Rene Rodriguez - Academia.edu (original) (raw)

Papers by Rene Rodriguez

OSTI OAI (U.S. Department of Energy Office of Scientific and Technical Information), May 21, 2013

OSTI OAI (U.S. Department of Energy Office of Scientific and Technical Information), Jun 21, 2016

Designs, Codes and Cryptography

Cryptography and Communications, 2021

When synthesizing CuInS2 nanoparticles, species related to the starting materials may physisorb o... more When synthesizing CuInS2 nanoparticles, species related to the starting materials may physisorb or chemisorb onto the product. One nanoparticle characteristic that was confirmed with CHNS combustion analysis showed that as the size of the nanoparticle decreases, more starting material-related species are likely to be attached to nanocrystalline structures of the nanoparticle. Some of these starting material species are useful and necessary through their action as passivating groups. The passivating groups can be solvents or thiol additives used to help make the CuInS2 nanoparticles. Other physisorbed groups are related to solvent or Cu or In salts present as reactants. Although the passivating groups of the nanoparticles are necessary, they likely also lead to a decrease in the usefulness of these particles as semiconductor materials in electronic circuits like solar cells. Too much passivation per CuInS2 formula unit likely corresponds to a decrease in cell device efficiency. Attem...

Dye-sensitized solar cells have recently gained much attention as an alternative to standard n-p ... more Dye-sensitized solar cells have recently gained much attention as an alternative to standard n-p semiconductor photovoltaic materials. Efficiencies for small area cells have been reported to be greater than 10%. Much research has focused on finding new, less expensive, more robust dyes for use in the DSSC cells. Several researchers have studied the use of dyes found in nature such as extracts of blueberries, black rice, and others, as the absorber in the DSSCs. Solar cells employing these dyes have less than 25% of the efficiency of the Ru-based dyes used in commercial cells. H. salinarium utilizes bacteriorhodpsin (bR) as a light-activated proton pump. Due to the efficiency of the process and its absorbance of multiple wavelengths of visible light, we explored its ability to be used as a sensitizer in a dye sensitized solar cell (DSSC). Bacteriorhodopsin would be an ideal dye for DSSC. It is environmentally friendly, biodegradable and inexpensive dye for this process. The results o...

Plasma Chemistry and Plasma Processing, 2004

2008 IEEE Nuclear Science Symposium Conference Record, 2008

Thin films of zinc oxide (ZnO) and titanium oxides (TiO) were deposited on Si (100) substrate by ... more Thin films of zinc oxide (ZnO) and titanium oxides (TiO) were deposited on Si (100) substrate by third generation nanocluster source. Post deposition Oxygen Annealing (OA) effects were evaluated by X-Ray diffraction (XRD), Raman spectroscopy, and photoluminescence (PL). As deposited, diameter of ZnO nanoclusters ˜24 nm and ZnO OA nanoclusters ˜30 nm. As deposited TiO clusters ˜10 nm in diameter, and TiO OA cluster ˜20 nm. XRD shows increased crystal quality and improved ZnO c-axis crystal growth. XRD shows improved stoichiometric TiO2 clusters and preferred anatase phase. Intensity of ZnO PL spectrum has temperature dependence from 10K to 300K. ZnO OA produces red-shifted PL peak, and there are no below-bandgap PL peaks. TiO has room temperature PL with UV peak ˜388 nm and visible peak ˜426 nm. ZnO OA nanoclusters show narrower, red shifted peak by ˜0.07eV compared to as deposited ZnO nanoclusters. This indicates increased average grain size and improved size homogeneity after annea...

Journal of Electronic Materials, 2011

We studied, by current deep-level transient spectroscopy (I-DLTS), point defects in CdZnTe detect... more We studied, by current deep-level transient spectroscopy (I-DLTS), point defects in CdZnTe detectors grown by different techniques. We identified 12 different traps with energy levels from 7 meV to 1.1 eV. Although the levels of most of the identified defects were independent of the crystal growth techniques, nevertheless there were some associated differences in the traps’ energies and densities.

Applied Spectroscopy, 2001

During pulsed plasma enhanced chemical vapor deposition, (PECVD), of silicon nitride thin films, ... more During pulsed plasma enhanced chemical vapor deposition, (PECVD), of silicon nitride thin films, depletion of silane reactant was measured by coherent anti-Stokes Raman scattering, (CARS), spectroscopy as a function of radio frequency pulse width, peak power, and delay time after the rf pulse. The results were correlated with “goodness of deposition parameters” including film thickness, deposition rate, and N-H and Si-H film content. The pulse width and peak power affected the plasma similarly, as silane depletion, film thickness, and rate of film growth all increased with both pulse width and peak power for a 10 Hz repetition rate. The CARS measured silane depletion also increased proportionally with pulse width for short rf pulses but not for long ones. Although the film properties changed with both power and pulse width, there were differences in the effects. A decreasing SiH/NH ratio resulted from increasing peak power, but increases in pulse width lead to an increasing ratio in...

Catalysts

Waste streams from the incineration of metal-containing materials like such as computer processor... more Waste streams from the incineration of metal-containing materials like such as computer processor boards and batteries may contain critical rare earth elements like praseodymium. Data on the solubility of Pr compounds and on their distribution coefficients in supercritical CO2/ionic liquid two-phase systems are important to determine if an ionic liquid/supercritical CO2 two-phase approach is feasible toward the recovery of a particular metal. This work provides data on the solubility of various praseodymium compounds in butyl-methyl-pyrrolidinium bis(trifluoromethylsulfonyl)imide (BMPyTf2N) ionic liquid and on the distribution coefficients of these praseodymium compounds in the supercritical CO2 phase of the two-phase BMPyTf2N ionic liquid/supercritical CO2 system, with and without a tributyl phosphate additive.

Journal of Molecular Liquids

Abstract A wide range of extractant and Task Specific Ionic liquids have been studied for the rem... more Abstract A wide range of extractant and Task Specific Ionic liquids have been studied for the removal of lanthanides and actinides from high level liquid waste (e.g. PUREX and TRUEX etc.). The studies showed that extractant/TSILs can extract lanthanides and actinides simultaneously or it can specifically target the extraction of each group separately from spent nuclear fuel. Researchers noted that lanthanides have similar oxidation states, chemical and physical properties making it difficult to separate individual lanthanides from mixtures of other lanthanides. As a result, only highly efficient and selective extractants can be used for electronic waste. Because of their unique luminescent, magnetic, electrochemical and metallurgic properties, lanthanides are highly sought after materials for numerous technological applications despite their high cost, thus making their recovery from spent nuclear fuel and electronic wastes cost effective. In this review, we compile and describe the different methods for the removal of lanthanides and actinides. The literature review will help us better understand the design, application and performance of the vast group of extractants/ionic liquids already studied. Moreover, the information analyzed in this review will be applied in the synthesis and application of TSILs in further investigations. In addition, it also explained the physical properties of the ILs and its effects on the extraction efficiency of system.

CuIn0.75Ga0.25S2 (CIGS) thin film solar cells have been successfully fabricated using CIGS Wurtzi... more CuIn0.75Ga0.25S2 (CIGS) thin film solar cells have been successfully fabricated using CIGS Wurtzite phase nanoparticles for the first time. The structure of the cell is Glass/Mo/CIGS/CdS/ZnO/ZnO:Al/Ag. The light absorption layer is made from CIGS Wurtzite phase nanoparticles that are formed from single-source precursors through a microwave irradiation. The Wurtzite phase nanoparticles were converted to Chalcopyrite phase film through a single-step annealing process in the presence of argon and sulfur at 450°C. The solar cell made from Wurtzite phase nanoparticles showed 1.6% efficiency and 0.42 fill factor.

Journal of Spectral Imaging

Infrared thermal imaging is an evolving approach useful in non-destructive evaluation of material... more Infrared thermal imaging is an evolving approach useful in non-destructive evaluation of materials for industrial and research purposes. This study investigates the use of this method in combination with multivariate data analysis as an alternative to chemical etching; a destructive method currently used to recover defaced serial numbers stamped in metal. This process involves several unique aspects, each of which works to overcome some pertinent challenges associated with the recovery of defaced serial numbers. Infrared thermal imaging of metal surfaces provides thermal images sensitive to local differences in thermal conductivity of regions of plastic strain existing below a stamped number. These strains are created from stamping pressures distorting the atomic crystalline structure of the metal and extend to depths beneath the stamped number. These thermal differences are quite small and thus not readily visible from the raw thermal images of an irregular surface created by remov...

Materials Sciences and Applications, 2017

The Journal of Physical Chemistry a, Feb 1, 2007

A pulsed, two-beam, thermal lensing experiment was performed to determine the concentration of aq... more A pulsed, two-beam, thermal lensing experiment was performed to determine the concentration of aqueous solutes above the critical point of water. Despite a very significant mirage effect due to thermal gradients in the cell and absorption by water itself, the thermal lensing signal strength for aqueous benzoic acid in supercritical water was found to be linear with concentration in the sub-millimolar range. Although thermal lensing experiments in aqueous media are notoriously insensitive, the sharp density gradient near the critical point considerably improves the signal intensity. In this study a short-pulse pump 266 nm YAG laser and continuous low-power probe Ar ion beam were both focused into a supercritical water cell, giving a lensing signal whose strength could be maximized by changing the overlap of the two beams.