Theoretical simulations of the angle-resolved ultraviolet photoemission spectra (ARUPS) for the oligomer of poly(tetrafluoroethylene) [(CF(2))(n); PTFE] were performed using the independent-atomic-center approximation combined with ab initio molecular orbital calculations. Previously observed normal-emission spectra for the end-on oriented sample (with long-chain axis perpendicular to the surface) showed the incident photon-energy (hnu) dependence due to the intramolecular energy-band dispersion along the one-dimensional chain, and the present simulations successfully reproduced this hnu dependence of the observed spectra. We employed the experimentally observed helical structure for PTFE oligomers for the simulations. We also calculated the density of states (DOS) for the planar zigzag structure, and examined the changes in the electronic structure due to the difference in the molecular structure by comparing the DOS for the helical and planar zigzag structures. Only a small change in the DOS was found between these structures, showing little change of the electronic structure between these conformations. We also evaluated the inner potential V(0), which is the parameter defining the energy origin of the free-electron-like final state, and checked the validity of the value of -10 eV estimated in our previous study using the experimentally observed hnu dependence of the peak intensity. The estimation of V(0) was performed by pursuing the best agreement between the energy-band dispersion [E=E(k)] relation along the chain direction obtained from the simulated spectra and the experimentally deduced one. An excellent agreement in the topmost band was achieved when the assumed inner potential V(0) was set at about zero. This value of V(0) is much different from the value of V(0)=-10 eV in the previous study, suggesting the invalidity of the previous assumption at the estimation of V(0) from the peak intensity variation with hnu. Using the presently obtained V(0), we could derive more reliable E=E(k) dispersion relation from the observed ARUPS spectra. The comparison of this newly derived relation gave good agreement with theoretically calculated E=E(k) relations, in contrast to the poor agreement for the previous results with V(0)=-10 eV.
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http://dx.doi.org/10.1063/1.1651065 | DOI Listing |
Heliyon
December 2024
Chemistry Department, Faculty of Science, Cairo University, Giza, 12613, Egypt.
The extensive use of azo dyes in textile and pharmaceutical industries pose significant environmental and health risks. This problem requires to be tackled forthwith through a cheap, environmentally friendly and viable approach to mitigate water pollution. In this context, the green synthesis method was used for synthesis of ZnO NPs.
View Article and Find Full Text PDFJ Fluoresc
December 2024
Department of Applied Physics, Delhi Technological University, Bawana Road, Delhi, 110042, India.
In the present research work, a solid-state reaction method was employed to synthesize a series of CaGdSbWO:SmEu (x = 1, 1.5, 2, 3 and 4 mol%) phosphors. The phase purity, crystallinity, morphological and compositional studies were analysed via X-ray diffraction (XRD), scanning electron microscopy (SEM) imaging, and energy dispersive spectroscopy (EDS) analysis.
View Article and Find Full Text PDFAnal Chem
December 2024
Nano Materials Laboratory, Department of Physics, Faculty of Engineering and Technology, V. B. S. Purvanchal University, Jaunpur, Uttar Pradesh 222003, India.
Liquefied petroleum gas (LPG) is a modern fuel for kitchens, vehicles, and industry. Leakage of LPG is extremely fatal for humans and the atmosphere; therefore, quick detection is a vital need. The sol-gel self-combustion process was applied to synthesize the calcium-doped praseodymium orthoferrite (PrFeO) nanomaterials.
View Article and Find Full Text PDFSmall
November 2024
Shandong Provincial Key Laboratory of Chemical Energy Storage and Novel Cell Technology, School of Chemistry and Chemical Engineering, Liaocheng University, Liaocheng, Shandong, 252059, China.
Atomically dispersed metal-nitrogen-carbon materials (AD-MNCs) are considered the most promising non-precious catalysts for the oxygen reduction reaction (ORR), but it remains a major challenge for simultaneously achieving high intrinsic activity, fast mass transport, and effective utilization of the active sites within a single catalyst. Here, an AD-MNCs consisting of defect-rich Fe-N sites dispersed with axially coordinated Te atoms on porous carbon frameworks (FeTe-900) is designed. The local charge densities and energy band structures of the neighboring Fe and Te atoms in FeN-Te are rearranged to facilitate the catalytic conversion of the O-intermediates.
View Article and Find Full Text PDFSci Rep
November 2024
Department of Mechanical Engineering, ULTRA College of Engineering and Technology, Madurai, 625 104, Tamil Nadu, India.
The crude leaf extract of Phragmanthera macrosolen L. has been utilized for the first time as an effective reducing, capping and stabilizing agent to synthesize silver oxide nanoparticles (AgO NPs) through a green approach. The prepared AgO NPs were analyzed by scanning electron-microscopy (SEM), High Resolution Transmission electron microscope (HR-TEM), X-ray diffractions (XRD), Fourier transforms infrared (FTIR) spectroscopy, energy dispersive spectroscopy (EDS), and Ultra-violet visible spectrometry (UV-Vis).
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