Aqueous mixtures of the poly(diallyldimethylammonium cation) ( p DADMA + ) and the fluorescent anionic dye Alexa Fluor® 546 (A546) are characterized using multiple fluorescence spectroscopy techniques. A546 and p DADMA + demonstrate binding interactions leading to the formation of noncovalent A546– p DADMA + complexes based on the quenching and recovery of A546 fluorescence emission intensity as a function of p DADMA + concentration. Fluorescence anisotropies of the mixtures support the results of fluorescence emission intensity analysis and yield a sub‐micromolar equilibrium dissociation constant for the complexes indicating that strong attractive electrostatic interactions produce complexation. Fluorescence correlation spectroscopy (FCS) characterization of the complexes in solutions containing systematically varied concentrations of either chloride or carboxylate anions suggests chain dimension collapse of p DADMA + in the complexes and preferential binding of A546 anions to lower‐molecular‐weight complexes in solution. Comparison of these effects as a function of solution ionic strength produced by chloride, monocarboxylate and dicarboxylate anion addition indicates that carboxylate anions have significantly stronger binding interactions with p DADMA + than chloride ions. Differences in the binding of aliphatic carboxylate anions of different chain length with p DADMA + are attributed to differences in their hydrophobic interactions with the organic polymer chains of p DADMA + . Further FCS studies of noncovalent A546– p DADMA + complexes prepared from narrow‐molecular‐weight fractions of p DADMA + hold the promise of deeper insights into the binding behaviors and hydrodynamic size variability of this industrially important polyelectrolyte. © 2025 Society of Chemical Industry.

The adsorption of molecular ions from aqueous solutions onto colloidal silica is utilized across a wide range of technologies. Measurement of such interactions using attenuated total reflectance/Fourier transform infrared (ATR/FT-IR) spectroscopy presents challenges due to the instability of colloidal silica particle films on an ATR's diamond crystal internal reflection element (IRE). Here, the instability of silica is addressed by first depositing a thin film of colloidal ceria particles on the IRE to improve silica's adhesion. This enables the application of ATR/FT-IR spectroscopy to characterize the adsorption of quaternary ammonium ions, including the poly(2-(trimethylamino)ethyl methacrylate) (pTMAEM) and compounds modeling pTMAEM's side chain functional groups, tetramethylammonium (TMA) and acetylcholine (AChl) ions, on low- and high-silanol density silica films at varying pH values. Density functional theory (DFT) calculations are performed to model the TMA-silica and pTMAEM-silica complexes and predict their infrared (IR) spectra. The adsorption of TMA, AChl, and pTMAEM to silica is demonstrated by IR bands in the range of 950-1250 cm-1, which were dominated by transverse optical and longitudinal optical phonon modes. Langmuir adsorption constants based on optical phonon modes indicate that TMA is more strongly adsorbed to the low-silanol density films, whereas pTMAEM shows a stronger adsorption to silica overall, regardless of the silanol density. This suggested that both electrostatic and nonelectrostatic interactions contribute to TMA's adsorption, while the polymeric nature of pTMAEM enabled adsorption due to strong electrostatic interactions via multiple adsorption events. AChl's relatively weak adsorption to silica prevented the calculation of a Langmuir adsorption constant; however, the IR spectra suggested any adsorption was primarily due to the quaternary ammonium ion. The application of ATR/FT-IR spectroscopy in combination with DFT allowed a complete characterization of the adsorption of the quaternary ammonium ion onto ceria-supported colloidal silica, which may also be applied to other molecular ions, further characterizing and optimizing technologies employing similar materials.

Based on the growing range of applications for polycations in research and commercial materials, a continuing need exists to advance the fundamental knowledge and understanding of this class of materials. Spectroscopic and solution properties characterizations of noncovalently labeled, fluorescent Alexa Fluor® dye complexes of two commercial polycations, poly(2-(trimethylamino) ethyl methacrylate) monocation and poly[bis[2-chloroethyl] ether-alt-1,3-bis[3-(dimethylamino) propyl] urea] dication are reported to help address this need. A variety of fluorescence spectroscopic methods are used with a special emphasis on fluorescence correlation spectroscopy (FCS) which is applied to characterize the Stokes radius (RS) and equilibrium dissociation constants (Kd) of dye-polycation complexes at nanomolar dye concentrations. Resulting RS values indicate dye binding to individual polycation chains. Measured Kd values in the sub-micromolar range are consistent with strong dye binding. Increasing solution ionic strength with sodium chloride addition inhibits dye binding and decreases the RS of dye-polycation complexes due to size collapse of polycation chains. The complexes differ in their solution stability to ionic strength changes suggesting that both electrostatic and hydrophobic binding interactions influence dye binding. This study establishes the viability of noncovalent dye-polycation complexation in concert with FCS characterization as a general approach for investigating the properties of quaternary ammonium ion containing polycations in aqueous solution.

The preparation and properties of surfactant micelles labeled with the dye, Nile Red (NR), are described. Fluorescence emission and excitation spectroscopy establish the localization of NR in the hydrophobic core of nonionic Brij (R) S10, Brij (R) S20, and Triton X-100 micelles, and in ionic mixed micelles prepared from sodium dodecyl sulfate (SDS) and Triton X-100 mixtures of varying composition. Stokes diameter analysis of NR-micelles by fluorescence correlation spectroscopy (FCS) yields mean diameters ranging from 3.0 to 10.6 nm depending on the surfactant composition and its concentration used for micelle preparation. Adsorption of NR-micelles on a 20 nm, charged-stabilized, sol-gel silica nanoparticle is characterized by FCS. NR-micelle-nanoparticle solutions are analyzed as two-species mixtures of free and nanoparticle-bound NR-micelles allowing determinations of mean Stokes diameters and fractions of nanoparticle-bound NR-micelles. Incorporation of SDS into nonionic Triton X100-NR-micelles progressively diminishes the adsorption of the mixed ionic NR-micelles on the nanoparticles with increasing SDS in the micelles. FCS analysis NR-micelle adsorption interactions with silica nanoparticles is shown to occur at the single NR-micelle level, providing a means for advancing the fundamental understanding of these interactions. The kinetics of a NR-micelle's penetration into a hydrated fumed silica determined by FCS are shown to be a one-dimensional Fickian process and indicative of pores with low tortuosity. The use of NR

Intermolecular interactions in buffered aqueous solution between the polycation, poly(2-(trimethylamino)ethyl methacrylate) chloride (pTMAEMC) and two anionic xanthene dyes, 2', 7'-difluorofluorescein (Oregon Green 488) and 2, 4, 5, 7-tetraiodofluorescein (Erythrosin B), are characterized using multiple optical spectroscopic methods. Visible absorption spectroscopy indicates the formation of ground-state pTMAEMC-dye complexes. Benesi-Hildebrand binding isotherm analysis of visible absorption spectra for pTMAEMC-dye mixtures quantifies the strength of binding interactions producing the complexes. For both Oregon Green 488 (OG) and Erythrosin B (EB) in mixtures with pTMAEMC, the concentration of the solution's sodium acetate buffer at a fixed pH alters the binding constants, Kb, suggesting that ionic strength plays a key role in determining the binding affinity of pTMAEMC for the dyes. Comparison of Kb, for the dyes indicates stronger binding of EB under all solution conditions. Steady-state fluorescence emission spectroscopy, fluorescence quenching, excited-state fluorescence lifetime measurements and fluorescence correlation spectroscopy provide complementary data for the interactions between pTMAEMC and the dyes. Mixtures of pTMAEMC with the dyes produce fluorescence enhancements and fluorescence quenching which exhibit a dependence on the buffer concentration used in the mixture. Excited-state lifetime analysis indicates that OG interacts with pTMAEMC through ground-state interactions while EB exhibits both ground-state and excited-state interactions with pTMAEMC. The spectroscopic measurements suggest that a polyelectrolyte effect for pTMAEMC due to ionic strength variation produced by the buffer concentration affects the dye binding profile of the polycation. This conclusion is supported by fluorescence correlation spectroscopy (FCS) analyses of the hydrodynamic diameter changes in pTMAEMC-OG binding in low buffer concentration (low ionic strength) solution. FCS analyses of pTMAEMC-OG mixtures also reveal diversity in the complexes formed in low ionic strength solution suggesting that other xanthene dyes will exhibit similar binding behaviors in mixtures with pTMAEMC as a function of solution ionic strength.

The performance of chemical-mechanical planarization (CMP) slurries in the commercial fabrication of integrated circuits depends critically on the physical and chemical properties of abrasive particles used in CMP slurries. A host of analytical methods are used for characterizing the properties of CMP abrasive particles including spectroscopic,1,2 sedimentation,3 viscometric4 and fractionation5 techniques. One particular method, fluorescence correlation spectroscopy (FCS),1 has demonstrated significant versatility in this application due to its ability to simultaneously analyze the particle size distribution and the surface chemistry of abrasive particles in aqueous mixture containing small molecule CMP additives. The need for further characterization of these properties, especially the surface chemistry, is the product of the increasing use of nano-abrasives with reduced hydrodynamic diameters (< 20 nm) in CMP slurries in order to minimize surface defect creation during CMP processes. Incorporation of nano-abrasives in CMP slurries will promote surface chemistry-driven CMP additive adsorption on abrasive particles due to the increase in the total particle surface area as the hydrodynamic diameters of nano-abrasives decrease. The use of FCS in conjunction with the application of complementary techniques, such as dynamic light scattering and fluorescence lifetime analysis, is described in the presentation for the comprehensive characterization of the physical and chemical properties of representative silica abrasives used in CMP slurries. 1. Jacobson, L.M.; Turner, D.K.; Wayman, A.; Rawat, A.; Carver, C.T..; Moinpour, M.; Remsen, E.E. “Characterization of Particle Size and Surface Adsorption for SiO2 Abrasives Used in Chemical Mechanical Planarization via Fluorescence Correlation Spectroscopy”, ECS J. Solid State Sci. Tech. 2015, 4, P5053-P5057. 2. Marsh, J.L.; Wayman, A.E.; Smiddy, N.M.; Campbell, D.J.; Parker, J.C.; Bosma, W.B.; Remsen, E.E. “Infrared Spectroscopic Analysis of the Adsorption of Pyridine Carboxylic Acids on Colloidal Ceria”, Langmuir 2017, 33 , 13224-13233. 3. Kamiti, M.; Boldridge, D.; Ndoping, L.M.; Remsen, E.E. “Simultaneous Absolute Determination of Particle Size and Effective Density of sub-Micron Colloids by Disc Centrifuge Photosedimentometry”, Anal. Chem. 2012, 84, 10526−10530. 4. Boldridge, D.; Kamiti, M.; Remsen, E.E. “Avoiding the Spherical Particle Assumption: Fractal Particle Density, Size and Structure Characterization through Combined Sedimentation and Viscometry Measurements”, Anal. Chem. 2020, 92, 15034-15041. 5. Williams, S.K.R.; Park, I.; Remsen, E.E.; Moinpour, M. “New Particle Metrology for CMP Slurries”, Mater. Res. Soc. Symp. Proc. 2007, 991, 249-251.

Small molecule adsorption on CMP slurry abrasive particles has been investigated previously for silica (1) and ceria (2, 3) abrasives using fluorescence correlation spectroscopy (FCS) and attenuated total reflectance – Fourier transform infrared spectroscopy (ATR-FTIR). The need for further characterization of such adsorptive interactions is dictated by the increasing use of abrasive particles in CMP slurries with minimized hydrodynamic diameters (≤ 10 nm) as a means to reduce surface defects created during CMP processes. Incorporation of ever-smaller abrasive particles in CMP slurries will, however, promote the adsorption of chemical additives on a slurry’s abrasive particles due to the increase in the total abrasive particle surface area. In the present study, FCS and ATR-FTIR are employed in the analysis of small molecule adsorption on colloidal alumina and zirconia abrasive particles. This work is motivated by the widespread commercial use of alumina-based slurries in CMP processes for planarization of deposited copper films on dielectric layers and the proposed use (4) of zirconia abrasives in CMP slurries for metal film removal on dielectric metal oxide materials. The reported FCS studies use fluorescent dyes as probes for adsorption sites on alumina and zirconia colloids dispersed in aqueous solution. Described ATR-FTIR analyses summarize the characterization of molecular interactions driving glycine and picolinic acid adsorption on porous thin films of colloidal alumina and zirconia, respectively. The potential for employing these methods in studies modelling the adsorption of CMP slurry additives on a metal film deposited on a silicon wafer surface is also discussed. References: Jacobson, L.M.; Turner, D.K.; Wayman, A.; Rawat, A.; Carver, C.T..; Moinpour, M.; Remsen, E.E. Characterization of Particle Size and Surface Adsorption for SiO2 Abrasives Used in Chemical Mechanical Planarization via Fluorescence Correlation Spectroscopy. ECS J. Solid State Sci. Tech. 2015, 4, P5053-P5057. Schorr, D.K.; Smith, M.A.; Rawat, A.K.; Carver, C.T.; Mansour, M.; Remsen, E.E.Fluorescence Correlation Spectroscopic Studies of Particle Properties for Colloidal Ceria Abrasives Used in Chemical-Mechanical Planarization. ECS Trans. 2016, 72, 43-51. Marsh, J.L.; Wayman, A.E.; Smiddy, N.M.; Campbell, D.J.; Parker, J.C.; Bosma, W.B.; Remsen, E.E.Infrared Spectroscopic Analysis of the Adsorption of Pyridine Carboxylic Acids on Colloidal Ceria.Langmuir 2017, 33 , 13224-13233. “CMP Composition Containing Zirconia Particles and Method of Use”; Lin, Wiechang; Parker, John; Remsen, Elizabeth; PCT Int. Appl. 2012; US 8,778,212 B2; July 15, 2014.

Physically meaningful characterization of irregularly shaped particles continues to present substantial challenges to the experimentalist. "Equivalent diameters" based on experimental techniques such as static and dynamic light scattering or sedimentation have proliferated to the point that they are often no longer recognized as equivalent. This study demonstrates the use of dual-fluid disk centrifuge photosedimentometry coupled with rheological measurements of viscosity to provide direct insights into both the average mass of a structured particle size distribution and the average hydrodynamic diameter.

Nanoscale fluorescent probes are of great importance due to their capabilities for imaging on multiscale. Herein, we report the first synthesis of structurally well-defined nanoparticulate "oligodots" developed for multicolor imaging in vitro and in vivo. These nanoparticles are prepared via condensation and curing reactions where the engineering of the solvent results in the nanoparticles with green (λem = 550 nm) and red (λem = 650 nm) emission range. Differences found in the photophysical properties have been attributed to variations in oligomeric compositions produced during the synthesis as was corroborated by extensive physicochemical characterizations. Specifically, mass spectroscopy provided a picture of the formed species during the synthesis. The feasibility of the oligodots for multicolor imaging is demonstrated both in vitro and in vivo. The red-emitting oligodot is employed for dynamic whole-body imaging in mice. It is envisioned that oligodots would enable multicolor imaging of various biomarkers in complex diseases such as cancer where numerous molecular and metabolic phenotypes work in concert in their emergence.

RationaleOver the last ten years, helium direct analysis in real time time‐of‐flight mass spectrometry (He DART‐TOFMS) has become an established technique in rapid screening of forensic drugs to decrease the time necessary to triage forensic drug cases, therefore contributing to backlog reduction and more timely criminal prosecution. Recently, we demonstrated that N2 DART was able to efficiently ionize all polar compounds except for a few extremely small ones such as methanol and acetonitrile. Therefore, N2 DART‐TOFMS should be a suitable technique for rapid screening of forensic drugs.MethodsNitrogen direct analysis in real time time‐of‐flight mass spectrometry (N2 DART‐TOFMS) was performed using a JEOL AccuTOF mass spectrometer with an IonSense DART‐100 ion source. A 3‐min analytical protocol was used for the analysis of each sample. Sample introduction was accomplished by moving the closed end of a melting point capillary where approximately 1 μL sample solution was deposited or the exposed inside of a freshly cut tablet across the N2 gas stream between the DART‐100 ion source and orifice 1 of the AccuTOF.ResultsTen commonly abused drugs, eight synthetic cannabinoids and four controlled prescription drugs (CPDs) were analyzed. The limit of detection (LOD) was determined to be approximately 10 μg/mL or 10 pg in quantities. All drugs at the LOD level were positively identified using their [M + H]+ ions with mass errors less than 5 mDa. The identification were further supported by in‐source fragment ions and characteristic N2 DART ions that are not commonly generated by He DART, e.g. [M + H + O]+ and [M + H + 2O]+ ions.ConclusionsIt was concluded that the 3‐min analytical protocol could be utilized in the analysis of seized drugs in the form of tablets and powders or prepared in solution. In consideration that N2 is readily available in the air and He is a non‐renewable resource, N2 DART‐TOFMS is a greener, cheaper and more convenient alternative to He DART‐TOFMS in rapid screening of forensic drugs.

Nitrogen can be an inexpensive alternative to helium used by direct analysis in real time (DART), especially in consideration of the looming helium shortage. Therefore, the ionization mechanism of positive-ion N2 DART has been systematically investigated. Our experiments suggest that a range of metastable nitrogen species with a variety of internal energies existed and all of them were less energetic than metastable helium atoms. However, compounds with ionization energies (IE) equal to or lower than 10.2 eV (all organic compounds except the extremely small ones) can be efficiently ionized. Because N2 DART was unable to efficiently ionize ambient moisture and common organic solvents such as methanol and acetonitrile, the most important ionization mechanism was direct Penning ionization followed by self-protonation of polar compounds generating [M+H]+ ions. On the other hand, N2 DART was able to efficiently ionize ammonia, which was beneficial in the ionization of hydrogen-bonding compounds with proton affinities (PA) weaker than ammonia generating [M+NH4]+ ions and large PAHs generating [M+H]+ ions through proton transfer. N2 DART was also able to efficiently ionize NO, which led to the ionization of nonpolar compounds such as alkanes and small aromatics generating [M–(2m+1)H]+ (m=0,1…) ions. Lastly, metastable nitrogen species was also able to produce oxygen atoms, which resulted in increased oxygen adducts as the polarity of organic compounds decreased. In comparison with He DART, N2 DART was approximately one order of magnitude less sensitive in generating [M+H]+ ions, but could be more sensitive in generating [M+NH4]+ ions.

Fusarium verticillioides is a fungal pathogen that commonly infects the stalk, ear, and kernels of corn and can produce fumonisins, a family of mycotoxins linked to disease in livestock and humans. Our goal is to characterize the role of the disaccharide trehalose in growth and stress response in F. verticillioides. Trehalose synthesis in fungi occurs via two steps, the first catalyzed by trehalose‐6‐phosphate synthase (TPS), and the second by trehalose‐6‐phosphate phosphatase (TPP). Previously, we found that trehalose synthesis is completely abolished in a strain lacking TPS, encoded by the TPS1 gene. We report here that mutant strains lacking either one (ΔTPS2) or both (ΔTPS2/ΔTPS3) of the putative TPP genes in F. verticillioides retain the ability to produce trehalose, albeit at reduced levels. The effects of osmotic and thermal stress on these mutants are being investigated.

Surface adsorption of a homologous series of pyridine carboxylic acids on a hydrated colloidal cerium dioxide (ceria) film is characterized using the combination of experimental and computationally determined infrared (IR) spectra. Experimental analyses employ attenuated total reflectance (ATR) IR spectroscopy of deposited colloidal ceria thin films equilibrated with three pyridine carboxylic acids at pH 3.0, 5.5, and 8.5. The corresponding computational IR spectra for the energy-minimized intermediate and base forms of the pyridine carboxylic acids use density functional theory calculations at the B3LYP/6-311++G** level of theory. Solvent effects are modeled using both the COSMO implicit solvation model and the inclusion of explicit water molecules. Experimental IR spectra show that the adsorptive interactions between the pyridine carboxylic acids and ceria surface are due to the outer-sphere coordination of cerium ions in the films. Vibrational assignments based on combined experimental and computational results indicate that both pyridyl ring nitrogen and carboxylate functional groups account for the interaction of pyridine carboxylic acids at ceria surfaces. Experimentally determined Langmuir constants point to the intermediate form of picolinic acid (pyridine-2-carboxylic acid) as having the strongest adsorption to ceria compared to the other pyridine carboxylic acids investigated. The enhanced adsorption of picolinic acid is attributed to the adjacency of the protonated pyridyl nitrogen and the carboxylate group relative to nicotinic acid (pyridine-3-carboxylic acid) and isonicotinic acid (pyridine-4-carboxylic acid).

Fluorescence correlation spectroscopy (FCS) has been demonstrated as a versatile technique for the analysis of the smallest size fraction (diameter < 20 nm) of an abrasive silica particle dispersion and for small molecule adsorption on these particles (1-3). The technique employs the adsorption of a fluorophore at an abrasive particle’s surface, followed by single-particle detection of the dye-bound abrasive particle. Subsequent evaluation of the diffusion coefficients for all fluorescent species in the abrasive dispersion enables the quantitative determination of the fraction of adsorbed and non-adsorbed dye molecules. In the present study, the FCS method is extended to the analysis of particle size distributions of smaller-sized colloidal ceria CMP abrasives and the quantitative characterization of dye adsorption on ceria particles. This application of FCS reflects the growing commercial importance of ceria-based slurries in CMP processes, such as shallow trench isolation (STI), which rely on both mechanical and chemical mechanisms in the CMP process 4 . Adsorption of the high quantum yield dye, Rhodamine 110 (R110), on ceria abrasive particles is shown to render the particles fluorescent for abrasives as small as 10 nm in hydrodynamic diameter. The sizing of particles in this diameter range is often problematic for a number of commonly employed techniques, such as static laser light differential centrifugal sedimentation. The FCS approach is demonstrated to have the additional advantage of being a single-particle technique which enables sizing determinations at nanomolar concentrations of fluorescently tagged ceria particle dispersions. Because dye molecules adsorb at specific sites on the particles, the technique provides a window on the surface chemistry of abrasive ceria particles. This characterization is discussed in conjunction with the FCS analysis of competitive adsorption of R110 and a widely employed CMP slurry additive, picolinic acid, which is used in STI processes. Further enhancements of the FCS technique for the characterization abrasive ceria dispersions, such as particle size distribution determination via the method of maximum entropy (MEM-FCS) and the use of the photon counting histogram (PCH) technique for the determination of molecular brightness of dye-bound particles as a metric for quantitative adsorption analysis are discussed. References Moinpour, M.; Wayman, A.; Rawat, R.; Carver, C. T.; Remsen, E. E. Surface Adsorption of CMP Slurry Additives on Abrasive Particles. ECS Trans. 2013, 52, 489-494. Jacobson, L.M.; Turner, D.K.; Rawat, A.; Carver, C.T.; Tripathi, A.; Moinpour, M.; Remsen, E.E. Application of Fluorescence Correlation Spectroscopy in the Characterization of Particle Size Distributions of Colloidal Silica Abrasives Used in Chemical-Mechanical Planarization. ECS Trans. 2014, 61, 55-63. Jacobson, L.M.; Turner, D.K.; Wayman, A.; Rawat, A.; Carver, C.T..; Moinpour, M.; Remsen, E.E. Characterization of Particle Size and Surface Adsorption for SiO 2 Abrasives Used in Chemical Mechanical Planarization via Fluorescence Correlation Spectroscopy. ECS J. Solid State Sci. Tech. 2015 , 4, P5053-P5057. Carter, P. W.; Johns, T. P. Interfacial Reactivity between Ceria and Silicon Dioxide and Silicon Nitride Surfaces: Organic Additive Effects. Electrochem. Solid-State Lett. 2005, 8, G218–G221.

Direct analysis in real time – time of flight – mass spectrometry (DART-TOF-MS) and size-exclusion chromatography (SEC) are used to analyze carbohydrates inF. verticillioides, such as trehalose.

Fluorescence correlation spectroscopy (FCS) is shown to be an effective characterization tool in the analysis of silica abrasives used in CMP slurries. Tagging of silica particles via non-covalent adsorption of a highly fluorescent dye is the key step in applying the technique to these materials. FCS is shown to have ample analytical sensitivity to detect and analyze the smallest fraction (< 20 nm) of an abrasive silica dispersion. Fractionation of abrasive silica dispersions using preparative ultracentrifugation allows a direct comparison of FCS and dynamic light scattering (DLS) methods for sizing particles with diameters less than 20 nm in the dispersion. The sensitivity of FCS measurements of this type exceeded the sensitivity of DLS determinations in this size range. Non-covalent adsorption of a fluorescent dye by the silica particle enables the characterization of adsorption behaviors of CMP slurry additives, such as benzotriazole (BTA) and amino acids, on abrasive silica particles. Different adsorption behaviors are observed and the use of one specific fluorescent dye, Rhodamine 110, afforded a determination of a quantitative isotherm for dye adsorption. Future applications of the FCS method for sizing abrasive nano-particles and adsorption isotherm analysis of other CMP abrasives, such as alumina and ceria, are proposed. (C) 2015 The Electrochemical Society. All rights reserved.

Applications of novel thin film electrodes are enabling the development of new commercial products ranging from in vivo biosensors, solar cells, and lithium-ion energy storage. A critical consideration that enables informed engineering of working devices is mass transport of electro-active species (EAS) and electrolytes within porous thin film electrodes. Initially we focus on the fabrication and characterization of transport within thin film electrodes fabricated from titanium dioxide, hydrogen titantate nanotubes, and zinc oxide via a sol-gel method. Characterization data for films deposited on indium tin oxide coated glass slides by doctor blade techniques are also discussed and include bright field microscopy, powder x-ray diffraction and, mass transport properties as investigated by cyclic voltammetry. Additionally we will discuss the creation and characterization of graphene nanosheets via the reduction of graphite oxide.

Advances in the use of a single-molecule spectroscopic method, fluorescence correlation spectroscopy (FCS), for the determination of the particle size distribution (PSD) of fine dispersions of colloidal silica and ceria abrasive particles employed in CMP slurries are described. The Maximum Entropy Method (MEM) is shown to be an effective approach for PSD analysis using FCS data for fluorescently dyed abrasive particles. FCS also provides an analysis of absorption phenomena on CMP abrasive particles using a fluorescent dye for the quantitative determination of adsorption isotherms. Extension of the FCS technique to the characterization of the adsorption of CMP slurry additive to colloidal silica and ceria abrasives is proposed.