Name: quantitative analysis by thermogravimetry-mass spectrum analysis for reactions with evolved gases
Uploaded: 2018-10-29T14:00:00
Description: Watch this Scientific Journal Video about Quantitative Analysis by Thermogravimetry-Mass Spectrum Analysis for Reactions with Evolved Gases at JoVE.com

The authors gratefully acknowledge the financial support from the National Natural Science Foundation of China (Grant No. 51506199).

1. Calibration of ECSA for the TG-MS System
<ol>
	<li>Calibration of the characteristic spectrum
	<ol>
		<li>Prepare the evolved gases of CO2, H2O, CH4, He, etc. to be calibrated, modulating the gas pressure at 0.15 MPa.</li>
		<li>Connect the gas cylinder to the TG-MS system by stainless steel tube and purge the individual gas into the TG-MS system with a flow rate of 100 mL/min.</li>
		<li>Monitor the mass spectrum of the individual gas. Carefully watch and c...

<ol>
	<li>Li, R. B., Xia, H. D., Wei, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> 15th International Conference on Clean Energy (ICCE-2017). , (2017).</li><li>Zou, C., Ma, C., Zhao, J., Shi, R., Li, X. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Characterization+and+non-isothermal+kinetics+of+Shenmu+bituminous+coal+devolatilization+by+TG-MS.">Characterization and non-isothermal kinetics of Shenmu bituminous coal devolatilization by TG-MS.</a> Journal of Analytical and Applied Pyrolysis. 127, 309-320 (2017).</li><li>Jayaraman, K., Kok, M. V., Gokalp, I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Thermogravimetric+and+mass+spectrometric+(TG-MS)+analysis+and+kinetics+of+coal-biomass+blends.">Thermogravimetric and mass spectrometric (TG-MS) analysis and kinetics of coal-biomass blends.</a> Renewable Energy. 101, 293-300 (2017).</li><li>Tsugoshi, T., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Evolved+gas+analysis-mass+spectrometry+using+skimmer+interface+and+ion+attachment+mass+spectrometry.">Evolved gas analysis-mass spectrometry using skimmer interface and ion attachment mass spectrometry.</a> Journal of Thermal Analysis and Calorimetry. 80 (3), 787-789 (2005).</li><li>JaenickeRossler, K., Leitner, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=TA-MS+for+high+temperature+materials.">TA-MS for high temperature materials.</a> Thermochimica Acta. (1-2), 133-145 (1997).</li><li>Fendt, A., Geissler, R., Streibel, T., Sklorz, M., Zimmermann, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hyphenation+of+two+simultaneously+employed+soft+photo+ionization+mass+spectrometers+with+thermal+analysis+of+biomass+and+biochar.">Hyphenation of two simultaneously employed soft photo ionization mass spectrometers with thermal analysis of biomass and biochar.</a> Thermochimica Acta. , 155-163 (2013).</li><li>Maciejewski, M., Baiker, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Quantitative+calibration+of+mass+spectrometric+signals+measured+in+coupled+TA-MS+system.">Quantitative calibration of mass spectrometric signals measured in coupled TA-MS system.</a> Thermochimica Acta. 295 (1-2), 95-105 (1997).</li><li>Maciejewski, M., Muller, C. A., Tschan, R., Emmerich, W. D., Baiker, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Novel+pulse+thermal+analysis+method+and+its+potential+for+investigating+gas-solid+reactions.">Novel pulse thermal analysis method and its potential for investigating gas-solid reactions.</a> Thermochimica Acta. 295 (1-2), 167-182 (1997).</li><li>Xia, H. D., Wei, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Equivalent+characteristic+spectrum+analysis+in+TG-MS+system.">Equivalent characteristic spectrum analysis in TG-MS system.</a> Thermochimica Acta. 602, 15-21 (2015).</li><li>Li, R. B., Chen, Q., Xia, H. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Study+on+pyrolysis+characteristics+of+pretreated+high-sodium+(Na)+Zhundong+coal+by+skimmer-type+interfaced+TG-DTA-EI/PI-MS+system.">Study on pyrolysis characteristics of pretreated high-sodium (Na) Zhundong coal by skimmer-type interfaced TG-DTA-EI/PI-MS system.</a> Fuel Processing Technology. 170, 79-87 (2018).</li><li>Li, C. Z. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Some+recent+advances+in+the+understanding+of+the+pyrolysis+and+gasification+behaviour+of+Victorian+brown+coal.">Some recent advances in the understanding of the pyrolysis and gasification behaviour of Victorian brown coal.</a> Fuel. 86 (12-13), 1664-1683 (2007).</li><li>Song, H. J., Liu, G. R., Zhang, J. Z., Wu, J. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pyrolysis+characteristics+and+kinetics+of+low+rank+coals+by+TG-FTIR+method.">Pyrolysis characteristics and kinetics of low rank coals by TG-FTIR method.</a> Fuel Processing Technology. 156, 454-460 (2017).</li><li>Kashimura, N., Hayashi, J., Li, C. Z., Sathe, C., Chiba, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Evidence+of+poly-condensed+aromatic+rings+in+a+Victorian+brown+coal.">Evidence of poly-condensed aromatic rings in a Victorian brown coal.</a> Fuel. 83 (1), 97-107 (2004).</li><li>Li, C. Z., Sathe, C., Kershaw, J. R., Pang, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fates+and+roles+of+alkali+and+alkaline+earth+metals+during+the+pyrolysis+of+a+Victorian+brown+coal.">Fates and roles of alkali and alkaline earth metals during the pyrolysis of a Victorian brown coal.</a> Fuel. 79 (3-4), 427-438 (2000).</li></ol>

This protocol could be easily modified to accommodate other measurements for studying evolved gases and pyrolysis reactions by a TG-MS system. As we know, the evolved volatile from the pyrolysis of biomass, coal, or other solid/liquid fuel does not always include only the inorganic gases (e.g., CO, H2, and CO2) but also the organic ones (e.g., C2H4, C6H5OH, and C7H8). Moreover, massive fragments would result from the...

Understanding in depth the real features of a reaction process is one critical issue for the development of advanced materials and the establishment of a new energy conversion system or metallurgy production process1. Almost all reactions are carried out under unsteady conditions, and because their parameters, including the concentration and flow rate of reactants and products, always change with the temperature or pressure, it is difficult to clearly characterize the reaction feature by only one parameter, for instance through the Arrhenius Equation. In fact, the concentration implies only the relationship between the component and the mixture. Real reaction behavior might not be affected, even though the concentration of a component in one complicated reaction is adjusted to a great extent since the other components might have a stronger influence on it. On the contrary, the flow rate of each component, as an absolute quantity, can give persuasive information to understand the characteristics of the reactions, especially very complicated ones.
At present, the TG-MS coupling system equipped with the electron ionization (EI) technique has been used as a prevalent tool for analyzing the features of reactions with evolved gases2,3,4. However, first, it should be noted that the ion current (IC) obtained from an MS system makes it difficult to directly reflect the flow rate or concentration of the evolved gas. The massive IC overlap, fragment, severe mass discrimination, and diffusion effect of gases in the furnace of a thermogravimeter can greatly hamper the quantitative analysis for TG-MS5. Second, EI is the most common and readily available strong ionization technique. An MS system equipped with EI easily results in fragments and does not often directly reflect some organic gases with a larger molecular weight. Therefore, MS systems with different soft ionization techniques (e.g., photoionization [PI]) are required simultaneously to be hyphenated to a thermobalance and applied to evolved gas analysis6. Third, the intensity of the IC at some mass-to-charge ratios (m/z) cannot be used to determine the dynamic characteristic of any reaction gas, because it is often affected by the other ICs for a complex reaction with multicomponent evolved gases. For example, the drop in the IC curve of a specific gas does not necessarily indicate a decrease in its flow rate or concentration; instead, maybe it is affected by the other gases in the complex system. Thus, it is important to take into account all gases&#39; ICs, certainly with a carrier gas and inert gas.
In fact, quantitative analysis based on mass spectrum greatly depends on the determination of the calibration factor and relative sensitivity of the TG-MS system. Maciejewski and Baiker7 investigated in a thermal analyzer-mass spectrometer (TA-MS) system, in which the TA is connected by a heated capillary to a quadrupole MS, the effect of experimental parameters, including the concentration of gases species, temperature, flow rate, and properties of the carrier gas, on the sensitivity of the mass spectrometric analysis. The evolved gases were calibrated by the decomposition of the solids via a well-known, stoichiometric reaction and injecting a certain amount of gas into the carrier gas stream with a constant rate. The experimental results show that there is a negative linear correlation of the MS signal intensity of evolved gas to that of the carrier gas flow rate, and the evolved gas MS intensity is not influenced by the temperature and the amount of analyzed gas. Further, based on the calibration method, Maciejewski et al.8 invented the pulse thermal analysis (PTA) method, which provides an opportunity to determine the flow rate by simultaneously monitoring the changes of the mass, enthalpy, and gas composition resulted from the reaction course. However, it is still hard to give persuasive information about the complicated reaction (e.g., coal combustion/gasification) by using the traditional TG-MS analysis or PTA methods.
In order to overcome the difficulties and disadvantages of the traditional measuring and analysis method for the TG-MS system, we developed the quantitative analysis method of ECSA9. The fundamental principle of ECSA is based on the TG-MS coupling mechanism. The ECSA can take into account all gases&#39; ICs, including the reaction gases&#39;, carrier gases&#39;, and inert gases&#39;. After building the calibration factor and relative sensitivity of some gas, the real mass or molar flow rate of each component can be determined by the calculation of the IC matrix (i.e., the mass spectrum of TG-MS). Compared with the other methods, ECSA for the TG-MS system can effectively separate the overlapping spectrum and eliminate the mass discrimination and the temperature-dependent effect of TG. The data produced by ECSA have proved to be reliable via a comparison between the mass flow rate of evolved gas and mass loss data by differential thermogravimetry (DTG). In this study, we used an advanced TG-DTA-EI/PI-MS instrument10 to carry out the experiments (Figure 1). This instrument consists of a cylindrical quadrupole MS and a horizontal thermogravimetry-differential thermal analyzer (TG-DTA) equipped with both EI and PI mode, and with a skimmer interface. ECSA for the TG-MS system determines the physics parameters of all evolved gases by utilizing the actual TG-MS coupling mechanism (i.e., an equal relative pressure) to implement the quantitative analysis. The overall analysis process includes a calibration, the test itself, and data analysis (Figure 2). We present two example experiments: (1) the decomposition of CaCO3 with only evolved gas of CO2 and the decomposition of hydromagnesite with evolved gas of CO2 and H2O, to evaluate the ECSA on a single-component system measurement and (2) the thermal pyrolysis of brown coal with evolved gases of inorganic gases CO, H2, and CO2, and organic gases CH4, C2H4, C2H6, C3H8, C6H14, etc., to evaluate the ECSA on a multi-component system measurement. ECSA based on the TG-MS system is a comprehensive solution method for quantitatively determining the amount of evolved gas in thermal reactions.

<table>
	<tbody>
		<tr>
			<td>CaCO3 and Ca(OH)2</td>
			<td>Sinopharm Chemical Reagent</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>hydromagnesite</td>
			<td>Bangko Coarea in Tibet</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Zhundong coal</td>
			<td>the coal field in the Mori Kazak Autonomous County, Junggar basin, Xinjiang province of China</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>ThermoMass Photo/H</td>
			<td>Rigaku Corporation</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>The STA449F3 synchronous thermal analyzer and QMS403C quadrupole MS analyzer</td>
			<td>NETZSCH</td>
			<td></td>
			<td></td>
		</tr>
	</tbody>
</table>

quantitative analysis by thermogravimetry-mass spectrum analysis for reactions with evolved gases

During energy conversion, material production, and metallurgy processes, reactions often have the features of unsteadiness, multistep, and multi-intermediates. Thermogravimetry-mass spectrum (TG-MS) is seen as a powerful tool to study reaction features. However, reaction details and reaction mechanics have not been effectively obtained directly from the ion current of TG-MS. Here, we provide a method of an equivalent characteristic spectrum analysis (ECSA) for analyzing the mass spectrum and giving the mass flow rate of reaction gases as precise as possible. The ECSA can effectively separate overlapping ion peaks and then eliminate the mass discrimination and temperature-dependent effect. Two example experiments are presented: (1) the decomposition of CaCO3 with evolved gas of CO2 and the decomposition of hydromagnesite with evolved gas of CO2 and H2O, to evaluate the ECSA on single-component system measurement and (2) the thermal pyrolysis of Zhundong coal with evolved gases of inorganic gases CO, H2, and CO2, and organic gases C2H4, C2H6, C3H8, C6H14, etc., to evaluate the ECSA on multi-component system measurement. Based on the successful calibration of the characteristic spectrum and relative sensitivity of specific gas and the ECSA on mass spectrum, we demonstrate that the ECSA accurately gives the mass flow rates of each evolved gas, including organic or inorganic gases, for not only single but multi-component reactions, which cannot be implemented by the traditional measurements.

The thermal decomposition of CaCO3 is a relatively simple reaction, which was used to demonstrate the applicability of the ECSA method. After calibrating the characteristic peak and relative sensitivity of CO2 to carrier gas He, the actual mass flow rate of CO2 evolved by the thermal decomposition of CaCO3 was calculated by the ECSA method and was compared with the actual mass loss (Figure 3). It is shown that there...

Watch this Scientific Journal Video about Quantitative Analysis by Thermogravimetry-Mass Spectrum Analysis for Reactions with Evolved Gases at JoVE.com

Quantitative Analysis by Thermogravimetry-Mass Spectrum Analysis for Reactions with Evolved Gases

Precise determination of the evolved gases&#39; flow rate is key to study the details of reactions. We provide a novel quantitative analysis method of equivalent characteristic spectrum analysis for thermogravimetry-mass spectrum analysis by establishing the calibration system of the characteristic spectrum and relative sensitivity, for obtaining the flow rate.

During energy conversion, material production, and metallurgy processes, reactions often have the features of unsteadiness, multistep, and ...

This method can help answer key questions in the energy, chemistry, and the metallurgy field about how to identify reaction kinetic parameters and evolved gas compositions. To me, an advantage of this technique is that the mass fluid of individual gases evolved from reactions can be qualitatively and quantitatively precisely determined. Through this method, can provide insight into reactions in the energy, chemistry, metallurgy system, and so on.It can also be applied to other systems such as food, pharmacy, or materials. To calibrate a characteristic spectrum, prepare the evolved gases to be calibrated, modulating the gas pressure at 0.15 megapascals. Use a stainless steel tube to connect each gas cylinder to the thermogravimetry mass spectrum, or TG-MS system, and purge all the evolved gases into the TG-MS system at a 100 milliliters per minute flow rate.Monitor the mass spectrum of each individual gas, carefully watching and comparing the characteristic peaks of the gases to be calibrated and any possible impurities within the gases. To calibrate the relative sensitivity of the gases, purge the reference gas at 300 milliliters per minute flow rate into the TG-MS system for 20 minutes to clean the system. Next, synchronously purge each of the calibrated gases with the reference gas into the TG-MS system at a 100 milliliter per minute flow rate.Then calculate the relative sensitivity of each gas according to the known flow rate and the mass spectrum as indicated in the equation. To prepare the samples, collect 10 grams of calcium carbonate with an average diameter of 15 micrometers, 10 grams of a white block of hydromagnesite or 20 grams of Zhundong coal. Break the hydromagnesite block into less than three millimeter pieces and grind the pieces with a machine stirred mill to approximately 10 micrometers.Then dry all of the samples for 24 hours in a 105 degree Celsius oven, breaking and grinding the coal in a mill the next day to obtain a particle size range of 180 to 355 micrometers. To test the thermal reactions of the samples, purge the TG-MS system with helium as the carrier gas for two hours to expel the air and moisture and heat the instrument to around 500 degree Celsius. When the system is cooled back to room temperature, use mass spectrometry to monitor the atmosphere for 20 minutes, carefully watching and comparing the characteristic carbon dioxide and helium peaks and the impurity peaks of the oxygen, nitrogen, and water gases.Weigh 10 milligrams of the sample of interest on a precision electronic balance, and add the weighed sample to an aluminum oxide crucible. Place the crucible with the sample into the TG system and close the furnace. Then set the appropriate operating parameters for the sample being tested.So a reference gas in the calibration must be the same as that in the sample testing process and must never react with the evolved gases. We recommend using helium as the carrier gas in both the calibration and the test. For qualitative and quantitative analysis of the sample data, load the 3D mass spectrum data onto the computer connected to the TG-MS system and use the equivalent characteristic spectrum analysis, ECSA, method to calculate the actual sample parameters based on the previously determined calibrated characteristic peak and the relative sensitivity of the sample.The thermal reaction can then be analyzed according to the actual sample parameters. After calibrating the characteristic peak and relative sensitivity of carbon dioxide to the carrier gas, helium, the actual mass flow rate of carbon dioxide evolved by thermal decomposition of calcium carbonate can be calculated by the ECSA method and compared with the actual mass loss. In this representative analysis, there was a good agreement between the mass flow rate of carbon dioxide and the mass loss data by digital thermogravimetry over the entire measurement process.Comparison of the thermal decomposition process of hydromagnesite by ECSA and the calibration of carbon dioxide and water revealed that these data were also in good agreement with the experimental digital thermogravimetry data. Combining both the electron ionization and photoionization measuring modes, this representative pyrolysis of Zhundong coal revealed the presence of 16 different volatile gases. After detailed determination of the mass spectrum and sensitivity of each identified gas to the carrier gas, the mass flow rate of each gas was calculated and used to compare the mass ion data for each gas based on the same operating parameters.While attempting this procedure, it's important to remember to build the composition fixture and the relative sensitivity of the gases before testing. Following this procedure, a method like differential thermal analysis combined ECSA can be performed to answer additional questions about the features of the reactions without evolved gases. After its development, this technique paved the way for the researchers in the field of energy, chemistry, metallurgy, and so on, to explore using gas reactions and mechanisms in energy conversion and advanced materials development.

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Engineering

Analysis of Contact Interfaces for Single GaN Nanowire Devices

Single GaN nanowire (NW) devices fabricated on SiO2 can exhibit a strong degradation after annealing due to the occurrence of void formation at the contact/SiO2 interface. This void formation can cause cracking and delamination of the metal film, which can increase the resistance or lead to a complete failure of the NW device. In order to address issues associated with void formation, a technique was developed that removes Ni/Au contact metal films from the substrates to allow for the examination and characterization of the contact/substrate and contact/NW interfaces of single GaN NW devices. This procedure determines the degree of adhesion of the contact films to the substrate and NWs and allows for the characterization of the morphology and composition of the contact interface with the substrate and nanowires. This technique is also useful for assessing the amount of residual contamination that remains from the NW suspension and from photolithographic processes on the NW-SiO2 surface prior to metal deposition. The detailed steps of this procedure are presented for the removal of annealed Ni/Au contacts to Mg-doped GaN NWs on a SiO2 substrate.

A technique was developed that removes Ni/Au contact metal films from their substrate to allow for the examination and characterization of the contact/substrate and contact/NW interfaces of single GaN nanowire devices.

Single GaN nanowire (NW) devices fabricated on SiO2 can exhibit  a strong degradation after annealing due to the  occurrence of void formation at the ...

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 ...

Using Synchrotron Radiation Microtomography to Investigate Multi-scale Three-dimensional Microelectronic Packages

Synchrotron radiation micro-tomography (SR&#181;T) is a non-destructive three-dimensional (3D) imaging technique that offers high flux for fast data acquisition times with high spatial resolution. In the electronics industry there is serious interest in performing failure analysis on 3D microelectronic packages, many which contain multiple levels of high-density interconnections. Often in tomography there is a trade-off between image resolution and the volume of a sample that can be imaged. This inverse relationship limits the usefulness of conventional computed tomography (CT) systems since a microelectronic package is often large in cross sectional area 100-3,600 mm2, but has important features on the micron scale. The micro-tomography beamline at the Advanced Light Source (ALS), in Berkeley, CA USA, has a setup which is adaptable and can be tailored to a sample&#39;s properties, i.e., density, thickness, etc., with a maximum allowable cross-section of 36 x 36 mm. This setup also has the option of being either monochromatic in the energy range ~7-43 keV or operating with maximum flux in white light mode using a polychromatic beam. Presented here are details of the experimental steps taken to image an entire 16 x 16 mm system within a package, in order to obtain 3D images of the system with a spatial resolution of 8.7 &#181;m all within a scan time of less than 3 min. Also shown are results from packages scanned in different orientations and a sectioned package for higher resolution imaging. In contrast a conventional CT system would take hours to record data with potentially poorer resolution. Indeed, the ratio of field-of-view to throughput time is much higher when using the synchrotron radiation tomography setup. The description below of the experimental setup can be implemented and adapted for use with many other multi-materials.

For this study synchrotron radiation micro-tomography, a non-destructive three-dimensional imaging technique, is employed to investigate an entire microelectronic package with a cross-sectional area of 16 x 16 mm. Due to the synchrotron&#39;s high flux and brightness the sample was imaged in just 3 min&#160;with an 8.7 &#181;m spatial resolution.

Synchrotron radiation micro-tomography (SR&#181;T) is a non-destructive three-dimensional (3D) imaging technique that offers high flux for fast data ...

Quantitative Hardness Measurement by Instrumented AFM-indentation

In this work, a combination of amplitude-modulated non-contact atomic force microscopy and atomic force spectroscopy is applied for instrumented hardness measurements on an Au(111) surface with atomistic resolution of single plasticity events. A careful experimental procedure is described that includes the force sensor selection, its calibration, the calibration of the cantilever deflection detection system, and the minimization of instrumental drift for accurate and reproducible force-distance measurements. Also, a method for the data analysis is presented that allows the extraction of force-penetration curves from recorded force-distance curves. A typical curve displays a clear elastic deformation regime up to the first plasticity event, or pop-in, with a length in the range of one to two Burger's vectors. Later plasticity events exhibit the same magnitude. The work of plasticity is further extracted from the measurements. Finally, the hardness is determined in combination with the indentation curve using non-contact atomic force microscopy images of the remaining indents.

This experimental protocol describes how atomic force microscopy can be used to measure hardness at the true nanometer scale and to detect single atomistic plasticity events.

In this work, a combination of amplitude-modulated non-contact atomic force microscopy and atomic force spectroscopy is applied for instrumented hardness ...

Measurements of Soil Carbon by Neutron-Gamma Analysis in Static and Scanning Modes

The herein described application of the inelastic neutron scattering (INS) method for soil carbon analysis is based on the registration and analysis of gamma rays created when neutrons interact with soil elements. The main parts of the INS system are a pulsed neutron generator, NaI(Tl) gamma detectors, split electronics to separate gamma spectra due to INS and thermo-neutron capture (TNC) processes, and software for gamma spectra acquisition and data processing. This method has several advantages over other methods in that it is a non-destructive in situ method that measures the average carbon content in large soil volumes, is negligibly impacted by local sharp changes in soil carbon, and can be used in stationary or scanning modes. The result of the INS method is the carbon content from a site with a footprint of ~2.5 - 3 m2 in the stationary regime, or the average carbon content of the traversed area in the scanning regime. The measurement range of the current INS system is &#62;1.5 carbon weight % (standard deviation &#177; 0.3 w%) in the upper 10 cm soil layer for a 1 hmeasurement.

Here, we present the protocol for in situ measurement of soil carbon using the neutron-gamma technique for single point measurements (static mode) or field averages (scanning mode). We also describe system construction and elaborate data treatment procedures.

The herein described application of the inelastic neutron scattering (INS) method for soil carbon analysis is based on the registration and analysis of ...

Effective Analysis of Human Exposure Conditions with Body-worn Dosimeters in the 2.4 GHz Band

A well-defined experimental procedure is put forward to evaluate maximum exposure conditions in a worst-case scenario whilst avoiding the uncertainties caused by the use of personal exposimeters (PEMs) as measuring devices: the body shadow effect (BSE), the limited sensitivity range, and the non-identification of the radiation source. An upper bound for exposure levels to EMF in several indoor enclosures has been measured and simulated. The frequency used for the study is 2.4 GHz, as it is the most commonly used band in indoor communications. Although recorded values are well below the International Commission for Non-Ionizing Radiation Protection (ICNIRP) reference levels, there is a particular need to provide reliable exposure levels within particularly sensitive environments. In terms of electromagnetic field (EMF) exposure, limits established in national and international standards for health protection have been set for unperturbed exposure conditions; that is, for real and objective exposure data that have not been altered in any way.

This study describes a protocol to measure exposure levels in the 2.4 GHz band, avoiding the uncertainties caused by the use of personal exposimeters as measuring devices. These alterations of the exposure levels should be taken into account, especially in compliance testing, where exposure limits are defined from non-perturbed data.

A well-defined experimental procedure is put forward to evaluate maximum exposure conditions in a worst-case scenario whilst avoiding the uncertainties ...

An Analog Macroscopic Technique for Studying Molecular Hydrodynamic Processes in Dense Gases and Liquids

An analog, macroscopic method for studying molecular-scale hydrodynamic processes in dense gases and liquids is described. The technique applies a standard fluid dynamic diagnostic, particle image velocimetry (PIV), to measure: i) velocities of individual particles (grains), extant on short, grain-collision time-scales, ii) velocities of systems of particles, on both short collision-time- and long, continuum-flow-time-scales, iii) collective hydrodynamic modes known to exist in dense molecular fluids, and iv) short- and long-time-scale velocity autocorrelation functions, central to understanding particle-scale dynamics in strongly interacting, dense fluid systems. The basic system is composed of an imaging system, light source, vibrational sensors, vibrational system with a known media, and PIV and analysis software. Required experimental measurements and an outline of the theoretical tools needed when using the analog technique to study molecular-scale hydrodynamic processes are highlighted. The proposed technique provides a relatively straightforward alternative to photonic and neutron beam scattering methods traditionally used in molecular hydrodynamic studies.

An experimentally accessible analog method for studying molecular hydrodynamic processes in dense fluids is presented. The technique uses particle image velocimetry of vibrated, high-restitution grain piles and allows direct, macroscopic observation of dynamical processes known and predicted to exist in strongly interacting, high density gases and liquids.

An analog, macroscopic method for studying molecular-scale hydrodynamic processes in dense gases and liquids is described. The technique applies a ...

Enhanced Electron Injection and Exciton Confinement for Pure Blue Quantum-Dot Light-Emitting Diodes by Introducing Partially Oxidized Aluminum Cathode

Stable and efficient red (R), green (G), and blue (B) light sources based on solution-processed quantum dots (QDs) play important roles in next-generation displays and solid-state lighting technologies. The brightness and efficiency of blue QDs-based light-emitting diodes (LEDs) remain inferior to their red and green counterparts, due to the inherently unfavorable energy levels of different colors of light. To solve these problems, a device structure should be designed to balance the injection holes and electrons into the emissive QD layer. Herein, through a simple autoxidation strategy, pure blue QD-LEDs which are highly bright and efficient are demonstrated, with a structure of ITO/PEDOT:PSS/Poly-TPD/QDs/Al:Al2O3. The autoxidized Al:Al2O3 cathode can effectively balance the injected charges and enhance radiative recombination without introducing an additional electron transport layer (ETL). As a result, high color-saturated blue QD-LEDs are achieved with a maximum luminance over 13,000 cd m-2, and a maximum current efficiency of 1.15 cd A-1. The easily controlled autoxidation procedure paves the way for achieving high-performance blue QD-LEDs.

A protocol is presented for fabricating high-performance, pure blue ZnCdS/ZnS-based quantum dots light-emitting diodes by employing an autoxidized aluminum cathode.

Stable and efficient red (R), green (G), and blue (B) light sources based on solution-processed quantum dots (QDs) play important roles in next-generation ...

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 ...

Infrared Degenerate Four-wave Mixing with Upconversion Detection for Quantitative Gas Sensing

We present a protocol for performing gas spectroscopy using infrared degenerated four-wave mixing (IR-DFWM), for the quantitative detection of gas species in the ppm-to-single-percent range. The main purpose of the method is the spatially resolved detection of low-concentration species, which have no transitions in the visible or near-IR spectral range that could be used for detection. IR-DFWM is a nonintrusive method, which is a great advantage in combustion research, as inserting a probe into a flame can change it drastically. The IR-DFWM is combined with upconversion detection. This detection scheme uses sum-frequency generation to move the IR-DFWM signal from the mid-IR to the near-IR region, to take advantage of the superior noise characteristics of silicon-based detectors. This process also rejects most of the thermal background radiation. The focus of the protocol presented here is on the proper alignment of the IR-DFWM optics and on how to align an intracavity upconversion detection system.

Here, we present a protocol to perform sensitive, spatially resolved gas spectroscopy in the mid-infrared region, using degenerate four-wave mixing combined with upconversion detection.

We present a protocol for performing gas spectroscopy using infrared degenerated four-wave mixing (IR-DFWM), for the quantitative detection of gas species ...