A Study on the Optoelectronics Parameters of Natural Dyes Extracted From Beetroot, Cabbage, Walnut and Henna For Potential Applications in Organic Electronics

In this work, the optoelectronic parameters of natural dyes extracted from beetroot, red cabbage, walnut leaves, and henna are determined and investigated. These include optical energy gap (Eg), extinction coefficient (k), refractive index (n), dielectric constant ( εr ) and optical conductivity ( σr ). Results showed that cabbage dye exhibited a maximum values of n=6.08, εr = 37.18 and σr = 13.92 * 10-3S/cm, while henna dye presented the lowest values of n = 1.19, εr = 1.5 and σr = 0.039 * 10-3S/cm compared to the optoelectronic parameters of the other studied samples. The optical absorption in the dyes were found to obey a direct allowed transition between the molecular energy levels. The results presented here can be of a special importance for some potential applications in organic electronics such as organic photovoltaics and sensors.

Microwave-Assisted Synthesis of Titanate Nanotubes Loaded with Platinum with Enhanced Selectivity for Photocatalytic H2 Evolution from Methanol

Titanate nanotubes (TNTs) fabricated through microwave-assisted synthesis were examined for their ability to catalyze hydrogen production from a 20% v/v methanol solution under UV and visible light irradiation. Herein, TiO2 was used not only as the raw material for TNT synthesis but also as a reference support to compare its performance with that of TNTs. The UV–Vis spectral analyses of the TNT composites showed greater shifts toward the visible region after Pt loading than the spectra of Pt/TiO2. Moreover, using the Kubelka–Munk equation and Tauc Plot method, we determined that the direct allowed transition in TNT composites was more probable than the indirect allowed transition. The photocatalytic performances were evaluated by measuring the hydrogen production, and the experimental results showed that Pt/TNTs exhibited higher activity than Pt/TiO2. Furthermore, bare TNTs and Pt/TNTs showed lower CO generation than bare TiO2 and Pt/TiO2. As such, TNT composites enhanced the photocatalytic selectivity for H2 generation from formic acid to a greater extent than Pt/TiO2, because the kinetic diameter of CO (0.38[Formula: see text]nm) is larger than that of CO2 (0.33[Formula: see text]nm). This result may be attributed to the inability of CO to diffuse into the pores of TNTs because of the diameter difference. Also, XPS results showed negative shifts of Pt binding energies and positive shifts of Ti binding energies due to the strong metal-support interaction between Pt and TNTs. Thus, the remarkably high photocatalytic efficiency of TNT composites facilitates their application as promising photocatalysts.

Experimental study of 𝛽 spectra using Si detectors

Several scientific users from different communities, such as nuclear medicine, ionizing radiation metrology, nuclear energy industries, and fundamental physics are seeking for a precise knowledge of beta spectra. Consequently, it is of great interest to investigate the spectral shape of beta decaying nuclei with best possible precision. In this work, we aim to investigate precisely β~ decays. For this purpose, we have developed a quasi 4π beta spectrometer based on Silicon detectors (PIPS®). The measurement system is characterized by conversion electron peaks of 109Cd and 207Bi and has been compared with Monte Carlo simulations using nuclear decay data. The preliminary measurements of 14C (allowed transition) and 36Cl (second forbidden non-unique transition) decays have been performed and compared with simulations using the PENELOPE Monte Carlo code.

Study of Structural and Optical Properties of Non-Oxide Se90Cd10–xSbx(2 ≤ x ≤ 8) Chalcogenide Thin Films

Thin films of Se90Cd10–xSbx (2 ≤ x ≤ 8) of thickness 0.4 microns were prepared on ultra-clean glass substrate by thermal evaporation technique. The vacuum level was 10–6 torr. This paper intends to investigate the impact of Sb concentration on the optical characterization. XRD measurement has been done to investigate the Structural characterization of the prepared thin films. XRD result indicates the prepared thin have amorphous nature. To analyze the optical characterization of the thin films the absorption spectra were recorded over 400–1100 nm wavelength range. In the present study the optical absorption follows direct allowed transition. An increase in photon energy causes an increase in absorption coefficient while extinction coefficient has been found to increase with an increase in frequency of the photons i.e., deceases with increase of wavelength. Optical bandgap (Eg) of thin films have been studied and an increase in it has been recorded with increasing Sb concentration.

Structural and optical properties of CdS:Sn thin films prepared by chemical spray pyrolysis method

CdS and CdS:Sn thin films were successfully deposited on glasssubstrates by spray pyrolysis method. The films were grown atsubstrate temperatures 300 C°. The effects of Sn concentration on thestructural and optical properties were studied.The XRD profiles showed that the films are polycrystalline withhexagonal structure grown preferentially along the (002) axis. Theoptical studies exhibit direct allowed transition. Energy band gapvary from 3.2 to 2.7 eV.

Synthesis and Structural Analysis of Powder Complex of Tris(bipyridine)cobalt(II) Trifluoromethanesulfonate Octahydrate

The powder complex of tris(bipyridine)cobalt(II) trifluoromethanesulfonate octahydrate has been synthesized by direct interaction of the corresponding aqueous solutions (and drops of ethanol) of cobalt(II) nitrate, bipyridine, and potassium triflate. The yellow-orange powder produced was filtered off and allowed to dry on an aeration for characterization. AAS measurement showed the content of metal to be 6.06%, corresponding to the theoretical value of 6.06% in [Co(bipy)3](CF3SO3)2.8H2O. The analysis of conductance producing the charge ratio of cation to anion to be 2:1, confirms the formula. The magnetic moment, µeff, of this complex which was to be 4.5-4.9 BM, indicates that the complex is paramagnetic corresponding to the three unpaired electrons with a significantly orbital contribution. UV-Vis spectrum of the complex reveals the first band observed at about 11100 cm–1, which is associated with the spin-allowed transition, 4T1g → 4T2g. A distinct shoulder at only about 16100 cm–1 should be associated with the spin-forbidden transition of 4T1g → 2T2g,2T2g (G). The expected second and third bands which are associated with spin-allowed transitions of 4T1g → 4T1g(P) and 4T1g → 4A2g at higher energy were not well resolved. The infrared spectrum shows absorptions of the functional group of ligand which is influenced by the metal-ligand interaction in this complex. The powder XRD of this complex was refined using Le Bail method of Rietica program and found to be fit as monoclinic symmetry with a space group of C2/c.

Structural, optical and electrical properties of thermal evaporated nano sized In2Te3 thin films

Indium Telluride thin films were prepared by thermal evaporation technique. Films were annealed at 573K under vacuum for an hour. Both as-deposited and annealed films were used for characterization. The structural parameters were discussed on the basis of annealing effect for a film of thickness 1500 Å. Optical analysis was carried out on films of different thicknesses for both as - deposited and annealed samples. Both the as- deposited and annealed films exhibit direct and allowed transition. Electrical resistivity measurements were made in the temperature range of 303-473 K using Four-probe method. The calculated resistivity value is of the order of 10-6 ohm meter. The activation energy value decreases with increasing film thickness. The negative temperature coefficient indicates the semiconducting nature of the film.

Spectroscopic Studies on Films of Lead Nitrate Doped Polyvinyl Alcohol – Polyvinyl Pyrrolidone Blend

Films of polyvinyl alcohol (PVA) – polyvinyl pyrrolidone (PVP) blend doped with lead nitrate (Pb(NO3)2) were prepared by solution casting method, with doping level (DL) of Pb(NO3)2 in PVA – PVP polymeric blend varying from 2.7 up to 50.5 wt%. The prepared films were characterized using UV-Visible spectroscopy, fluorescence (or photo- luminescence) spectroscopy, FTIR and Raman spectroscopy. Parameters like optical band gaps due to indirect allowed transition (IAT) and direct allowed transition (DAT), as well as the activation energy (Ea) for optical transitions are extracted from the UV- Visible (or optical) spectra of these films. Objective of the FTIR, Raman and Fluorescence spectroscopic study is to understand the molecular chemical changes in PVA and PVP caused by the dopant (Pb(NO3)2). There is an enhancement of fluorescence intensity at DLs of 2.7 wt%, and at DL 7.6 wt%, the fluorescence intensity decreases (quenching). PVP acts as a capping agent for the dopant species, and is considered to be responsible for changes in fluorescence intensity. Signature of nitrate ion (NO3-) vibration is observed at wavenumber 1037 cm-1 in Raman spectra, and in the FTIR spectra, the NO3- vibration is seen at the wavenumber equal to 1380 cm-1.