Photoswitching tripodal single molecular tip for noncontact AFM measurements: synthesis, immobilization, and reversible configurational change on gold surface

2010 ◽  
Vol 8 (16) ◽  
pp. 3655 ◽  
Author(s):  
Daiko Takamatsu ◽  
Ken-ichi Fukui ◽  
Safwan Aroua ◽  
Yoko Yamakoshi
Keyword(s):  
Gold Surface ◽  
Configurational Change ◽  
Noncontact Afm

Materials Characterization of Lead Free Compositions for Minimum Temperature SMT Processes at the SLI-Second Level Interconnect Solder Joint

2004 ◽  
Author(s):  
Norman J. Armendariz ◽  
Prawin Paulraj
Keyword(s):  
Solder Joint ◽  
Printed Circuit Board ◽  
Gold Surface ◽  
Circuit Board ◽  
Lead Free ◽  
Processing Temperature ◽  
The European Union ◽  
Printed Circuit ◽  
Higher Temperature ◽  
Tin Silver Copper

Abstract The European Union is banning the use of Pb in electronic products starting July 1st, 2006. Printed circuit board assemblies or “motherboards” require that planned CPU sockets and BGA chipsets use lead-free solder ball compositions at the second level interconnections (SLI) to attach to a printed circuit board (PCB) and survive various assembly and reliability test conditions for end-use deployment. Intel is pro-actively preparing for this anticipated Pb ban, by evaluating a new lead free (LF) solder alloy in the ternary Tin- Silver-Copper (Sn4.0Ag0.5Cu) system and developing higher temperature board assembly processes. This will be pursued with a focus on achieving the lowest process temperature required to avoid deleterious higher temperature effects and still achieve a metallurgically compatible solder joint. One primary factor is the elevated peak reflow temperature required for surface mount technology (SMT) LF assembly, which is approximately 250 °C compared to present eutectic tin/lead (Sn37Pb) reflow temperatures of around 220 °C. In addition, extended SMT time-above-liquidus (TAL) and subsequent cooling rates are also a concern not only for the critical BGA chipsets and CPU BGA sockets but to other components similarly attached to the same PCB substrate. PCBs used were conventional FR-4 substrates with organic solder preservative on the copper pads and mechanical daisychanged FCBGA components with direct immersion gold surface finish on their copper pads. However, a materials analysis method and approach is also required to characterize and evaluate the effect of low peak temperature LF SMT processing on the PBA SLI to identify the absolute limits or “cliffs” and determine if the minimum processing temperature and TAL could be further lowered. The SLI system is characterized using various microanalytical techniques, such as, conventional optical microscopy, scanning electron microscopy, energy dispersive spectroscopy and microhardness testing. In addition, the SLI is further characterized using macroanalytical techniques such as dye penetrant testing (DPT) with controlled tensile testing for mechanical strength in addition to disbond and crack area mapping to complete the analysis.

A Comparative Study of Adsorption of Aliphatic Amines at a Gold Electrode

2005 ◽  
Vol 70 (12) ◽  
pp. 2027-2037 ◽  
Author(s):  
Teresa Łuczak
Keyword(s):  
Gibbs Energy ◽  
Comparative Study ◽  
Gold Electrode ◽  
Surface Coverage ◽  
Standard Gibbs Energy ◽  
Gold Surface ◽  
Experimental Dependence ◽  
Aliphatic Amines ◽  
Solvent Interactions ◽  
Amine Concentration

Adsorption of aliphatic amines (C1-C4) at the gold electrode was studied by tensammetry. It has been established that the experimental dependence between the gold surface coverage (Θ) and the bulk amine concentration (cA) fits satisfactorily both by the Frumkin and Flory-Huggins isotherms. The standard Gibbs energy of adsorption, ∆G°ad at Emax for Θ < 0.8 has been found to increase in the order methylamine < ethylamine < propylamine < butylamine. This is rationalised in terms of surface-adsorbate, adsorbate-adsorbate and adsorbate-solvent interactions.

scholarly journals On-surface activation of benzylic C-H bonds for the synthesis of pentagon-fused graphene nanoribbons

Nano Research ◽  
2021 ◽  
Author(s):  
Xiushang Xu ◽  
Marco Di Giovannantonio ◽  
José I. Urgel ◽  
Carlo A. Pignedoli ◽  
Pascal Ruffieux ◽  
...  
Keyword(s):  
Carbon Nanomaterials ◽  
Graphene Nanoribbons ◽  
Gold Surface ◽  
Fine Tuning ◽  
Uniform Structure ◽  
Methyl Groups ◽  
Structural Modifications ◽  
Force Microscopy ◽  
Chemical Structures ◽  
Atomic Force

AbstractGraphene nanoribbons (GNRs) have potential for applications in electronic devices. A key issue, thereby, is the fine-tuning of their electronic characteristics, which can be achieved through subtle structural modifications. These are not limited to the conventional armchair, zigzag, and cove edges, but also possible through incorporation of non-hexagonal rings. On-surface synthesis enables the fabrication and visualization of GNRs with atomically precise chemical structures, but strategies for the incorporation of non-hexagonal rings have been underexplored. Herein, we describe the on-surface synthesis of armchair-edged GNRs with incorporated five-membered rings through the C-H activation and cyclization of benzylic methyl groups. Ortho-Tolyl-substituted dibromobianthryl was employed as the precursor monomer, and visualization of the resulting structures after annealing at 300 °C on a gold surface by high-resolution noncontact atomic force microscopy clearly revealed the formation of methylene-bridged pentagons at the GNR edges. These persisted after annealing at 340 °C, along with a few fully conjugated pentagons having singly-hydrogenated apexes. The benzylic methyl groups could also migrate or cleave-off, resulting in defects lacking the five-membered rings. Moreover, unexpected and unique structural rearrangements, including the formation of embedded heptagons, were observed. Despite the coexistence of different reaction pathways that hamper selective synthesis of a uniform structure, our results provide novel insights into on-surface reactions en route to functional, non-benzenoid carbon nanomaterials.

scholarly journals Quantitative Assessment of Periodontal Bacteria Using a Cell-Based Immunoassay with Functionalized Quartz Crystal Microbalance

Chemosensors ◽  
2021 ◽  
Vol 9 (7) ◽  
pp. 159
Author(s):  
Satit Rodphukdeekul ◽  
Miyuki Tabata ◽  
Chindanai Ratanaporncharoen ◽  
Yasuo Takeuchi ◽  
Pakpum Somboon ◽  
...  
Keyword(s):  
Monoclonal Antibody ◽  
Quartz Crystal Microbalance ◽  
Quantitative Assessment ◽  
Quartz Crystal ◽  
Dynamic Range ◽  
Gold Surface ◽  
Enzyme Linked Immunosorbent Assay ◽  
Inflammatory Disorder ◽  
Label Free ◽  
Periodontal Bacteria

Periodontal disease is an inflammatory disorder that is triggered by bacterial plaque and causes the destruction of the tooth-supporting tissues leading to tooth loss. Several bacteria species, including Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans, are considered to be associated with severe periodontal conditions. In this study, we demonstrated a quartz crystal microbalance (QCM) immunoassay for quantitative assessment of the periodontal bacteria, A. actinomycetemcomitans. An immunosensor was constructed using a self-assembled monolayer of 11-mercaptoundecanoic acid (11-MUA) on the gold surface of a QCM chip. The 11-MUA layer was evaluated using a cyclic voltammetry technique to determine its mass and packing density. Next, a monoclonal antibody was covalently linked to 11-MUA using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide/N-hydroxysuccinimide to act as the biorecognition element. The specificity of the monoclonal antibody was confirmed by an enzyme-linked immunosorbent assay. A calibration curve, for the relationship between the frequency shifts and number of bacteria, was used to calculate the number of A. actinomycetemcomitans bacteria in a test sample. Based on a regression equation, the lower detection limit was 800 cells, with a dynamic range up to 2.32 × 106 cells. Thus, the QCM biosensor in this study provides a sensitive and label-free method for quantitative analysis of periodontal bacteria. The method can be used in various biosensing assays for practical application and routine detection of periodontitis pathogens.

scholarly journals Molecular bridge-mediated ultralow-power gas sensing

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Aishwaryadev Banerjee ◽  
Shakir-Ul Haque Khan ◽  
Samuel Broadbent ◽  
Ashrafuzzaman Bulbul ◽  
Kyeong Heon Kim ◽  
...  
Keyword(s):  
Gas Sensing ◽  
Electron Tunneling ◽  
Gold Surface ◽  
Gold Electrodes ◽  
Self Assembled Monolayer ◽  
Output Resistance ◽  
Resistance Change ◽  
Ultralow Power ◽  
Linker Molecules ◽  
Molecular Bridge

AbstractWe report the electrical detection of captured gases through measurement of the quantum tunneling characteristics of gas-mediated molecular junctions formed across nanogaps. The gas-sensing nanogap device consists of a pair of vertically stacked gold electrodes separated by an insulating 6 nm spacer (~1.5 nm of sputtered α-Si and ~4.5 nm ALD SiO2), which is notched ~10 nm into the stack between the gold electrodes. The exposed gold surface is functionalized with a self-assembled monolayer (SAM) of conjugated thiol linker molecules. When the device is exposed to a target gas (1,5-diaminopentane), the SAM layer electrostatically captures the target gas molecules, forming a molecular bridge across the nanogap. The gas capture lowers the barrier potential for electron tunneling across the notched edge region, from ~5 eV to ~0.9 eV and establishes additional conducting paths for charge transport between the gold electrodes, leading to a substantial decrease in junction resistance. We demonstrated an output resistance change of >108 times upon exposure to 80 ppm diamine target gas as well as ultralow standby power consumption of <15 pW, confirming electron tunneling through molecular bridges for ultralow-power gas sensing.

scholarly journals Au(100) as a Template for Pentacene Monolayer

Molecules ◽  
2021 ◽  
Vol 26 (8) ◽  
pp. 2393
Author(s):  
Artur Trembułowicz ◽  
Agata Sabik ◽  
Miłosz Grodzicki
Keyword(s):  
Self Assembly ◽  
Molecular Layer ◽  
High Vacuum ◽  
Gold Surface ◽  
Ultra High Vacuum ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Height Difference ◽  
Characteristic Features ◽  
Reconstructed Surface

The surface of quasi-hexagonal reconstructed Au(100) is used as the template for monolayer pentacene (PEN) self-assembly. The system is characterized by means of scanning tunneling microscopy at room temperature and under an ultra-high vacuum. A new modulated pattern of molecules with long molecular axes (MA) arranged along hex stripes is found. The characteristic features of the hex reconstruction are preserved herein. The assembly with MA across the hex rows leads to an unmodulated structure, where the molecular layer does not recreate the buckled hex phase. The presence of the molecules partly lifts the reconstruction—i.e., the gold hex phase is transformed into a (1×1) phase. The arrangement of PEN on the gold (1×1) structure is the same as that of the surrounding molecular domain on the reconstructed surface. The apparent height difference between phases allows for the distinction of the state of the underlying gold surface.

scholarly journals Tuning the Covering on Gold Surfaces by Grafting Amino-Aryl Films Functionalized with Fe(II) Phthalocyanine: Performance on the Electrocatalysis of Oxygen Reduction

Molecules ◽  
2021 ◽  
Vol 26 (6) ◽  
pp. 1631
Author(s):  
Camila F. Olguín ◽  
Nicolás Agurto ◽  
Carlos P. Silva ◽  
Carolina P. Candia ◽  
Mireya Santander-Nelli ◽  
...  
Keyword(s):  
Oxygen Reduction ◽  
Diazonium Salt ◽  
Gold Surface ◽  
Catalytic Performance ◽  
Reduction Reaction ◽  
Salt Reduction ◽  
Surface Electrodes ◽  
Custom Made ◽  
Aryl Diazonium Salt ◽  
Inorganic Molecules

Current selective modification methods, coupled with functionalization through organic or inorganic molecules, are crucial for designing and constructing custom-made molecular materials that act as electroactive interfaces. A versatile method for derivatizing surfaces is through an aryl diazonium salt reduction reaction (DSRR). A prominent feature of this strategy is that it can be carried out on various materials. Using the DSRR, we modified gold surface electrodes with 4-aminebenzene from 4-nitrobenzenediazonium tetrafluoroborate (NBTF), regulating the deposited mass of the aryl film to achieve covering control on the electrode surface. We got different degrees of covering: monolayer, intermediate, and multilayer. Afterwards, the ArNO2 end groups were electrochemically reduced to ArNH2 and functionalized with Fe(II)-Phthalocyanine to study the catalytic performance for the oxygen reduction reaction (ORR). The thickness of the electrode covering determines its response in front of ORR. Interestingly, the experimental results showed that an intermediate covering film presents a better electrocatalytic response for ORR, driving the reaction by a four-electron pathway.

scholarly journals Formation of HCN+ in collisions of N+ and N2+ with a self-assembled propanethiol surface on gold

2021 ◽  
Author(s):  
Faro Hechenberger ◽  
Siegfried Kollotzek ◽  
Lorenz Ballauf ◽  
Felix Duensing ◽  
Milan Ončák ◽  
...  
Keyword(s):  
Energy Range ◽  
Incident Energy ◽  
Gold Surface ◽  
Self Assembled Monolayer ◽  
Polycrystalline Gold ◽  
Self Assembled

Collisions of N+ and N2+ with C3 hydrocarbons, represented by a self assembled monolayer of propanethiol on a polycrystalline gold surface, were investigated by experiments over the incident energy range between 5 eV and 100 eV.

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