927 (2002).</li><li>Oks, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Stark+broadening+of+hydrogen+and+hydrogen-like+spectral+lines+in+plasmas:+the+physical+insight.">Stark broadening of hydrogen and hydrogen-like spectral lines in plasmas: the physical insight.</a> Alpha Science Int. , (2006).</li><li>Parigger, C. G., Dackman, M., Hornkohl, J. O. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Time-resolved+spectroscopy+measurements+of+hydrogen-alpha,+-beta,+and+-gamma+emissions.">Time-resolved spectroscopy measurements of hydrogen-alpha, -beta, and -gamma emissions.</a> Appl. Opt. 47, (2008).</li><li>Parigger, C. G., Oks, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hydrogen+Balmer+series+spectroscopy+in+laser-induced+breakdown+plasmas.">Hydrogen Balmer series spectroscopy in laser-induced breakdown plasmas.</a> Int. Rev. Atom. Mol. Phys. 1, 13-23 (2010).</li><li>Lucena, A. D., Tobaria, L. M., 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=New+challenges+and+insights+in+the+detection+and+spectral+identification+of+organic+explosives+by+laser+induced+breakdown+spectroscopy.">New challenges and insights in the detection and spectral identification of organic explosives by laser induced breakdown spectroscopy.</a> Spectrochim. Acta Part B. 66 (1), 12-20 (2011).</li><li>Swafford, L. D., Parigger, C. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Measurement+of+hydrogen+Balmer+Series+lines+following+laser-induced+optical+breakdown+in+laboratory+air.">Measurement of hydrogen Balmer Series lines following laser-induced optical breakdown in laboratory air.</a> Accepted, Int. Rev. Atom. Mol. Phys. 4 (1), (2013).</li><li>Hornkohl, J. O., Nemes, L., Parigger, C. G., Nemes, L., Irle, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Spectroscopy+of+Carbon+Containing+Diatomic+Molecules.">Spectroscopy of Carbon Containing Diatomic Molecules.</a> Spectroscopy, Dynamics and Molecular Theory of Carbon Plasmas and Vapor. , 113-165 (2011).</li><li>Parigger, C., Hornkohl, J. O. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Diatomic+molecular+spectroscopy+with+standard+and+anomalous+commutators.">Diatomic molecular spectroscopy with standard and anomalous commutators.</a> Int. Rev. Atom. Mol. Phys. 1, 25-43 (2010).</li><li>Parigger, C. G., Hornkohl, J. O. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Computation+of+AlO+emission+spectra.">Computation of AlO emission spectra.</a> Spectrochim. Acta Part A. 81, 404-411 (2011).</li><li>Hermann, J., Peronne, A., Dutouquet, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Analysis+of+the+TiO-&#947;+System+for+temperature+measurements+in+laser-induced+plasma.">Analysis of the TiO-&#947; System for temperature measurements in laser-induced plasma.</a> J. Phys. B: At. Mol. Opt. Phys. 34, 153-164 (2001).</li><li>Woods, A. C., Parigger, C. G., Hornkohl, J. O. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Measurements+and+analysis+of+titanium+monoxide+spectra+in+laser-induced+plasma.">Measurements and analysis of titanium monoxide spectra in laser-induced plasma.</a> Opt. Lett. 37, 5139-5141 (2012).</li><li>Witte, M. J., Parigger, C. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Measurement+and+analysis+of+carbon+Swan+spectra+following+laser-induced+optical+breakdown+in+air.">Measurement and analysis of carbon Swan spectra following laser-induced optical breakdown in air.</a> Accepted, Int. Rev. Atom. Mol. Phys. 4 (1), (2013).</li><li>Surmick, D. M., Parigger, C. G., Woods, A. C., Donaldson, A. B., Height, J. L., Gill, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Analysis+of+emission+Spectra+of+Aluminum+Monoxide+in+a+Solid+Propellant+Flame.">Analysis of emission Spectra of Aluminum Monoxide in a Solid Propellant Flame.</a> Int. Rev. Atom. Mol. Phys. 3 (2), 2-137 (2012).</li><li>Woods, A. C., Parigger, C. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Time-resolved+Temperature+Inferences+Utilizing+the+TiO+A3&#966;&#8594;X3&#916;+Band+in+Laser-induced+Plasma.">Time-resolved Temperature Inferences Utilizing the TiO A3&#966;&#8594;X3&#916; Band in Laser-induced Plasma.</a> Int. Rev. Atom. Mol. Phys. 3 (2), 103-111 (2012).</li></ol>

All authors declare that they have no competing financial interests.

The time resolved measurement protocol and representative results are further discussed here. It is important to synchronize the laser pulses, generated at a rate of 10 Hz, with the 50 Hz operating frequency of the intensified linear diode array and OMA (or ICCD). Furthermore, accurate timing of laser pulses and opening of the gate of the intensified linear diode array (or alternatively ICCD) is essential. The wave generator,&#160;indicated in the experimental schematic, is used to synchronize the laser pulses and intens...

Laser-induced breakdown spectroscopy (LIBS) techniques1-5&#160;have applications in atomic6-12 and molecular studies of plasma13-20 generated with laser radiation. Time-resolved spectroscopy is essential for determination of the transient characteristics of the plasma. Temperature and electron density, to name but two plasma parameters, can be measured provided a reasonable theoretical model of the plasma breakdown is available. Separation of free-electron radiation from atomic and molecular emissions&#160;allows us to accurately explore transient phenomena. By focusing on a specific temporal window, one can &#8220;freeze&#8221; plasma decay and thereby obtain accurate spectroscopic fingerprints. LIBS has a variety of applications&#160;and recently interest in LIBS-diagnostics shows a considerable increase when measured by the number of researchers publishing in the field. Pico- and femtosecond generated microplasma is of ongoing research interest, however, historically experimental LIBS arrangements utilize nanosecond laser radiation.
Figure 1 displays a typical experimental arrangement for laser-induced breakdown spectroscopy. For this protocol, the functional breakdown energy for the initial beam is on the order of 75 mJ pulse, at the infrared wavelength of 1,064 nm. This pulse energy can be adjusted as needed. The plasma is dispersed by the spectrometer and measured with an intensified linear diode array and OMA or, alternatively, imaged onto an Intensified 2-dimensional Charge&#160;Coupled&#160;Device (ICCD). Figure 2 illustrates the timing diagram for time-resolved experiments: synchronization of pulsed laser radiation with readout, laser pulse trigger, laser fire, and gate-open delay.
Successful time-resolved spectroscopy requires various calibration procedures. These procedures include wavelength calibration, background correction, and most importantly, sensitivity correction of the detector. Sensitivity corrected data are important for the comparison of measured and modeled spectra. For an increase of signal-to-noise ratio, multiple laser-induced breakdown events are recorded.

<table border="0" cellpadding="0" cellspacing="0" width="573">
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	<tbody>
		<tr height="80">
			<td height="80" style="height:80px;width:216px;">Custom Box</td>
			<td style="width:71px;">UTSI</td>
			<td style="width:119px;">None</td>
			<td style="width:167px;">Signal divider and conditioner. An oscilloscope can be used in place of this</td>
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		<tr height="20">
			<td height="20" style="height:20px;width:216px;"></td>
			<td style="width:71px;"></td>
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			<td height="80" style="height:80px;width:216px;">Four Channel Digital Delay/Pulse Generator</td>
			<td style="width:71px;">Stanford Research Systems, Inc.</td>
			<td style="width:119px;">Model DG535</td>
			<td style="width:167px;">Companies: Tequipment, diyAudio</td>
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			<td style="width:167px;"></td>
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		<tr height="100">
			<td height="100" style="height:100px;width:216px;">Four Channel Color Digital Phosphor Oscilloscope</td>
			<td style="width:71px;">Tektronix</td>
			<td style="width:119px;">TDS 3054</td>
			<td style="width:167px;">500 MHz - 5 GS/sec, Companies: Amazon, Tektronix, Fluke, Agilent Technologies, Pico Technology</td>
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			<td height="60" style="height:60px;width:216px;">Wavetek FG3C Function Generator</td>
			<td style="width:71px;">Wavetek</td>
			<td style="width:119px;">FG3C</td>
			<td style="width:167px;">Companies: Tequipment, Stanford Research Systems, BK Precision</td>
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			<td style="width:167px;"></td>
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		<tr height="100">
			<td height="100" style="height:100px;width:216px;">Nd:YAG Laser</td>
			<td style="width:71px;">Quanta-Ray</td>
			<td style="width:119px;">DCR-2A(10) PS</td>
			<td style="width:167px;">Laser radiation, Class IV.&#160; Companies: Lambda Photometrics, Continuum, Ellipse, Newport</td>
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		<tr height="20">
			<td height="20" style="height:20px;width:216px;"></td>
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			<td style="width:167px;"></td>
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		<tr height="80">
			<td height="80" style="height:80px;width:216px;">Si Biased Detector</td>
			<td style="width:71px;">Thorlabs</td>
			<td style="width:119px;">DET10A/M</td>
			<td style="width:167px;">200-1,100 nm, with ND10A reflective filter. Companies: Canberra, Edmund Optics</td>
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			<td style="width:167px;"></td>
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		<tr height="40">
			<td height="40" style="height:40px;width:216px;">Nd:YAG Laser Line Mirror, 1,064 nm</td>
			<td style="width:71px;">Thorlabs</td>
			<td style="width:119px;">NB1-K13</td>
			<td style="width:167px;">Companies: Edmund Optics, Newport</td>
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			<td style="width:71px;"></td>
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		<tr height="40">
			<td height="40" style="height:40px;width:216px;">1 in Fused Silica Bi-Convex Lens, uncoated</td>
			<td style="width:71px;">Newport</td>
			<td style="width:119px;">SBX031</td>
			<td style="width:167px;">Companies: Edmund Optics, Thorlabs</td>
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		<tr height="60">
			<td height="60" style="height:60px;width:216px;">2 in Fused Silica Plano-Convex lens, uncoated</td>
			<td style="width:71px;">Newport</td>
			<td style="width:119px;">SPX049</td>
			<td style="width:167px;">Convex lens, f/4.&#160; Companies: Edmund Optics, Thorlabs</td>
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			<td style="width:167px;"></td>
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			<td height="100" style="height:100px;width:216px;">Spectrograph</td>
			<td style="width:71px;">Instruments S.A. division Jobin-Yvon</td>
			<td style="width:119px;">HR 640</td>
			<td style="width:167px;">Companies: Andor, Newport, Horiba</td>
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			<td height="100" style="height:100px;width:216px;">Manual and electronic controller for Spectrograph</td>
			<td style="width:71px;">Instruments S.A. division Jobin-Yvon</td>
			<td style="width:119px;">Model 980028</td>
			<td style="width:167px;">Manual and electronic controller for Spectrograph</td>
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			<td height="40" style="height:40px;width:216px;">Mega 4000</td>
			<td style="width:71px;">Mega</td>
			<td style="width:119px;">Model 129709</td>
			<td style="width:167px;">Computer interface for Spectrograph</td>
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		<tr height="40">
			<td height="40" style="height:40px;width:216px;">Gateway 2000 Crystal Scan 1024 monitor</td>
			<td style="width:71px;">Gateway</td>
			<td style="width:119px;">PMV14AC</td>
			<td style="width:167px;">Monitor for computer interface</td>
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			<td height="20" style="height:20px;width:216px;"></td>
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			<td style="width:167px;"></td>
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		<tr height="80">
			<td height="80" style="height:80px;width:216px;">20 MHz Oscilloscope</td>
			<td style="width:71px;">BK Precision</td>
			<td style="width:119px;">Model 2125</td>
			<td style="width:167px;">Companies: Amazon, Tektronix, Fluke, Agilent Technologies, Pico Technology</td>
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		<tr height="20">
			<td height="20" style="height:20px;width:216px;"></td>
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			<td style="width:119px;"></td>
			<td style="width:167px;"></td>
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		<tr height="100">
			<td height="100" style="height:100px;width:216px;">6040 Universal Pulse Generator</td>
			<td style="width:71px;">Berkeley Nucleonics Corporation</td>
			<td style="width:119px;">Model 6040</td>
			<td style="width:167px;">Companies: Agilent Technologies, Tektronix, Quantum Composers</td>
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		<tr height="100">
			<td height="100" style="height:100px;width:216px;">Separate component to 6040 Universal Pulse Generator</td>
			<td style="width:71px;">Berkeley Nucleonics Corporation</td>
			<td style="width:119px;">Model 202 H</td>
			<td style="width:167px;">Separate component to 6040 Universal Pulse Generator</td>
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			<td style="width:71px;"></td>
			<td style="width:119px;"></td>
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		<tr height="80">
			<td height="80" style="height:80px;width:216px;">ICCD Camera</td>
			<td style="width:71px;">EG&#38;G Parc</td>
			<td style="width:119px;">Model 46113</td>
			<td style="width:167px;">Companies: Andor, Standford Computer Optics, LaVision, Hamamatsu</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:216px;"></td>
			<td style="width:71px;"></td>
			<td style="width:119px;"></td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="100">
			<td height="100" style="height:100px;width:216px;">OMA III</td>
			<td style="width:71px;">EG&#38;G Parc</td>
			<td style="width:119px;">Model 1460</td>
			<td style="width:167px;">Spectral data acquisition and analysis. Unit discontinued, replaced by software installed on computers.</td>
		</tr>
	</tbody>
</table>

measurement and analysis of atomic hydrogen and diatomic molecular alo, c2, cn, and tio spectra following laser-induced optical breakdown

In this work, we present time-resolved measurements of atomic and diatomic spectra following laser-induced optical breakdown. A typical LIBS arrangement is used. Here we operate a Nd:YAG laser at a frequency of 10 Hz at the fundamental wavelength of 1,064 nm. The 14 nsec pulses with anenergy of 190 mJ/pulse are focused to a 50 &#181;m spot size to generate a plasma from optical breakdown or laser ablation in air. The microplasma is imaged onto the entrance slit of a 0.6 m spectrometer, and spectra are recorded using an 1,800 grooves/mm grating an intensified linear diode array and optical multichannel analyzer (OMA) or an ICCD. Of interest are Stark-broadened atomic lines of the hydrogen Balmer series to infer electron density. We also elaborate on temperature measurements from diatomic emission spectra of aluminum monoxide (AlO), carbon (C2), cyanogen (CN), and titanium monoxide (TiO).
The experimental procedures include wavelength and sensitivity calibrations. Analysis of the recorded molecular spectra is accomplished by the fitting of data with tabulated line strengths. Furthermore, Monte-Carlo type simulations are performed to estimate the error margins. Time-resolved measurements are essential for the transient plasma commonly encountered in LIBS.

LIBS utilizes pulsed laser radiation to sufficiently ionize a sample to form plasma. Laser-induced breakdown of gaseous substances will create plasma that is centered about the focal region of the excitation beam, while laser ablation on solid surfaces will produce plasma above the sample&#39;s surface. The plasma is generated by focusing the optical radiation on the order of 100 GW/cm2 for nanosecond breakdown pulses. To produce laser ablation plasma, typically 1 GW/cm2 is more than sufficient. The...

Watch this Scientific Journal Video about Measurement and Analysis of Atomic Hydrogen and Diatomic Molecular AlO, C2, CN, and TiO Spectra Following Laser-induced Optical Breakdown at JoVE.com

Measurement and Analysis of Atomic Hydrogen and Diatomic Molecular AlO, C2, CN, and TiO Spectra Following Laser-induced Optical Breakdown

Time-resolved atomic and diatomic molecular species are measured using LIBS. The spectra are collected at various time delays following the generation of optical breakdown plasma with Nd:YAG laser radiation&#160;and are analyzed to infer electron density and temperature.

Measurement and Analysis of Atomic Hydrogen and Diatomic Molecular AlO, C2, CN, and TiO Spectra Following Laser-induced Optical Breakdown

In this work, we present time-resolved measurements of atomic and diatomic spectra following laser-induced optical breakdown. A typical LIBS arrangement ...

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14.1K Views.  University of Tennessee Space Institute. Time-resolved atomic and diatomic molecular species are measured using LIBS. The spectra are collected at various time delays following the generation of optical breakdown plasma with Nd:YAG laser radiation and are analyzed to infer electron density and temperature.

Video: Measurement and Analysis of Atomic Hydrogen and Diatomic Molecular AlO, C2, CN, and TiO Spectra Following Laser-induced Optical Breakdown

Construction and Testing of Coin Cells of Lithium Ion Batteries

Rechargeable lithium ion batteries have wide applications in electronics, where customers always demand more capacity and longer lifetime. Lithium ion batteries have also been considered to be used in electric and hybrid vehicles1 or even electrical grid stabilization systems2. All these applications simulate a dramatic increase in the research and development of battery materials3-7, including new materials3,8, doping9, nanostructuring10-13, coatings or surface modifications14-17 and novel binders18. Consequently, an increasing number of physicists, chemists and materials scientists have recently ventured into this area. Coin cells are widely used in research laboratories to test new battery materials; even for the research and development that target large-scale and high-power applications, small coin cells are often used to test the capacities and rate capabilities of new materials in the initial stage. 
 In 2010, we started a National Science Foundation (NSF) sponsored research project to investigate the surface adsorption and disordering in battery materials (grant no. DMR-1006515). In the initial stage of this project, we have struggled to learn the techniques of assembling and testing coin cells, which cannot be achieved without numerous help of other researchers in other universities (through frequent calls, email exchanges and two site visits). Thus, we feel that it is beneficial to document, by both text and video, a protocol of assembling and testing a coin cell, which will help other new researchers in this field. This effort represents the "Broader Impact" activities of our NSF project, and it will also help to educate and inspire students.
In this video article, we document a protocol to assemble a CR2032 coin cell with a LiCoO2 working electrode, a Li counter electrode, and (the mostly commonly used) polyvinylidene fluoride (PVDF) binder. To ensure new learners to readily repeat the protocol, we keep the protocol as specific and explicit as we can. However, it is important to note that in specific research and development work, many parameters adopted here can be varied. First, one can make coin cells of different sizes and test the working electrode against a counter electrode other than Li. Second, the amounts of C black and binder added into the working electrodes are often varied to suit the particular purpose of research; for example, large amounts of C black or even inert powder were added to the working electrode to test the "intrinsic" performance of cathode materials14. Third, better binders (other than PVDF) have also developed and used18. Finally, other types of electrolytes (instead of LiPF6) can also be used; in fact, certain high-voltage electrode materials will require the uses of special electrolytes7.

A protocol to construct and test coin cells of lithium ion batteries is described. The specific procedures of making a working electrode, preparing a counter electrode, assembling a cell inside a glovebox and testing the cell are presented.

Rechargeable lithium ion batteries have wide applications in electronics, where customers always demand more capacity and longer lifetime.  Lithium ion ...

Laser-induced Breakdown Spectroscopy: A New Approach for Nanoparticle's Mapping and Quantification in Organ Tissue

Emission spectroscopy of laser-induced plasma was applied to elemental analysis of biological samples. Laser-induced breakdown spectroscopy (LIBS) performed on thin sections of rodent tissues: kidneys and tumor, allows the detection of inorganic elements such as (i) Na, Ca, Cu, Mg, P, and Fe, naturally present in the body and (ii) Si and Gd, detected after the injection of gadolinium-based nanoparticles. The animals were euthanized 1&#160;to 24 hr&#160;after intravenous injection of particles. A two-dimensional scan of the sample, performed using a motorized micrometric 3D-stage, allowed the infrared laser beam exploring the surface with a lateral resolution less than 100 &#956;m. Quantitative chemical images of Gd element inside the organ were obtained with sub-mM sensitivity. LIBS offers a simple and robust method to study the distribution of inorganic materials without any specific labeling. Moreover, the compatibility of the setup with standard optical microscopy emphasizes its potential to provide multiple images of the same biological tissue with different types of response:&#160;elemental, molecular, or cellular.

Laser-induced Breakdown Spectroscopy: A New Approach for Nanoparticle&#039;s Mapping and Quantification in Organ Tissue

Laser-induced breakdown spectroscopy performed on thin organ and tumor tissue successfully detected natural elements and artificially injected gadolinium (Gd), issued from Gd-based nanoparticles. Images of chemical elements reached a resolution of 100 &#956;m and quantitative sub-mM sensitivity. The compatibility of the setup with standard optical microscopy emphasizes its potential to provide multiple images of a same biological tissue.

Emission spectroscopy of laser-induced plasma was applied to elemental analysis of biological samples. Laser-induced breakdown spectroscopy (LIBS) ...

Quantification of Hydrogen Concentrations in Surface and Interface Layers and Bulk Materials through Depth Profiling with Nuclear Reaction Analysis

Nuclear reaction analysis (NRA) via the resonant 1H(15N,&#945;&#947;)12C reaction is a highly effective method of depth profiling that quantitatively and non-destructively reveals the hydrogen density distribution at surfaces, at interfaces, and in the volume of solid materials with high depth resolution. The technique applies a 15N ion beam of 6.385 MeV provided by an electrostatic accelerator and specifically detects the 1H isotope in depths up to about 2 &#956;m from the target surface. Surface H coverages are measured with a sensitivity in the order of ~1013 cm-2 (~1% of a typical atomic monolayer density) and H volume concentrations with a detection limit of ~1018 cm-3 (~100 at. ppm). The near-surface depth resolution is 2-5 nm for surface-normal 15N ion incidence onto the target and can be enhanced to values below 1 nm for very flat targets by adopting a surface-grazing incidence geometry. The method is versatile and readily applied to any high vacuum compatible homogeneous material with a smooth surface (no pores). Electrically conductive targets usually tolerate the ion beam irradiation with negligible degradation. Hydrogen quantitation and correct depth analysis require knowledge of the elementary composition (besides hydrogen) and mass density of the target material. Especially in combination with ultra-high vacuum methods for in-situ target preparation and characterization, 1H(15N,&#945;&#947;)12C NRA is ideally suited for hydrogen analysis at atomically controlled surfaces and nanostructured interfaces. We exemplarily demonstrate here the application of 15N NRA at the MALT Tandem accelerator facility of the University of Tokyo to (1) quantitatively measure the surface coverage and the bulk concentration of hydrogen in the near-surface region of a H2 exposed Pd(110) single crystal, and (2) to determine the depth location and layer density of hydrogen near the interfaces of thin SiO2 films on Si(100).

We illustrate the application of 1H(15N,&#945;&#947;)12C resonant nuclear reaction analysis (NRA) to quantitatively evaluate the density of hydrogen atoms on the surface, in the volume, and at an interfacial layer of solid materials. The near-surface hydrogen depth profiling of a Pd(110) single crystal and of SiO2/Si(100) stacks is described.

Nuclear reaction analysis (NRA) via the resonant 1H(15N,&#945;&#947;)12C reaction is a highly effective method of depth profiling that quantitatively and ...

Laser-induced Forward Transfer of Ag Nanopaste

Over the past decade, there has been much development of non-lithographic methods1-3 for printing metallic inks or other functional materials. Many of these processes such as inkjet3 and laser-induced forward transfer (LIFT)4 have become increasingly popular as interest in printable electronics and maskless patterning has grown. These additive manufacturing processes are inexpensive, environmentally friendly, and well suited for rapid prototyping, when compared to more traditional semiconductor processing techniques. While most direct-write processes are confined to two-dimensional structures and cannot handle materials with high viscosity (particularly inkjet), LIFT can transcend both constraints if performed properly. Congruent transfer of three dimensional pixels (called voxels), also referred to as laser decal transfer (LDT)5-9, has recently been demonstrated with the LIFT technique using highly viscous Ag nanopastes to fabricate freestanding interconnects, complex voxel shapes, and high-aspect-ratio structures. In this paper, we demonstrate a simple yet versatile process for fabricating a variety of micro- and macroscale Ag structures. Structures include simple shapes for patterning electrical contacts, bridging and cantilever structures, high-aspect-ratio structures, and single-shot, large area transfers using a commercial digital micromirror device (DMD) chip.

We demonstrate the use of the Laser-induced forward transfer technique (LIFT) for the printing of high-viscosity Ag paste. This technique offers a simple, low temperature, robust process for non-lithographically printing microscale 2D and 3D structures.

Over the past decade, there has been much development of non-lithographic methods1-3 for printing metallic inks or other functional materials. Many of ...

Optical Trap Loading of Dielectric Microparticles In Air

We demonstrate a method to trap a selected dielectric microparticle in air using radiation pressure from a single-beam gradient optical trap. Randomly scattered dielectric microparticles adhered to a glass substrate are momentarily detached using ultrasonic vibrations generated by a piezoelectric transducer (PZT). Then, the optical beam focused on a selected particle lifts it up to the optical trap while the vibrationally excited microparticles fall back to the substrate. A particle may be trapped at the nominal focus of the trapping beam or at a position above the focus (referred to here as the levitation position) where gravity provides the restoring force. After the measurement, the trapped particle can be placed at a desired position on the substrate in a controlled manner. 
In this protocol, an experimental procedure for selective optical trap loading in air is outlined. First, the experimental setup is briefly introduced. Second, the design and fabrication of a PZT holder and a sample enclosure are illustrated in detail. The optical trap loading of a selected microparticle is then demonstrated with step-by-step instructions including sample preparation, launching into the trap, and use of electrostatic force to excite particle motion in the trap and measure charge. Finally, we present recorded particle trajectories of Brownian and ballistic motions of a trapped microparticle in air. These trajectories can be used to measure stiffness or to verify optical alignment through time domain and frequency domain analysis. Selective trap loading enables optical tweezers to track a particle and its changes over repeated trap loadings in a reversible manner, thereby enabling studies of particle-surface interaction.

A protocol for launching and stably trapping selected dielectric microparticles in air is presented.

We demonstrate a method to trap a selected dielectric microparticle in air using radiation pressure from a single-beam gradient optical trap. Randomly ...

In Situ High Pressure Hydrogen Tribological Testing of Common Polymer Materials Used in the Hydrogen Delivery Infrastructure

High pressure hydrogen gas is known to adversely affect metallic components of compressors, valves, hoses, and actuators. However, relatively little is known about the effects of high pressure hydrogen on the polymer sealing and barrier materials also found within these components. More study is required in order to determine the compatibility of common polymer materials found in the components of the hydrogen fuel delivery infrastructure with high pressure hydrogen. As a result, it is important to consider the changes in physical properties such as friction and wear in situ while the polymer is exposed to high pressure hydrogen. In this protocol, we present a method for testing the friction and wear properties of ethylene propylene diene monomer (EPDM) elastomer samples in a 28 MPa high pressure hydrogen environment using a custom-built in situ pin-on-flat linear reciprocating tribometer. Representative results from this testing are presented which indicate that the coefficient of friction between the EPDM sample coupon and steel counter surface is increased in high pressure hydrogen as compared to the coefficient of friction similarly measured in ambient air.

In Situ High Pressure Hydrogen Tribological Testing of Common Polymer Materials Used in the Hydrogen Delivery Infrastructure

A test methodology for quantifying tribological properties of polymers used in hydrogen infrastructure service is demonstrated and characteristic results for a common elastomer are discussed.

High pressure hydrogen gas is known to adversely affect metallic components of compressors, valves, hoses, and actuators. However, relatively little is ...

Atomic Layer Deposition of Vanadium Dioxide and a Temperature-dependent Optical Model

Vanadium dioxide is a material that has a reversible metal-insulator phase change near 68 &#176;C. To grow VO2 on a wide variety of substrates, with wafer-scale uniformity and angstrom level control of thickness, the method of atomic-layer deposition was chosen. This ALD process enables high-quality, low-temperature (&#8804;150 &#176;C) growth of ultrathin films (100-1000 &#197;) of VO2. For this demonstration, the VO2 films were grown on sapphire substrates. This low temperature growth technique produces mostly amorphous VO2 films. A subsequent anneal in an ultra-high vacuum chamber with a pressure of 7x10-4 Pa of ultra-high purity (99.999%) oxygen produced oriented, polycrystalline VO2 films. The crystallinity, phase, and strain of the VO2 were determined by Raman spectroscopy and X-ray diffraction, while the stoichiometry and impurity levels were determined by X-ray photoelectron spectroscopy, and finally the morphology was determined by atomic force microscopy. These data demonstrate the high-quality of the films grown by this technique. A model was created to fit to the data for VO2 in its metallic and insulating phases in the near infrared spectral region. The permittivity and refractive index of the ALD VO2 agreed well with the other fabrication methods in its insulating phase, but showed a difference in its metallic state. Finally, the analysis of the films&#39; optical properties enabled the creation of a wavelength- and temperature-dependent model of the complex optical refractive index for developing VO2 as a tunable refractive index material.

Thin films (100-1000 &#197;) of vanadium dioxide (VO2) were created by atomic-layer deposition (ALD) on sapphire substrates. Following this, the optical properties were characterized through the metal-insulator transition of VO2. From the measured optical properties, a model was created to describe the tunable refractive index of VO2.

Vanadium dioxide is a material that has a reversible metal-insulator phase change near 68 &#176;C. To grow VO2 on a wide variety of substrates, with ...

Quantitative Analysis of Vacuum Induction Melting by Laser-induced Breakdown Spectroscopy

Vacuum induction melting is a popular method for refining high purity metal and alloys. Traditionally, standard process control in metallurgy involves several steps, include drawing samples, cooling, cutting, transport to the laboratory, and analysis. The whole analysis process requires more than 30 minutes, which hinders on-line process control. Laser-induced breakdown spectroscopy is an excellent on-line analysis method that can satisfy the requirements of vacuum induction melting because it is fast and noncontact and does not require sample preparation. The experimental facility uses a lamp-pumped Q-switched laser to ablate melted liquid steel with an output energy of 80 mJ, a frequency of 5 Hz, a FWHM pulse width of 20 ns, and a working wavelength of 1,064 nm. A multi-channel linear charge coupled device (CCD) spectrometer is used to measure the emission spectrum in real time, with a spectral range from 190 to 600 nm and a resolution of 0.06 nm at a wavelength of 200 nm. The protocol includes several steps: standard alloy sample preparation and an ingredient test, smelting of standard samples and determination of the laser breakdown spectrum, and construction of the elements concentration quantitative analysis curve of each element. To realize the concentration analysis of unknown samples, the spectrum of a sample also needs to be measured and disposed with the same process. The composition of all main elements in the melted alloy can be quantitatively analyzed with an internal standard method. The calibration curve shows that the limit of detection of most metal elements ranges from 20-250 ppm. The concentration of elements, such as Ti, Mo, Nb, V, and Cu, can be lower than 100 ppm, and the concentrations of Cr, Al, Co, Fe, Mn, C, and Si range from 100-200 ppm. The R2 of some calibration curves can exceed 0.94.

During vacuum induction melting, laser-induced breakdown spectroscopy is used to perform real-time quantitative analysis of the main-ingredient elements of a molten alloy.

Vacuum induction melting is a popular method for refining high purity metal and alloys. Traditionally, standard process control in metallurgy involves ...

Method Development for Contactless Resonant Cavity Dielectric Spectroscopic Studies of Cellulosic Paper

The current analytical techniques for characterizing printing and graphic arts substrates are largely ex situ and destructive. This limits the amount of data that can be obtained from an individual sample and renders it difficult to produce statistically relevant data for unique and rare materials. Resonant cavity dielectric spectroscopy is a non-destructive, contactless technique which can simultaneously interrogate both sides of a sheeted material and provide measurements which are suitable for statistical interpretations. This offers analysts the ability to quickly discriminate between sheeted materials based on composition and storage history. In this methodology article, we demonstrate how contactless resonant cavity dielectric spectroscopy may be used to differentiate between paper analytes of varying fiber species compositions, to determine the relative age of the paper, and to detect and quantify the amount of post-consumer waste (PCW) recycled fiber content in manufactured office paper.

A protocol for the non-destructive analysis of the fiber content and relative age of paper.

The current analytical techniques for characterizing printing and graphic arts substrates are largely ex situ and destructive. This limits the amount of ...

Measurement of Chladni Mode Shapes with an Optical Lever Method

Quantitatively determining the Chladni pattern of an elastic plate is of great interest in both physical science and engineering applications. In this paper, a method of measuring mode shapes of a vibrating plate based on an optical lever method is proposed. Three circular acrylic plates were employed in the measurement under different center harmonic excitations. Different from a traditional method, only an ordinary laser pen and a light screen made of ground glass are employed in this novel approach. The approach is as follows: the laser pen projects a beam to the vibrating plate perpendicularly, and then the beam is reflected to the light screen in the distance, on which a line segment made of the reflected spot is formed. Due to the principle of vision persistence, the light spot could be read as a bright straight line. The relationship between the slope of the mode shape, length of the light spot and the distance of the vibrating plate and the light screen can be obtained with algebraic operations. Then the mode shape can be determined by integrating the slope distribution with suitable boundary conditions. The full-field mode shapes of Chladni plate could also be determined further in such a simple way.

A simple method of measuring the Chladni mode shape on an elastic plate by the principle of an optical lever is proposed.

Quantitatively determining the Chladni pattern of an elastic plate is of great interest in both physical science and engineering applications. In this ...