Flight Secondary Ion Mass Spectrometry Research Articles

Microscopic and elemental analysis of temperature-induced changes in sulfur/silicon nitride stack-passivated Si surface

Sulfur passivation of different Czochralski Si surfaces along with hydrogenated amorphous silicon nitride capping layer has been reported. The effect of capping layer thickness and deposition temperature on sulfur reacted surface has a strong effect on initial passivation quality and its stability. Sulfur passivation on phosphorus diffused n-type textured Czochralski Si wafers capped with a 100 nm stacked hydrogenated amorphous silicon nitride layer demonstrates improved stability under heat and light with saturation current density <80 fA/cm2. A stack layer of a low temperature (≤300OC) hydrogenated amorphous silicon nitride followed by a high temperature (≈ 450OC) hydrogenated amorphous silicon nitride is adopted to achieve good thermally stable surface passivation. Sulfur-passivation with only a low temperature hydrogenated amorphous silicon nitride capping layer exhibits unstable behavior after thermal treatment due to blister/pinhole formation at ≥300OC and possible oxidation of the S-passivated surface. Photoluminescence imaging shows increased defect recombination loss due to disrupted surface passivation after thermal treatment. Fourier transform infrared spectroscopic studies demonstrate that these blister formations were caused by hydrogen effusion from Si–H and N–H bonds dissociation upon thermal processing. Time of flight secondary ion mass spectroscopy exhibits oxidation of S-reacted surface after thermal treatment that degrades the passivation quality.

Selective control of surface characteristics of magnesite and quartz by a novel silicophilic collector stearylamine acetate

Reverse flotation desiliconization from magnesite is significant for the exploitation of complex and barren magnesite resources. In this process, a critical issue is to find efficient and selective chemicals as flotation collectors. Herein, a cationic surfactant stearylamine acetate (SAA) was first used as a collector for the separation of magnesite and quartz. Micro-flotation experiments demonstrate that quartz can be separated from magnesite with a high Gaudin’s selectivity index of 6.51 at slurry pH 5.0 and 70 mg/L SAA. Measurements of zeta potential and contact angle show that SAA selectively increased the surface charge and hydrophobicity of quartz. Field emission scanning electron microscopy (FESEM/EDS) and atomic force microscope (AFM) imaging indicate greater adsorption density of SAA on quartz than magnesite, with significantly higher nitrogen element content and RMS surface roughness of quartz. We also used surface-sensitive time of flight secondary ion mass spectrometry (TOF-SIMS) and FTIR spectroscopy to characterize the selective adsorption of SAA on quartz from quartz-magnesite mixtures. Apart from electrostatic attraction, it is found that the selective adsorption was attributed to hydrogen bonding formed between the −N–H group of SAA and the oxygen atom of the O-Si-O group on quartz surface.

Study on the interstitial oxygen diffusion to understand the reduction of cryogenic RF loss for the superconducting radio-frequency niobium cavities

Abstract Medium-temperature baking (Mid-T baking) is an innovative method employed to enhance the unloaded quality factor Q0 of superconducting radio-frequency (SRF) niobium (Nb) cavities at cryogenic temperatures. This study presents an interstitial oxygen diffusion model based on the decomposition of the natural oxide to clarify the improved performance of the Nb cavities after undergoing Mid-T baking. Additionally, the correlation between the interstitial oxygen within the RF penetration depth and the surface resistance of the Nb cavities has been explored. The parameter for the oxide decomposition was determined using in-situ X-ray photoelectron spectroscopy (XPS), where the thickness of the oxide/carbide layer was calculated from the peak fitting of Nb 3d spectra and the attenuation law of the photoelectron beam. The interstitial oxygen diffusion model, validated by the semi-quantitative distribution along the depth determined by Time of Flight Secondary Ion Mass Spectrometry (ToF-SIMS), quantifies the oxygen atomic concentration within the RF penetration depth in Mid-T baked Nb material. In the baking temperature range of 300~400 ℃, the calculated oxygen concentration from the interstitial oxygen diffusion model demonstrates a more pronounced dependence on the baking temperature than the baking time. This suggests that more precise control of the interstitial oxygen concentration can be achieved by adjusting the baking temperature. Furthermore, it has been observed that maintaining a uniform and moderate oxygen concentration throughout the depth is essential for optimal BCS resistance. This study paves the way for more efficient processing optimization and enhancing understanding of the mechanism behind RF loss in Nb cavities.

Gradient conducting polymer surfaces with netrin-1-conjugation promote axon guidance and neuron transmission of human iPSC-derived retinal ganglion cells

Major advances have been made in utilizing human-induced pluripotent stem cells (hiPSCs) for regenerative medicine. Nevertheless, the delivery and integration of hiPSCs into target tissues remain significant challenges, particularly in the context of retinal ganglion cell (RGC) restoration. In this study, we introduce a promising avenue for providing directional guidance to regenerated cells in the retina. First, we developed a technique for construction of gradient interfaces based on functionalized conductive polymers, which could be applied with various functionalized ehthylenedioxythiophene (EDOT) monomers. Using a tree-shaped channel encapsulated with a thin PDMS and a specially designed electrochemical chamber, gradient flow generation could be converted into a functionalized-PEDOT gradient film by cyclic voltammetry. The characteristics of the successfully fabricated gradient flow and surface were analyzed using fluorescent labels, time of flight secondary ion mass spectrometry (TOF-SIMS), and X-ray photoelectron spectroscopy (XPS). Remarkably, hiPSC-RGCs seeded on PEDOT exhibited improvements in neurite outgrowth, axon guidance and neuronal electrophysiology measurements. These results suggest that our novel gradient PEDOT may be used with hiPSC-based technologies as a potential biomedical engineering scaffold for functional restoration of RGCs in retinal degenerative diseases and optic neuropathies.

Comprehensive Characterization of Porous Transport Electrodes with SEM, XPS, and Tof-SIMS

Advancements towards more efficient design and manufacturability of polymer electrolyte membrane electrolyzers include recent efforts to better integrate the porous transport layer (PTL) and adjacent anodic catalyst layer (CL), forming the porous transport electrode (PTE). It is well known that characterizations of the PTL alone, especially when combined with a protective coating, present numerous challenges. The PTE structure is even more complex, and it is difficult to comprehensively characterize all components and interfaces. In prior work, we established Time of Flight Secondary Ion Mass Spectrometry (ToF-SIMS) as a characterization technique for the PTLs coated with protective coatings. This work demonstrates ToF-SIMS as a powerful technique for the characterization of PTLs integrated with CLs. A series of sintered Ti PTLs were first coated with protective Pt coatings and then coated with various IrOx and IrRuOx catalysts via electrodeposition. Prepared PTE samples ranged in catalyst loadings and catalyst composition. Selected samples were also subjected to annealing post-treatments to further modify catalyst composition. X-ray photoelectron spectroscopy (XPS) was conducted to identify surface chemical speciation and states of the catalysts. ToF-SIMS analysis was conducted using Cs in both positive and negative modes to identify chemical species, including Ir, Ru, and their oxides as a function of catalyst layer depth. These two methods were complemented by Scanning Electron Microscopy and Energy Dispersive X-ray Spectroscopy (SEM- EDS) analysis to evaluate morphology and distribution of catalysts. This comprehensive physical and chemical characterization of the PTEs provides insights that are useful for the characterization of as produced, modified, and degraded PTE samples.

Enhancement of anti-oxidation and tensile strength of nanotwinned Cu foils by preferential Ni electrodeposition

In this study, Ni was employed to enhance the mechanical properties of nanotwinned copper (NT-Cu) foils due to its excellent oxidation resistance and compatibility with Cu. The tensile strength of the NT-Cu foils was enhanced 12.6 % (752.8 to 847.3 MPa) by Ni co-electrodeposition. During the electroplating, it was found that Ni ions inhibited the Cu growth, causing the reduction potential (overpotential) to shift in the negative direction. It resulted in a reduced deposition rate and decreased the twin spacing of the foils. Additionally, Ni ions acted as impurities for the grain refinement. Time of flight secondary ion mass spectrometry (TOF-SIMS) results indicated that Ni atoms were deposited on the top and bottom of the foils due to the limiting current density of Ni. The NT-Cu-Ni exhibited low roughness and performed superior resistance to oxidation compared to the NT-Cu. X-ray photoelectron spectroscopy (XPS) was also utilized to characterize the oxidation of the Cu (Ni) alloys. These mechanisms contributed to high strength, low resistivity, and excellent oxidation resistance of the NT-Cu-Ni foils for future battery materials.

Physico-chemical characterization of polyimide passivation layers for high power electronics applications

Silicon carbide (SiC) is a wide bandgap semiconductor suitable for high-voltage, high-power and high-temperature applications. However, the production of advanced SiC power devices still remains limited due to some shortcomings of the dielectric properties of the passivation layer. Thanks to their high operating temperature and dielectric strength, spin coated polyimide (PI) layers are considered ideal candidates for SiC devices passivation and insulation. In this view, a robust methodology for the physico-chemical characterization of such PI layers is required. Thanks to the use of time of flight-secondary ion mass spectrometry (ToF-SIMS), a SIMS-based surface-sensitive technique that provides specific identification of molecules, it was possible to distinguish different types of PIs employed in commercial SiC devices and postulate their molecular structure. This was obtained after careful selection of the analytical conditions used for the characterization of the specimens.The results attained in this study open the way for further improvements in one of the most key issues in the development of higher SiC power devices.

Depth profile study of LaAl1‐xCrxO3/SrTiO3 (x = 0, 0.2, 0.6, and 1) using time of flight secondary ion mass spectrometry (TOF‐SIMS)

The conducting two‐dimensional electron gas (2DEG) behavior in LaAlO3 (LAO)/SrTiO3 (STO) and their associated mechanisms from various aspects have brought tremendous attention in the concerned area of research. To correlate the 2DEG behavior with their compositions, we have performed time of flight secondary ion mass spectrometry (TOF‐SIMS) depth profile analysis of thin films of Cr‐doped LAO/STO system as LaAl1‐xCrxO3 (x = 0, 0.2, 0.6 and 1) deposited over TiO2 terminated STO substrate, which includes two parent compounds LAO/STO (metallic) and LCO/STO (insulating). The uniform decrease of La and Al concentration at the interface of LAO/STO (metallic) system and in the contrary the nonuniformity of La and Cr concentration in LCO/STO (insulating) system have been highlighted. The uniform variation of ionic concentration at the interface of LAO/STO may increase the career concentrations to make the system metallic. The upward and downward diffusion at the interfaces of intermediate compositions varies differently from their parent ones due to the mixing of Al and Cr. Our results may help to understand the conducting nature of LAO/STO system for future developments and applications in such system.

Progressive quenching of luminescence from quantum dot thin films in proximity with ZnMgO in unencapsulated stacks

ZnMgO nanoparticles (NPs) are being increasingly used as the electron transport layer (ETL) in state-of-the-art quantum-dot light-emitting devices (QLEDs) instead of ZnO. However, the impact of ZnMgO on the luminescence properties of quantum dots (QDs) is much less understood. Here, we compare ZnMgO and ZnO NPs for their quenching effect on Cd-based QDs photoluminescence (PL), immediately and over time. Time-resolved photoluminescence (TRPL) and steady-state PL results show that ZnMgO NPs decreases the QDs’ luminescence more than ZnO NPs and that the behavior continues progressively over time. The surface topography of the samples containing different ETLs is studied using atomic force microscopy (AFM) and optical PL images. Additionally, time of flight secondary ion mass spectroscopy (TOF-SIMS) measurements are conducted to investigate the potential diffusion of some species from ETL into the QDs layer. The results confirm that morphological changes and out-diffusion of some species from the ZnMgO layer can likely play a role in the QDs PL quenching. This study sheds light on the limitations of ZnMgO for the long-term stability of QLEDs, specifically for blue QLEDs where using ZnMgO is essential for efficient electron injection.

Matrices to enhance the ion yield of OLED molecules in ToF-SIMS: An interesting alchemist solution

Since the early days of time of flight secondary ion mass spectrometry (ToF-SIMS), increasing the ion signal has been crucial. It is even more crucial when performing tandem mass spectrometry experiments. To achieve this goal, many developments have been made over the years, which are divided into two categories: instrumental development and sample modification. The latter involves sample metallization, matrix deposition, or changing the temperature of the measurement. In this study, the possibility of using matrices to enhance the signals of organic light emitting device (OLED) molecules was explored. Seven molecules commonly used in OLEDs were separately deposited on Si wafers: Alq3, 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane, 1,4,5,8,9,11-hexaazatriphenylenehexacarbonitrile, Ir(mppy)3, N,N′-bis(naphthalene-1-yl)-N,N′-bis(phenyl)benzidine, 2,2′,7,7′-tetra(N,N-ditolyl)-amino-spiro-bifluor (STTB), and tris(4-carbazoyl-9-ylphenyl)amine. Using the same solvent, three different matrices with different thicknesses, common in matrix assisted light desorption ionization time of flight mass spectrometry, α-cyano-4-hydroxycinnamic acid, 2,5-dihydrobenzoic acid (DHB), and dihydrochloride N-(1-Naphthyl)ethylenediamine, were sprayed on these surfaces. Spectra were acquired for all compounds and spraying conditions in static ToF-SIMS experiments for Alq3 chemical imaging and depth profiling were performed. This allowed the investigation of the fragmentation pattern of the chosen matrices in ToF-SIMS and, thus, obtained a reference for these molecules. The results show that matrices can enhance the signal of fragments of the studied molecules, for example, the signal of STTB is increased with DHB spraying. Samples sprayed only with the solvent were also prepared to verify the impact of the matrices on the signal. Spraying with the solvent alone can enhance the signal even more than the matrices up to four times in the case of Alq3. This result opens new possibilities in the field of matrix-enhanced ToF-SIMS in terms of applications and matrix choices.

Microglial activation induces nitric oxide signalling and alters protein S-nitrosylation patterns in extracellular vesicles.

Neuroinflammation is an underlying feature of neurodegenerative conditions, often appearing early in the aetiology of a disease. Microglial activation, a prominent initiator of neuroinflammation, can be induced through lipopolysaccharide (LPS) treatment resulting in expression of the inducible form of nitric oxide synthase (iNOS), which produces nitric oxide (NO). NO post-translationally modifies cysteine thiols through S-nitrosylation, which can alter function of the target protein. Furthermore, packaging of these NO-modified proteins into extracellular vesicles (EVs) allows for the exertion of NO signalling in distant locations, resulting in further propagation of the neuroinflammatory phenotype. Despite this, the NO-modified proteome of activated microglial EVs has not been investigated. This study aimed to identify the protein post-translational modifications NO signalling induces in neuroinflammation. EVs isolated from LPS-treated microglia underwent mass spectral surface imaging using time of flight-secondary ion mass spectrometry (ToF-SIMS), in addition to iodolabelling and comparative proteomic analysis to identify post-translation S-nitrosylation modifications. ToF-SIMS imaging successfully identified cysteine thiol side chains modified through NO signalling in the LPS treated microglial-derived EV proteins. In addition, the iodolabelling proteomic analysis revealed that the EVs from LPS-treated microglia carried S-nitrosylated proteins indicative of neuroinflammation. These included known NO-modified proteins and those associated with LPS-induced microglial activation that may play an essential role in neuroinflammatory communication. Together, these results show activated microglia can exert broad NO signalling changes through the selective packaging of EVs during neuroinflammation.

Application of organic phosphonic acid dispersant in the separation and flotation of chalcopyrite and serpentine

The floatation of target minerals is often severely deteriorated in highly muddy mineral flotation systems. In this study, it was shown that the chalcopyrite recovery was significantly decreased due to the slime-coating of the serpentine fines. To enhance the floatability of chalcopyrite in the presence of serpentines, two phosphonic acids of 1-Hydroxyethylidene-1,1-diphosphonic acid (HEDP) and ethylenediamine tetramethylene phosphonic acid (EDTMP) were applied as dispersants in the floatation process. The micro-flotation tests indicated that HEDP and EDTMP could well eliminate the adverse effect of coated serpentine on the floatability of chalcopyrite. Adsorption tests and X-ray photoelectron spectra (XPS) analysis demonstrated that HEDP and EDTMP could selectively adsorb on the serpentine surface due to the chelation of phosphonic acid groups with the magnesium atoms on the serpentine surface, which was confirmed by the flight secondary ion mass spectrometry (TOF-SIMS) characterization. The zeta potential measurements showed that the adsorption of dispersants on serpentine changed the surface charges from positive to negative, while the zeta potential of chalcopyrite became more negative due to the dissolution of copper and iron cations from the chalcopyrite surface. Therefore, the electrostatic repulsion effectively prevented the slime-coating of serpentine on the chalcopyrite surface, which was also supported by the atomic force microscope (AFM) force measurements. As a result, the use of dispersants eliminated the adverse effects of serpentinite and greatly improved the floatability of chalcopyrite. The findings in this work indicate that the phosphonic acids of HEDP and EDTMP might find their application as effective dispersants to improve the floatability of target minerals in highly muddy mineral flotation systems.

Synergistic inhibition of Mikania micrantha extract with iodide ion on the corrosion of cold rolled steel in trichloroacetic acid medium

The corrosion inhibition behavior of Mikania micrantha extract (MME) and iodide ion in a synergistic system consisting of 0.10 M trichloroacetic acid (Cl3CCOOH, TCA) on cold rolled steel (CRS) materials and its mechanism was fully investigated by weightlessness, electrochemical, and surface analysis measurements. The results show that MME/I− performs higher inhibition than either MME or I− with a peak inhibition efficiency of 96.3 %. The adsorption of MME, I− and MME/I− on CRS follow with Langmuir isotherm. MME/I− retards both anodic and cathodic reactions. With the MME/I− complex inhibitor, the capacitance arc radius reaches a maximum. The results of scanning electron microscopy (SEM), atomic force microscopy (AFM), and confocal laser scanning microscopy (CLSM) showed that there were obvious adsorbent films on the surface of the suppressed CRS. Compositional analysis of surface adsorbates on CRS by X-ray photoelectron spectroscopy (XPS) and time of flight secondary ion mass spectrometry (TOF-SIMS) revealed that the main components of the adsorption film on the surface of CRS contained a large number of polar compounds, notably the formation of chemical bonds by iron atoms.

Suppressed Electrolyte Decomposition Behavior to Improve Cycling Performance of LiCoO2 under 4.6V through the Regulation of Interfacial Adsorption Forces.

Alleviating the decomposition of the electrolyte is of great significance to improving the cycle stability of cathodes, especially for LiCoO2 (LCO), its volumetric energy density can be effectively promoted by increasing the charge cutoff voltage to 4.6V, thereby supporting the large-scale application of clean energy. However, the rapid decomposition of the electrolyte under 4.6V conditions not only loses the transport carrier for lithium ion, but also produces HF and insulators that destroy the interface of LCO and increase impedance. In this work, the decomposition of electrolyte is effectively suppressed by changing the adsorption force between LCO interface and EC. Density functional theory illustrates the LCO coated with lower electronegativity elements has a weaker adsorption force with the electrolyte, the adsorption energy between LCO@Mg and EC (0.49eV) is weaker than that of LCO@Ti (0.73eV). Meanwhile, based on the results of time of flight secondary ion mass spectrometry, conductivity-atomic force microscopy, in situ differential electrochemical mass spectrometry, soft X-ray absorption spectroscopy, and nuclear magnetic resonance, as the adsorption force increases, the electrolyte decomposes more seriously. This work provides a new perspective on the interaction between electrolyte and the interface of cathode and further improves the understanding of electrolyte decomposition.

Superhydrophobicity wood with reversible photoresponsive property

Superhydrophobic photoresponsive wood (HPW) was synthesized through the vacuum pressure impregnation process with octadecyltrimethoxysilane (OTS), spiropyran, and polyvinyl alcohol (PVA). The process endowed the wood with photostimulation responsiveness and superhydrophobic characteristics. Scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), Time of Flight Secondary Ion Mass Spectrometry (TOF-SIMS), Fourier transform infrared spectroscopy (FTIR), and a contact angle meter were analyzed to determine the micromorphology, chemical composition, and hydrophobicity of the modified wood. The modified wood had a micro-nanometer mastoid structure at the microscopic level, with a large number of hydrophobic groups. The static water contact angle of the modified wood reached 153°, the water absorption rate decreased from 123.28 % to 19.29 %, and the anti-swelling rate was only 1.69 %, showing good hydrophobic and anti-swelling performance. At the same time, color values of the wood L*, a*, b*, and total color difference ΔE*, it was found that spiropyran made the modified wood have a rapid response to light stimulation.

Electron Donating Functional Polymer Dielectrics to Reduce the Threshold Voltage of n‐Type Organic Thin‐Film Transistors

AbstractLow‐cost and high‐performance electronics based on synthetically simple materials are required to fuel the deployment of smart packaging and wearable electronics. Metal phthalocyanines (MPcs) are promising semiconductors for use in n‐type organic thin film transistors (OTFTs) but often require high operating voltages. The first silicon phthalocyanine‐based OTFT with a polymer dielectric is reported as an alternative to traditional metal oxide dielectrics. Incorporating poly(methyl methacrylate) (PMMA) as the dielectric successfully reduces the threshold voltage (VT) of bispentafluorophenoxy SiPc (F10‐SiPc) from 14.9V to 7.3V while retaining high mobility. Further reduction in VT is obtained by using copolymers and blends of PMMA and dimethylamino ethyl methacrylate (DMAEMA)‐containing polymers, where a higher molar fraction of DMAEMA leads to a consistent drop in VT to ‐0.7 V. The electron‐donating groups of the tertiary amines in the DMAEMA show clear interfacial doping of the semiconductor, reducing the voltage required to populate the dielectric/semiconductor interface with charge carriers and turn on the device. Blending trace amounts of DMAEMA‐containing copolymers with PMMA proves to be an effective strategy for reducing the VT while keeping the charge mobility high, unlike when using pure copolymers with elevated DMAEMA content. Time of flight secondary ion mass spectroscopy (ToF‐SIMS) and X‐ray photoelectron spectroscopy (XPS) demonstrate that the DMAEMA‐containing copolymer is floating to the surface of the PMMA blend at the dielectric–semiconductor interface, which explains the reduced VT. Synchrotron scanning transmission X‐ray microscopy (STXM) demonstrates that PMMA promotes a more edge‐on orientation of F10‐SiPc films, compared to the more face‐on orientation when deposited on the DMAEMA containing copolymer. This study demonstrates a straightforward process for designing dielectric polymers and their blends for the reduction in VT for n‐type OTFTs.

Multi-spectroscopic characterization of organic salt components in medicinal plant

The characterization of structure of organic salts in complex mixtures has been a difficult problem in analytical chemistry. In the analysis of Scutellariae Radix (SR), the pharmacopoeia of many countries stipulates that the quality control component is baicalin (≥9% by high performance liquid chromatography (HPLC)). The component with highest response in SR was also baicalin detected by liquid chromatography-mass spectrometry (LC-MS). However, in the attenuated total reflection Fourier transform infrared spectroscopy, the carbonyl peak of glucuronic acid of baicalin did not appear in SR. The results of element analysis, time of flight secondary ion mass spectrometry, matrix assisted laser desorption ionization mass spectrometry and solid-state nuclear magnetic resonance all supported the existence of baicalin magnesium salt. Based on this, this study proposes an analysis strategy guided by infrared spectroscopy and combined with multi-spectroscopy techniques to analyze the structure of organic salt components in medicinal plant. It is meaningful for the research of mechanisms, development of new drugs, and quality control.

Dissolved organic carbon spurs bacterial-algal competition and phosphorus-paucity adaptation: Boosting Microcystis' phosphorus uptake capacity

Dissolved organic carbon (DOC) can alter the availability of background nutrients by affecting the proliferation of heterotrophic bacteria, which exerts a notable influence on algal growth and metabolism. However, the mechanism of how allochthonous DOC (aDOC) precipitates shifts in bacterial-algal interactions and modulates the occurrence of cyanobacteria blooms remains inadequately elucidated. Therefore, this study investigated the relationship between bacteria and algae under aDOC stimulation. We found that excess aDOC triggered the breakdown and reestablishment of the equilibrium between Microcystis and heterotrophic bacteria. The rapid proliferation of heterotrophic bacteria led to a dramatic decrease in soluble phosphorus and thereby resulted in the inhibition of the Microcystis growth. When the available DOC was depleted, the rapid death of heterotrophic bacteria released large amounts of dissolved phosphorus, which provided sufficient nutrients for the recovery of Microcystis. Notably, Microcystis rejuvenated and showed higher cell density compared to the carbon-absent group. This phenomenon can be ascribed that Microcystis regulated the compositions of extracellular polymeric substances (EPS) and the expression of relevant proteins to adapt to a nutrient-limited environment. Using time of flight secondary ion mass spectrometry (TOF-SIM) and proteomic analysis, we observed an enhancement of the signal of organic matter and metal ions associated with P complexation in EPS. Moreover, Microcystis upregulated proteins related to organic phosphorus transformation to increase the availability of phosphorus in various forms. In summary, this study emphasized the role of DOC in algal blooms, revealing the underestimated enhancement of Microcystis nutrient utilization through DOC-induced heterotrophic competition and providing valuable insights into eutrophication management and control.

Investigation of Iron Dissolution Mechanism in Acidic Solutions with and without Dissolved CO2—Part II: Time of Flight-Secondary Ion Mass Spectrometry 3D Mapping

Time-of-flight-secondary ion mass spectrometry (ToF-SIMS) 3D mapping and depth profiling were used to study the anodic iron dissolution mechanisms of mild steel in chloride-containing aqueous CO2 environments. The technique detected adsorbed hydroxide and chloride intermediates formed during the corrosion process, consistent with the proposed multipath reaction mechanism for anodic iron dissolution reaction. Despite the presence of aqueous carbonic species and their observed effect on the kinetics of iron dissolution, no additional adsorbed intermediates have been detected in aqueous CO2 environments, indicating that carbonic species do not directly participate in the iron dissolution reaction. ToF-SIMS 3D mapping results on characterization of the specimens immersed in a chloride-containing solution with and without CO2 suggest that one role of aqueous carbonic species CO2 could be to accelerate the adsorption of chloride ions and the formation of chloride intermediates.

The Impact of AI on Contact Resistance and Its Suitability in Fine Pitch Interconnects

Integration issues for a three-dimensional (3D) interconnect in a Face-to-Face (F2F) configuration are discussed. In particular, the effect of AI and organic dielectrics under the bump and their effect in chip-package-interaction (CPI) stresses as well as AI contact resistance issues that arise as the interconnection pitch is decreased. This paper will present a finite-element model created to study the stresses in advanced 3D microelectronic package. To assess the reliability of the 3D packages a submodeling approach is used to capture the CPI stresses. The modeling study presented indicates that it is beneficial to continue using AI pads as it has significatly lower stresses compared to copper pads/vias. In the second portion of the paper, the effect of PBO developer on AI corrosion is presented. Reactive ion etching (RIE) chemistries and wet chemistries were optimized using contact resistance as the success metric. Process robustness was achieved by decoupling the hard dielectric opening from the PBO via opening. Time of Flight Secondary Ion Mass Spectrometry (ToF-SIMS), Scanning Electron Microscopy (SEM), X-ray Photoelectron Spectroscopy (XPS) analysis were used to add clarity to the bump contact resistance values.