Download or read book Electrochemical and In situ Surface enhanced Raman Spectroscopic SERS Study of Passive Films Formed on Low carbon Steel in Highly Alkaline Environments written by Mauricio Mancio and published by . This book was released on 2008 with total page 452 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Application of Surface Enhanced Raman Spectroscopy SERS to In situ Study of Passive Films on Iron and Steel in Aqueous Solutions written by Jing Gui and published by . This book was released on 1991 with total page 528 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book In situ Surface Enhanced Raman Spectroscopy Investigation of the Surface Films on Alloy 600 and Alloy 690 in Pressurized Water Reactor Primary Water written by Feng Wang and published by . This book was released on 2012 with total page 370 pages. Available in PDF, EPUB and Kindle. Book excerpt: Alloy 600 is found to be susceptible to stress corrosion cracking (SCC) in Pressurized Water Reactor (PWR) primary water environment. In this study, in-situ Surface Enhanced Raman Spectroscopy (SERS) is used to characterize surface films formed on Alloy 600 and Alloy 690 in PWR PW at 320oC. A simulated PWR PW system is constructed. In addition, a titanium autoclave is designed for high-temperature electrochemical tests. In this study, we have also measured SERS spectra of surface films formed on unalloyed nickel, unalloyed chromium, Ni-5Cr-8Fe, Ni-10Cr-8Fe, Ni-10Cr and Ni-20Cr. The surface films were formed at different potentials, from -0.9V to -0.5V vs SHE. A formation of NiO film is observed on the surface of nickel at -0.65V, which shows a Raman peak at 540 cm-1 due to crystal defects. For pure chromium, Cr2O3 passive film is formed on its surface. The Raman peaks are located at 540 cm-1 and 610 cm-1. The thickness of Cr2O3 passive film is about several nanometers, depending on the growth time in PWR PW. A peak at 610 cm-1 would likely indicate Cr2O3 and the absence of this peak, in conjunction with a peak at 540 cm-1, would indicate NiO. It is found that the surface films on Ni-5Cr-8Fe and Ni-10Cr-8Fe alloys are composed of Cr2O3 and FeCr2O4 spinel. No spinel oxide peak is observed in the SERS spectra for Ni-10Cr and Ni-20Cr binary alloys, and the surface film on both alloys is Cr2O3. An analysis of SERS spectra indicate that, as alloy's chromium concentration increases, the amount of Cr2O3 included in the alloy's surface film would increase. The surface film of Alloy 600 is composed of Cr2O3 inner layer (IL) and FeCr2O4 outer layer (OL). For short-time growth (10 min), the inner Cr2O3 layer is about 2 - 4 nm thick, and the average size of FeCr2O4 crystallites is about 10 nm. The actual film thickness depends on the growth time and aqueous environment. The surface film formed on Alloy 600 in PWR PW has a minor change if the sample is removed from the autoclave and exposed to air. The surface film of Alloy 690 is entirely a single layer of Cr2O3 (~ 2 nm thick). According to Diffusion Path Analysis, the difference on surface films formed on Alloy 600 and Alloy 690 is a consequence of a change in the relative diffusivity of O and Cr. Our in-situ SERS spectra measured for surface films on Alloy 600 and Alloy 690 are different with most of other people's findings. Three aspects have been considered and discussed. The first, there might be a difference between in-situ and ex-situ characterization techniques. The second, the film growth time in PWR PW is significantly different. The third, different autoclaves are used. The recirculating titanium autoclave is used in this study, while stainless steel autoclave is used in most of other studies, which might cause a change of the concentration of cations in the vicinity of metal surface and a precipitation of cations on the surface of oxides. It is found that the exposure time and testing autoclave might be responsible for the discrepancies between this study and the earlier studies. By using in-situ Surface Enhance Raman Spectroscopy (SERS), we have investigated the surface oxides formed on Alloy 600, Alloy 690, Ni-Cr, and Ni-Cr-Fe alloys in PWR primary water at 320oC. Our in-situ SERS spectra results suggest that SCC susceptibility of Ni-based alloys might be correlating with a formation of surface films formed in PWR primary water.
Download or read book The Application of Surface Enhanced Raman Spectroscopy to the In Situ Study of Passivity and Inhibition written by Lucy Jane Oblonsky and published by . This book was released on 1993 with total page 304 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Electronic Properties of Passive Films on Carbon Steel Rebar in Simulated Concrete Pore Solutions written by Jon William Williamson and published by . This book was released on 2015 with total page 235 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the highly alkaline environment of concrete, carbon steel rebar is protected against corrosion by a passive oxide/oxyhydroxide film. Understanding the characteristics of this passive film, and how it depassivates, is the key for mitigating problems associated with steel corrosion in concrete. Although a large number of electrochemical and analytical studies have been conducted on the passivity of steel in concrete, current mechanistic models do not explain all experimental observations about the chloride-induced depassivation process. One area that is not studied extensively is the electronic properties of semiconductive passive films such as those on steel rebar; a better understanding of these properties will provide additional information to improve the mechanistic models for chloride-induced depassivation of carbon steel in concrete. This research project used Mott-Schottky (M-S) analysis along with other electrochemical techniques to study the electronic properties of passive films that form on carbon steel exposed to simulated concrete pore solutions. Both passivation and chloride-induced depassivation processes were investigated, and changes in electronic properties during these processes were monitored. The main parameters of this study included the concrete pore solution composition, pH, and chloride amount. Challenges of using M-S analysis to study the electronic properties of passive films were also discussed. Results showed that the passive film on steel rebar is an n-type semiconductor with two discrete donor species. The space charge layer shows a thickness of around 0.4 nm at full passivation, a donor density on the order of 1021 cm−3, and a flatband potential between -0.5 to -0.6 V vs. saturated calomel reference electrode (SCE). Chloride concentrations above the chloride threshold resulted in loss of linearity of M-S plots, indicating a shift of the passive film from a crystalline to an amorphous structure. In addition to experimental investigations, numerical models used to describe the electronic properties of passive films were investigated, and an optimal numerical model for simulating the steel rebar passive film was identified.
Download or read book Raman Spectroscopy of Passive Films Formed on Metal Surfaces in Corrosive Environments written by R. Heidersbach and published by . This book was released on 1977 with total page 17 pages. Available in PDF, EPUB and Kindle. Book excerpt: In situ Raman spectra were obtained of passive films formed on metallic lead surfaces under freely corroding conditions in dilute hydrochloric acid and sodium hydroxide solutions. The spectra identified the coating formed in HCl solution as PbCl2 and that formed in NaOH solution as PbO. Passive film Composition was the same in solutions containing dissolved oxygen as in deoxygenated solutions but the rate of film growth was much greater in the presence of oxygen. Spectra of the films immersed in solution were virtually identical to those of the same films in air. The experimental program for passive films on lead was successfully completed. Investigations on passive films on iron surfaces were initiated. (Author).
Download or read book A Surface Enhanced Raman Spectroscopy SERS Study of Adsorption of Corrosion Inhibitors written by Ashish Agarwal and published by . This book was released on 2004 with total page 304 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Tip enhanced Raman Spectroscopy on Electrochemical Systems written by Thomas Touzalin and published by . This book was released on 2018 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The in situ investigation of electrochemical interfaces structures at the nanoscale is a key element in the understanding of charge and electron transfer mechanisms e.g. in the fields of energy storage or electrocatalysis. This thesis introduces the implementation of tip-enhanced Raman spectroscopy (TERS) in liquid and in electrochemical conditions enabling the nanoscale analysis of electrified solid/liquid interfaces through the strong and local electric field enhancement at gold or silver scanning tunneling microscopy (STM) probes. The ability of TERS to image inhomogeneities in the coverage density of a self-assembled monolayer (SAM) through a layer of organic solvent on gold was demonstrated. A TERS-inspired analytical tool was also developed, based on a TERS tip used simultaneously as a single-hot spot surface-enhanced Raman spectroscopy (SERS) platform and as a microelectrode (EC tip SERS). The reduction of an electroactive SAM could then be monitored by electrochemical and in situ SERS measurements. In situ electrochemical STM-TERS was also evidenced through the imaging of local variations of the electric field enhancement on peculiar sites of a gold electrode with a lateral resolution lower than 8 nm. Finally TERS also demonstrated to be efficient in investigating the structure of organic layers grafted either by electrochemical reduction or spontaneously. This work is therefore a major advance for the analysis of functionalized surfaces.
Download or read book Laser Raman Spectroscopy in Studies of Corrosion and Electrocatalysis written by and published by . This book was released on 1988 with total page 43 pages. Available in PDF, EPUB and Kindle. Book excerpt: Laser Raman Spectroscopy (LRS) has become an important tool for the in-situ structural study of electrochemical systems and processes in recent years. Following a brief introduction of the experimental techniques involved in applying LRS to electrochemical systems, we survey the literature for examples of studies in the inhibition of electrode reactions by surface films (e.g., corrosion and passivation phenomena) as well as the acceleration of reactions by electro-sorbates (electrocatalysis). We deal mostly with both normal and resonance Raman effects on fairly thick surface films in contrast to surface-enhanced Raman investigations of monolayer adsorbates, which is covered in another lecture. Laser Raman spectroelectrochemical studies of corrosion and film formation on such metals as Pb, Ag, Fe, Ni, Co, Cr, Au, stainless steel, etc. in various solution conditions are discussed. Further extension of the technique to studies in high-temperature and high-pressure aqueous environments is demonstrated. Results of studies of the structure of corrosion inhibitors are also presented. As applications of the LRS technique in the area of electrocatalysis, we cite studies of the structure of transition metal macrocyclic compounds, i.e., phthalocyanines and porphyrins, used for catalysis of the oxygen reduction reaction. 104 refs., 20 figs.
Download or read book Metals Abstracts written by and published by . This book was released on 1989 with total page 1558 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Modifications of Passive Films written by P. Marcus and published by CRC Press. This book was released on 2023-06-09 with total page 360 pages. Available in PDF, EPUB and Kindle. Book excerpt: The modification of passive films is a promising method of improving the corrosion resistance of metallic materials. As well as reviewing a wide spectrum of film modifications and their effects on passivity and to corrosion resistance, papers presented at this international symposium deal with chemical composition, chemical states and electronic properties of passive films.
Download or read book Applications of Raman Spectroscopy in Cu CMP and in BEOL Cleaning Chemistries written by Siddartha Kondoju and published by . This book was released on 2007 with total page 320 pages. Available in PDF, EPUB and Kindle. Book excerpt: In copper chemical mechanical planarization (CMP), in situ detection of barrier to dielectric layer transition is typically done using an optical reflectance technique. The introduction of carbon doped oxides (CDOs) as low-dielectric constant (k) materials for dielectric layers has opened up the possibility of using spectroscopic techniques for detecting such transitions more efficiently. The vibrational frequencies of the bonds between C, H, O, and Si in these low-k materials may be readily detected by spectroscopic techniques such as Raman and infrared (IR) spectroscopies. Since CMP is carried out in aqueous media, IR spectroscopy is not very desirable due to strong absorption of water in the same region as C-H vibrations (2800 cm-1 to 3300 cm-1). In contrast, Raman spectroscopy shows minimal water interference and can be used to efficiently monitor the signal from CDO films even in aqueous environments that prevail under CMP conditions. The research reported in this dissertation concerns the use of Raman spectroscopy in detecting the transition from tantalum (Ta) barrier layer to CDO dielectric layer, in-situ. Intensities of Raman peaks characteristic of Si-Si vibrations from silicon substrates and C-H vibrations from low-k materials were used for monitoring CDO thickness and detecting removal of Ta layer. An abrasion cell was integrated with a Raman spectrometer to demonstrate the feasibility of Raman monitoring in-situ. Additionally, an alternative method was investigated for monitoring transitions in highly fluorescent low-k materials where Raman can not be used. The fluorescence intensity was used to effectively monitor Ta to low-k transitions. As a secondary objective, the Raman technique was used to monitor the composition of polishing slurries, which in the case of copper CMP, have a rich chemistry, which may change during the course of polishing due to consumption and decomposition of certain constituents. Various aspects, such as small layer thickness (50μm), continuous flow of the slurry, and dynamics of the film removal process pose a great challenge to the monitoring of slurry components between the pad and the wafer. The slurry constituents such as oxidants and corrosion inhibitors have unique signatures that can be detected using spectroscopic techniques. In this study Raman spectroscopy was used to detect and quantify chemical species such as hydroxylamine, benzotriazole and hydrogen peroxide in-situ. A more detailed study pertaining to the protonation of hydroxylamine with respect to the pH was also performed. Finally, surface enhanced Raman spectroscopy (SERS) was also investigated to improve the detection of pyridine and benzotriazole at low concentrations (100ppm).
Download or read book Characterization and Optimization of Novel Nanostructured Metallic Substrates for Surface Enhanced Raman Spectroscopy written by and published by . This book was released on 2001 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Surface enhanced Raman spectroscopy (SERS) is a highly sensitive technique for quantifying trace amounts of analyte adsorbed at a roughened metal surface. We have shown that novel gold nanostructured films, simply fabricated using gold nanoparticles and latex microspheres, can be used as highly sensitive SERS substrates. The films are templated by layers of colloidal crystals and display long ranged ordered regions, and porosity on two length scales that results in high surface area. By integrating these substrates into a flow chamber we have obtained consistent reproducible data and demonstrated the quantitative detection of sodium cyanide in the concentration range from 5 to 500 ppb, with detection significantly enhanced by lowering the pH after cyanide adsorption. We have found that the optimum size of the latex microspheres is approximately equal to the wavelength of the laser. Finally, the SERS activity of the gold substrates coated with silver nanoparticles was investigated using methyl phosphonic acid (MPA). Detection of MPA was dependent on the time between substrate coating and the SERS measurement. These studies show that novel materials formed by simple wet chemistry techniques can be used efficiently in practical devices for the detection of chemical agents.
Download or read book Ultrahigh vacuum Studies of Surface Enhanced Raman Scattering from Absorbates on Modulated Silver Surfaces written by Pia Naoko Sanda and published by . This book was released on 1982 with total page 300 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Ex situ and In situ Spectroscopic Studies of the Passive Film on Alkali and Alkaline Earth Metals in Nonaqueous Solvents Final Report written by and published by . This book was released on 1992 with total page 44 pages. Available in PDF, EPUB and Kindle. Book excerpt: The adsorption of carbon dioxide on potassium-dosed Ag(111) has been investigated with temperature-programmed desorption (TPD), work function measurements, and Auger electron (AES), X-ray photoelectron (XPS), and high resolution electron energy loss (HREELS), spectroscopies. Unlike the behavior observed for other K-modified single-crystal metal surfaces, the TPD spectra of near-saturation coverages of CO2 on K/Ag(111) for K coverages in the range 0.13
Download or read book Use of Surface Enhanced Raman Spectroscopy SERS in the Study of Corrosion Inhibition and Passivation Processes on Copper and Copper Base Alloys written by B. H. Loo and published by . This book was released on 1892 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Surface Enhanced Raman Spectroscopy of Functionalized Self assembled Monolayers written by Qi Ye and published by . This book was released on 1997 with total page 616 pages. Available in PDF, EPUB and Kindle. Book excerpt:
