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Characterization of Tribofilm with the Remaining Lubricating Oil by Raman Spectroscopy
摘要： As a first step to develop a method of in situ analysis of tribological behavior under oil lubrication, surfaces after the tribo-test with the remaining lubricating oil were analyzed with Raman spectroscopy. A ball-on-disk type tribo-test using a S45C disk and a SUJ2 ball was performed, and then its friction track of the disk surface was analyzed by Raman spectroscopy. Polysulfide and mineral oil were used as the lubricating oil without dilution. In addition to each lubricant peak, iron disulfide (FeS2) tribofilm peaks were detected on the friction track in the case of polysulfide, whereas the magnetite (Fe3O4) peak was detected on the friction track in the case of mineral oil. FeS2 intensity increased overtime in the case of the test at 200°C. In this way, tribofilm and oxide were detected as the remaining lubricating oil by Raman spectroscopy, which therefore suggests that Raman spectroscopy is an effective analysis method to investigate the formation process of tribofilm and oxide under oil lubrication.
关键词： Raman spectroscopy,in situ,polysulfide,tribofilm,boundary lubrication
更新于2025-09-09 09:28:46
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[ACS Symposium Series] Raman Spectroscopy in the Undergraduate Curriculum Volume 1305 || Exploring the Figures of Merit of Surface-Enhanced Raman Spectroscopy
摘要： This undergraduate laboratory experiment is designed to help students gain a deeper understanding of surface-enhanced Raman spectroscopy (SERS). Students will learn to fabricate nanoparticles, obtain Raman and SERS data, construct calibration curves, and determine the signal-to-noise ratio, limit of detection, and coefficient of variation of alizarin, a dye molecule commonly found in cultural heritage materials. Overall, the laboratory experiment will provide an opportunity for students to develop laboratory skills in nanoscience and spectroscopy and further develop their critical thinking skills.
关键词： SERS,surface-enhanced Raman spectroscopy,limit of detection,calibration curves,alizarin,signal-to-noise ratio,nanoparticles,coefficient of variation
更新于2025-09-09 09:28:46
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[ACS Symposium Series] Raman Spectroscopy in the Undergraduate Curriculum Volume 1305 || Solvent Sensitivity of the ?C≡N Group: A Raman Spectroscopic Study
摘要： The cyano or nitrile group, ?C≡N, exhibits a distinct vibrational mode around the 2100–2300 cm-1 region that is highly sensitive to the solvent polarity, hydrogen bonding interactions, and the electric field around it. In this chapter, the solvent sensitivity of the ?C≡N group was studied using Raman spectroscopy. First, the Raman spectra of ?C≡N-containing samples ranging from acetonitrile to nitrile gloves were contrasted. Second, we give an example where the ?C≡N group had an associated pH dependence due to the groups around it. Lastly, we studied the effect of various solvents on the ?C≡N mode. Raman assignments were verified using DFT-based calculations.
关键词： cyano group,DFT calculations,Raman spectroscopy,nitrile group,solvent sensitivity
更新于2025-09-09 09:28:46
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Electrospray-Surface Enhanced Raman Spectroscopy (ES-SERS) for probing surface chemical compositions of atmospherically relevant particles
摘要： We present electrospray-surface enhanced Raman spectroscopy (ES-SERS) as a new approach to measuring the surface chemical compositions of atmospherically relevant particles. The surface-sensitive SERS is realized by electrospraying Ag nanoparticle aerosols over analyte particles. Spectral features at v(SO42-), v(C-H) and v(O-H) modes were observed from the normal Raman and SERS measurements of laboratory-generated supermicron particles of ammonium sulfate (AS), AS mixed with succinic acid (AS/SA) and AS mixed with sucrose (AS/sucrose). SERS measurements showed strong interaction (or chemisorption) between Ag nanoparticles and surface aqueous sulfate [SO42-] with [SO42-]AS/sucrose > [SO42-]AS/SA > [SO42-]AS. Enhanced spectra of the solid AS and AS/SA particles revealed the formation of surface-adsorbed water on their surfaces at 60% relative humidity. These observations of surface aqueous sulfate and adsorbed water demonstrate a possible role of surface-adsorbed water in facilitating the dissolution of sulfate from the bulk phase into its water layer(s). Submicron ambient aerosol particles collected in Hong Kong exhibited non-enhanced features of black carbon and enhanced features of sulfate and organic matter (carbonyl group), indicating an enrichment of sulfate and organic matter on the particle surface.
关键词： Electrospray-Surface Enhanced Raman Spectroscopy,succinic acid,atmospherically relevant particles,surface chemical compositions,ES-SERS,sucrose,Ag nanoparticles,surface-adsorbed water,organic matter,ammonium sulfate,black carbon
更新于2025-09-09 09:28:46
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Temperature-dependent Raman spectroscopic study of ferroelastic K <sub/>2</sub> Sr(MoO <sub/>4</sub> )
摘要： Raman scattering measurements of K2Sr(MoO4)2 were performed in the temperature range of 25–750 ?C. The Raman spectrum of the low-temperature phase α-K2Sr(MoO4)2 that was obtained by first-principle calculations indicated that the Raman bands in the wavenumber region of 250–500 cm?1 are related to Mo–O bending vibrations in MoO4 tetrahedra, while the Raman bands in the wavenumber region of 650–950 cm?1 are attributed to stretching vibrations of Mo–O bonds. The temperature-dependent Raman spectra reveal that K2Sr(MoO4)2 exhibits two sets of modifications in the Raman spectra at ～ 150 ?C and ～ 475 ?C, attributed to structural phase transitions. The large change of the Raman spectra in the temperature range of 150 ?C to 475 ?C suggests structural instability of the medium-temperature phase β -K2Sr(MoO4)2.
关键词： ferroelastics,K2Sr(MoO4)2 crystal,phase transition,Raman spectroscopy
更新于2025-09-09 09:28:46
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Direct nanocrystallite size investigation in microstrained mixed phase TiO2 nanoparticles by PCA of Raman spectra
摘要： Mixed phase anatase and rutile TiO2 nanoparticles (30-67 % R/A) have been synthesized by single step laser pyrolysis. Parallel studies by XRD and Raman spectroscopy suggested possible deforming microstress inside certain samples, due to boundary interactions between neighbouring nanocrystallites in nanoparticles, phase instabilities and/or O/C contents. Microstress in nanoparticles supports anatase phase stability in competition with rutile phase. Williamson-Hall plot was used to evaluate crystallite size and strain. A tensile global microstrain in anatase crystallites, was observed for elevated C content titania nanoparticles, together with compressive microstrain in crystallites within O deficient TiO2 nanoparticles. XPS and TEM characterization opens insights into the processes behind this type of behaviour. Principal Component Analysis of Raman spectra was applied for batch auto-characterization of mixed phase nanoparticles, with emphasis upon the method ability to simultaneously appreciate crystallite size for both anatase and rutile phase. The method focuses on covariational matrix of multiple samples Raman spectra. It provides results in good agreement with XRD calculated crystallite dimensions for unstrained titania, while for samples with microstrains it returns the size closer to the one predicted by Williamson-Hall plot.
关键词： Microstrain,Anatase,Principal Component Analysis (PCA),Raman Spectroscopy,Williamson-Hall,Rutile,TiO2 nanoparticles
更新于2025-09-09 09:28:46
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<i>In-Situ</i> Raman Measurements of Silicate Glasses during Vickers Indentation
摘要： In-situ structural changes of glass under a sharp diamond indenter are evaluated by using a micro-Raman spectrophotometer coupled with a self-made indentation equipment. This set-up enables us to obtain in-situ Raman spectra of glass under a Vickers indenter and to observe transient and permanent structural changes in glass. It is found that in-situ Raman spectra of silica glass under the Vickers indenter show distinct peak-broadening, which is not observed in the in-situ Raman spectra of hydrostatically compressed silica glass, nor in those of soda-lime silicate glass. This suggests that the indentation-induced shear stress causes the glass structure to be deformed into a di?erent one with a wider bond angle distribution. Such a shear-induced structural change could play a key role on the contact damage of glass, especially for glass with a high degree of polymerization, like silica glass.
关键词： indentation,Raman spectroscopy,glass
更新于2025-09-09 09:28:46
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[All]-S,S-dioxide Oligo-Thienylenevinylenes: Synthesis and Structural/Electronic Shapes From Their Molecular Force Fields
摘要： Oligo-S,S-dioxothienylenevinylenes have been prepared by transferring oxygens to the sulfur atoms using the HOF?CH3CN complex. Their photophysical properteis are presented in comparison with their thiophenevinylene congeners together with their vibrational properties and molecular force fields permiting the interpretation of the alteration of aromaticity and inter-ring exocyclic π-conjugation in this series.
关键词： force fields,Raman spectroscopy,electronic/structural features,sulfur dioxides,oligothienylene vinylene
更新于2025-09-09 09:28:46
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Pigment palette study of the XIX century plafond painting by Raman spectroscopy
摘要： Within the framework of the restoration painted plafond performed in the distemper technique at the first half of the 19th century were investigated by micro-Raman spectroscopy, UV photography, optical microscopy. One hundred and fifty artistic composition fragments samples were studied from the different parts of plafond. The presence of the following basic pigments: emerald green, Scheele’s green; ultramarine, indigo blue, azurites, vermilion, ferric oxide based pigments were observed. Lead white, calcite and gypsum were identified. It’s ownership of the author’s record is discussed. The places of pigments application in the author’s layer of painting were localized, basic and auxiliary materials were identified.
关键词： Raman spectroscopy,Pigments identification,Distemper,Wall painting
更新于2025-09-09 09:28:46
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Enhanced thermal conductivity of MoS2/InSe-nanoparticles/MoS2 hybrid sandwich structure
摘要： MoS2 based hybrid structures have much attention due to their novel structures and potential applications in diverse areas, such as solar energy conversion, thermoelectric power generation and photo-transistors. In the present work, we have fabricated a novel sandwich structure of MoS2/InSe-nano-particles (NPs)/MoS2 layers on SiO2/Si substrate by a combination of chemical vapor deposition and physical vapor deposition methods. The morphology of these structures was also studied using scanning electron microscopy. In addition, we have also explored the thermal properties of these hybrid sandwich structures using temperature and power-dependent Raman spectroscopy. For MoS2/InSe-NPs/MoS2 sample, the first-order temperature coefficients of E1 2g and A1g modes were found to be (cid:1)0.01722 (cid:1)1/K, respectively, which are significantly large compared to MoS2 layers without InSe- and (cid:1)0.01575 cm NPs (i.e. MoS2/MoS2 sample). Further, the thermal conductivity of MoS2/InSe-NPs/MoS2 and MoS2/MoS2 samples on SiO2/Si substrate was extracted as ~102.3 and ~81.7 W/m-K, respectively. This work suggests an effective way to form a novel 2D-MoS2 based sandwich structure with semiconductor/metal-NPs; opening up a new scenario to understand the electronic structure of the hybrid structure, and the local strain introduced by NPs. Electron-phonon interactions at an interface can have significant effects on electrical/thermal transport through the optoelectronic devices.
关键词： Hybrid sandwich structure,Thermal conductivity,Raman spectroscopy,Tensile-strain
更新于2025-09-09 09:28:46