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Study of the phase composition and tribological properties of carbon tool steels after laser surface hardening by quasi - CW fiber laser
摘要： The paper contains the investigation results on the structure and phase composition of the laser radiation area (LRA) of the U8 and U10 steels over its entire thickness. In the present study, the laser surface hardening of both U8 (ASTM - W1-7) and U10 (ASTM - W1-9) steels in the air was performed by exploiting a quasi - CW fiber laser with a 130 W power and 3 mm/s processing speed. The phase composition of the oxide layer formed as a result of laser treatment (LT) in air, as well as the structure of the oxide-metal interface on the surface of U8 (ASTM–W1-7) and U10 (ASTM–W1-9) carbon tool steels were studied by X-ray photoelectron spectroscopy (XPS). It was established that the thickness of the completely oxidized surface layers for U8 and U10 steels is 38.7 nm and 99 nm, respectively. The composition of the oxides of the steel surface after LT was determined. The presence of a wüstite-based film on U8 steel evidences the low wear properties of the LRA surface, while the thicker oxide layer of the modified U10 steel which contains Fe2O3 and Fe3O4 oxides with better strength properties, on the contrary, provides U10 steel surface with higher wear resistance. It was found that the wear rate of U10 steel modified surface decreases by more than two times, while the given value for U8 steel reduces no more than 17%. The paper reports the metallographic examination of the LRA structure. It was shown that the wear-resistant structural components that appeared after laser treatment lead to an increase in the deformation properties of steels. The maximum microhardness value of the LRA is 710 HV0.1 for U8 steel and 750 HV0.1for U10 steel.
关键词： Laser radiation,Oxidized surface layers,X-ray photoelectron spectroscopy,Phase composition,Surface finishing treatment,Elemental composition
更新于2025-09-19 17:13:59
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Sol-Gel Processed TiO2 Nanotube Photoelectrodes for Dye-Sensitized Solar Cells with Enhanced Photovoltaic Performance
摘要： The performance of dye-sensitized solar cells (DSCs) critically depends on the efficiency of electron transport within the TiO2-dye-electrolyte interface. To improve the efficiency of the electron transfer the conventional structure of the working electrode (WE) based on TiO2 nanoparticles (NPs) was replaced with TiO2 nanotubes (NTs). Sol-gel method was used to prepare undoped and Nb-doped TiO2 NPs and TiO2 NTs. The crystallinity and morphology of the WEs were characterized using XRD, SEM and TEM techniques. XPS and PL measurements revealed a higher concentration of oxygen-related defects at the surface of NPs-based electrodes compared to that based on NTs. Replacement of the conventional NPs-based TiO2 WE with alternative led to a 15% increase in power conversion efficiency (PCE) of the DSCs. The effect is attributed to the more efficient transfer of charge carriers in the NTs-based electrodes due to lower defect concentration. The suggestion was confirmed experimentally by electrical impedance spectroscopy measurements when we observed the higher recombination resistance at the TiO2 NTs-electrolyte interface compared to that at the TiO2 NPs-electrolyte interface. Moreover, Nb-doping of the TiO2 structures yields an additional 14% PCE increase. The application of Nb-doped TiO2 NTs as photo-electrode enables the fabrication of a DSC with an efficiency of 8.1%, which is 35% higher than that of a cell using a TiO2 NPs. Finally, NTs-based DSCs have demonstrated a 65% increase in the PCE value, when light intensity was decreased from 1000 to 10 W/m2 making such kind device be promising alternative indoor PV applications when the intensity of incident light is low.
关键词： nanotubes,X-ray photoelectron spectroscopy,dye-sensitized solar cells,semiconductor-liquid interface,charge traps
更新于2025-09-19 17:13:59
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High-resolution photoelectron imaging and resonant photoelectron spectroscopy <i>via</i> noncovalently bound excited states of cryogenically cooled anions
摘要： Valence-bound anions with polar neutral cores (m > (cid:1)2.5 D) can support dipole-bound excited states below the detachment threshold. These dipole-bound states (DBSs) are highly di?use and the weakly bound electron in the DBS can be readily autodetached via vibronic coupling. Excited DBSs can be observed in photodetachment spectroscopy using a tunable laser. Tuning the detachment laser to above-threshold vibrational resonances yields vibrationally enhanced resonant photoelectron spectra, which are highly non-Franck–Condon with much richer vibrational information. This perspective describes recent advances in the studies of excited DBSs of cryogenically cooled anions using high-resolution photoelectron imaging (PEI) and resonant photoelectron spectroscopy (rPES). The basic features of dipole-bound excited states and highly non-Franck–Condon resonant photoelectron spectra will be discussed. The power of rPES to yield rich vibrational information beyond conventional PES will be highlighted, especially for low-frequency and Franck–Condon-inactive vibrational modes, which are otherwise not accessible from non-resonant conventional PES. Mode-selectivity and intra-molecular rescattering have been observed during the vibrationally induced autodetachment. Conformer-speci?c rPES is possible due to the di?erent dipole-bound excited states of molecular conformers with polar neutral cores. For molecules with m (cid:3) 2.5 D or without dipole moments, but large quadrupole moments, excited quadrupole-bound states can exist, which can also be used to conduct rPES.
关键词： photoelectron imaging,resonant photoelectron spectroscopy,dipole-bound states,vibrational autodetachment,cryogenically cooled anions
更新于2025-09-16 10:30:52
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SPR responsive xylenol orange functionalized gold nanoparticles- optical sensor for estimation of Al3+ in water
摘要： Xylenol orange functionalized gold nanoparticles (XO-AuNPs), prepared by reducing HAuCl4 in presence of xylenol orange were found to be selective and sensitive for optical sensing of Al3+ in water. XO-AuNPs nanoparticles were characterized by transmission electron microscopy (TEM), x-ray diffraction (XRD) and x-ray photoelectron spectroscopy (XPS); the nanoparticles formed were of spherical shape and of uniform size of 3-12 nm. The interaction between Al3+ and XO-AuNPs at pH ~3 was studied by XPS analysis. XPS and TEM studies revealed that aggregation of XO-AuNPs in the presence of Al3+ takes place through analyte induced cross-linkage mechanism. Al3+ induced selective aggregation of the XO-AuNPs lead to a visual change in color of the colloidal solution from deep red to blue. The changes in characteristic absorption peak of XO-AuNPs were monitored; the ratio of A550nm/A515nm was used to quantify the concentration of Al3+ in water samples. The method gave a linear response from 50?300 ppb (R2 = 0.985) of Al3+ in drinking water with a detection limit of 12 ppb. The proposed method did not suffer any major interference from concomitant transition metal ions and anions. The developed method was simple, rapid and useful for determination of Al3+ in drinking water samples.
关键词： Aluminium,UV-visible spectroscopy,Optical sensor,Gold nanoparticles,X-ray photoelectron spectroscopy,Xylenol orange
更新于2025-09-16 10:30:52
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Investigation on Surface Properties of Mn-Doped CdSe Quantum Dots Studied by X-ray Photoelectron Spectroscopy
摘要： In this work, we report on the effects of incorporating manganese (Mn) dopant into different sizes of cadmium selenide (CdSe) quantum dots (QDs), which improves the electronic and optical properties of the QDs for multiple applications such as light-emitting diodes, lasers, and biological labels. Furthermore, the greener inverse Micelle method was implemented using organic ligand, which is oleic acid. This binding of the surface enhanced the QDs’ surface trap passivation of Mn-doped CdSe, which then increased the quantity of the output. In addition, the inverse Micelle technique was used successfully to dope Mn into CdSe QDs without the risk of Mn dopants being self-purified as experienced by wurtzite CdSe QDs. Also, we report the X-ray photoelectron spectroscopy (XPS) results and analysis of zinc blended manganese-doped cadmium selenide quantum dots (Mn-doped CdSe QDs), which were synthesized with physical sizes that varied from 3 to 14 nm using the inverse Micelle method. The XPS scans traced the existence of the Se 3d and Cd 3d band of CdSe crystals with a 54.1 and 404.5 eV binding energy. The traced 640.7 eV XPS peak is proof that Mn was integrated into the lattice of CdSe QDs. The binding energy of the QDs was related to the increase in the size of the QDs.
关键词： quantum dots,semiconductor,chemical synthesis,cadmium selenide,X-ray photoelectron spectroscopy,manganese doped
更新于2025-09-16 10:30:52
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Influence of Surface Ligands on Energetics at FASnI <sub/>3</sub> /C <sub/>60</sub> Interfaces and Their Impact on Photovoltaic Performance
摘要： Interfacial chemistry and energetics significantly impact the performance of photovoltaic devices. In the case of Pb-containing organic metal halide perovskites, photoelectron spectroscopy has been used to determine the energetic alignment of frontier electronic energy levels at various interfaces present in the photovoltaic device. For the Sn-containing analogues, which are less toxic, no such measurements have been made. Through a combination of inverse, and X-ray photoelectron spectroscopy ultraviolet, (UPS, IPES, and XPS, respectively) measurements taken at varying thickness increments during stepwise deposition of C60 on FASnI3, we present the first direct measurements of the frontier electronic energy levels across the FASnI3/C60 interface. The results show band bending in both materials and transport gap widening in FASnI3 at the interface with C60. The XPS results show that iodide diffuses into C60 and results in n-doping of C60. This iodide diffusion out of FASnI3 impacts the valence and conduction band energies of FASnI3 more than the core levels, with the core level shifts displaying a different trend than the valence and conduction bands. Surface treatment of FASnI3 with carboxylic acids and bulky ammonium substituted surface ligands results in slight alterations in the interfacial energetics, and all surface ligands result in similar or improved PV performance relative to the untreated devices. The greatest PV stability results from treatment with a fluorinated carboxylic acid derivative; however, iodide diffusion is still observed to occur with this surface ligand.
关键词： perovskite solar cell,formamidinium tin iodide,interfacial energetics,inverse photoelectron spectroscopy,surface modification,photoelectron spectroscopy,ion diffusion
更新于2025-09-12 10:27:22
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Overcoming consistency constrains of ITO/ZnO/P3HT:PCBM/Ag solar cell by open air annealing and its systematic stability study under inborn conditions
摘要： Focusing on simplicity and industrial viability, polymer solar cells with configuration indium tin oxide (ITO)/ZnO/P3HT:PCBM/Ag were fabricated and characterized. Differing from the usual trend of using glove box for polymer device fabrication, here electron transport and active layer of the devices were deposited and stored in open air atmosphere without any encapsulation. Effect of active layer thickness on device performance was analyzed. Choosing the optimum thickness of 220 ± 20 nm, a number of devices were fabricated with same configuration and the effect of annealing on the photovoltaic parameters was investigated. Unlike annealing studies reported in literature, particular emphasis was given here to study the influence of annealing in ambient atmosphere, at temperature of 50 °C, for 30 s. This short period, low temperature annealing enhanced the device parameters mainly short circuit current density and hence efficiency. Lifetime measurements were done by monitoring the device and measuring its J–V parameters periodically for 1 year. X-ray photoelectron spectroscopy depth profile analysis was employed to demonstrate that surface modified ZnO effectively hinders the diffusion of indium from ITO to active layer.
关键词： Stability study,ITO/ZnO/P3HT:PCBM/Ag,X-ray photoelectron spectroscopy,Polymer solar cells,Open air annealing
更新于2025-09-12 10:27:22
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Local valence electronic states of silicon (sub)oxides on HfO2/Si-(sub)oxide/Si(110) and HfSi2/Si-(sub)oxide/Si(110) Islands
摘要： The effect on the local valence electronic states of Sin+ suboxide components (n = 2, 3, and 4) of hafnium deposited on a low-index Si(110) substrate is investigated by Si-L23VV Auger electron Sin+-2p photoelectron coincidence spectroscopy (Si-L23VV-Sin+-2p APECS), and the chemical states and stabilities are discussed. Hafnium-covered Si(110) is immediately oxidized to HfO2 and SiO2 because hafnium serves as an effective catalyst for Si oxidation. Therefore, a HfO2/Sin+-(sub)oxide/Si(110) [HfO2/Sin+/Si(110)] structure is easily formed (n = 1, 2, 3, and 4). Oxygen diffusion from HfO2 layers toward the Si(110) substrate is promoted by annealing at 923 K. Oxygen atom desorption from the HfO2/Sin+/Si(110) surface occurs after annealing at 1073 K, and HfSi2 islands (i-HfSi2) are formed with a partly exposed Si(110)-16 × 2 double domain (DD) surface. i-HfSi2 shows low reactivity toward O2 molecules, whereas the exposed Si(110)-16 × 2 DD surface is immediately oxidized. Here, a i-HfSi2/Sin+-(sub)oxide/Si(110) structure is formed. Furthermore, we measure the Si-L23VV-Sin+-2p APECS spectra of Sin+ in the HfO2/Sin+/Si(110) and the i-HfSi2/Sin+/Si(110) structures (n = 2, 3, and 4) to evaluate the local valence electronic states of the Sin+ (sub)oxide components. The binding energy at the valence band maximum (BEVBM) of Sin+ in the i-HfSi2/Sin+/Si(110) structure is lower than 1.5 ± 0.7 eV as compared to that in the HfO2/Sin+/Si(110) structure (n = 2, 3, and 4). The local valence electric states of the nearest neighbors and the second neighbors through oxygen of Sin+ are determined to affect those of the Sin+ atom (n = 2, 3, and 4). The Sin+ atoms in the i-HfSi2/Sin+/Si(110) structure can directly bond to hafnium atoms as the nearest neighbors and most commonly have Sim+ atoms in lower ionic valence states as second neighbors (m < 4), whereas the Sin+ atoms in the HfO2/Sin+/Si(110) structure cannot form this bond. In addition, the existence of Hf silicide and Si in lower ionic valence states can reduce the band gap of the HfO2/Si(110) structure.
关键词： High-dielectric-constant material,X-ray photoelectron spectroscopy,Local valence electronic states at surface and interface,Synchrotron radiation,Auger photoelectron coincidence spectroscopy,Metal-insulator-semiconductor structure
更新于2025-09-11 14:15:04
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Characterization of the Electronic Properties of Single‐Walled Carbon Nanotubes Filled with an Electron Donor—Rubidium Iodide: Multifrequency Raman and X‐ray Photoelectron Spectroscopy Studies
摘要： Single-walled carbon nanotubes (SWCNTs) with a mean diameter of 1.4 nm are filled with rubidium iodide. The filling of nanotubes is proved by high-resolution scanning transmission electron microscopy. The chemical composition of the filler is confirmed by X-ray photoelectron spectroscopy (XPS). The electronic properties of the filled SWCNTs are studied by XPS and Raman spectroscopy. The encapsulated salt leads to n-doping of nanotubes. The detailed multifrequency Raman spectroscopy investigation of the alteration of Raman modes of SWCNTs upon filling is conducted. The doping-induced changes in the radial breathing mode and G-band are revealed. It is found that these changes differ for the metallic and semiconducting SWCNTs. The obtained data and revealed trends are expected to be helpful for forthcoming studies to interpret the observed changes in Raman spectra of filled metallic and semiconducting SWCNTs.
关键词： Raman spectroscopy,electronic properties,X-ray photoelectron spectroscopy,rubidium iodide,filling,single-walled carbon nanotubes
更新于2025-09-11 14:15:04
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Formation of Highly Ordered Terminal Alkyne Self-Assembled Monolayers on the Au{111} Surface through Substitution of 1-Decaboranethiolate
摘要： The reaction aimed at completing and closing the open cages of 1-decaboranethiol self-assembled monolayers (SAMs) on Au{111} with 4-phenyl-1-butyne results in highly ordered monolayers of 4-phenyl-1-butyne. The initially disordered 1-decaboranethiolate changed into ordered (√3×√3)R 30° lattices on Au{111} typical of alkyne SAMs, indicating the complete substitution of 1-decaboranethiolate moieties, as determined by nanoscale imaging with scanning tunneling microscopy and X-ray photoelectron spectroscopy. Vibrational spectroscopy results indicate that the process happens gradually and that alkynyl groups are not totally oxidized in the ordered 4-phenyl-1-butyne monolayer.
关键词： Au{111},self-assembled monolayers,vibrational spectroscopy,scanning tunneling microscopy,X-ray photoelectron spectroscopy,4-phenyl-1-butyne,1-decaboranethiol
更新于2025-09-11 14:15:04