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Understanding Light in Optical Microscopy
Published in John Girkin, A Practical Guide to Optical Microscopy, 2019
Before the advent of lasers, arc lamps were the brightest light sources available. Crucially for microscopy the light can be produced in a very small volume and thus re-imaged into the sample for very high intensity illumination, even if the source is spectrally filtered. In all arc lamps a visible discharge in a gas is produced by striking an arc. The arc is then maintained through the current supplied. Generally the intensity of the arc cannot be altered as changing the power can cause intensity instabilities, thus the intensity is controlled by filters or apertures. The arc is normally instigated and controlled by an electrical discharge but lamps in which the arc is driven by a laser diode are now available with very high powers. Arc lamps offer very intense illumination but at a high cost in electrical energy, heat production and money! They also have a limited lifetime that needs to be monitored.
Incoherent Light Sources
Published in Daniel Malacara-Hernández, Brian J. Thompson, Advanced Optical Instruments and Techniques, 2017
The starting voltage for a short arc lamp may rise up to 40 kV. To avoid a rapid destruction of the lamp due to a high current, ballast must be used. For ac operation, inductive ballasts are used, but for many applications where line current modulation is not allowed, an electronic current limiter must be provided after the start. Three short arc lamps are available: mercury and mercury—xenon, xenon lamps, and metal halide lamps.
Lighting: From Human Evolution to Sustainable Revolution
Published in Azzedine Boudrioua, Roshdi Rashed, Vasudevan Lakshminarayanan, Light-Based Science: Technology and Sustainable Development, 2017
Indeed, innovation progressed beyond the limitations and energy requirements of the carbon filament. In the quest for a more efficient technology, several families of gas discharge bulb were created including the fluorescent lamp, in which an electrical current is passed through mercury vapour, exciting the molecules which emit ultraviolet light. This light is then absorbed by a phosphor coating inside the lamp which causes it to glow, or fluoresce. Fluorescent lighting came to be widely used in office and industry lighting applications because of its energy efficiency in relation to light output as compared to incandescent lamps. Compact fluorescent lamps (CFL) were later developed to replace incandescent lamps in the home. Additionally, high intensity discharge (HID) lamps, utilising an electrical arc between tungsten electrodes mounted in a gas medium, built upon the earlier technology of the simple arc lamp to deliver more visible light per unit of electricity than either incandescent or fluorescent lamps before them. This family of lamp types is used primarily for outdoor applications such as the lighting of streets, stadiums and retail locations (Figure 13.2).
Highly selective detection of Fe3+ and nitro explosives by a bifunctional sensor based on Cd(II) complex
Published in Inorganic and Nano-Metal Chemistry, 2022
Bo Zhao, Hao Liu, Yanan Gu, Qiaozhen Sun
All the reagents and solvents for synthesis and analysis were commercially available. Elemental analysis (C, H contents) was measured on a Perkin-Elmer 240 analyzer. Infrared Resonance (IR) spectrum was recorded on a Vector 22 Bruker spectrophotometer with KBr pellets in the 4000 − 400 cm−1 regions at room temperature. Thermogravimetric analyses (TGA) were performed on a Perkin − Elmer thermal analyzer at a heating rate of 10 °C/min under nitrogen atmosphere. Powder X-ray diffraction (PXRD) patterns were recorded on a Rigaku D/max-2550 X-ray diffractometer with graphite monochromatic Cu-Ka (1.54056 Å) radiation at 40 kV/250 mA at room temperature. Luminescence spectra of the samples were recorded on a FLS920 spectrophotometer with a xenon arc lamp as the light source at room temperature. X-ray photoelectron spectra (XPS) were obtained by a Thermo Scientific Escalab250Xi spectrometer. UV − Vis spectra were obtained using a UV − Vis spectrophotometer with a dissolution cell of 10 mm path.
Redox, spectroscopic, photo-induced ligand exchange, and DNA interaction studies of a new Ru(II)Pt(II) bimetallic complex
Published in Journal of Coordination Chemistry, 2018
Avijita Jain, Kaitlyn R. Wyland, Denali H. Davis
The photo-induced ligand exchange was determined by monitoring the changes in the electronic absorption spectrum of the complex as a function of irradiation time in water. Photolysis experiments were performed using an Oriel 450 W xenon arc lamp. The light was passed through a 550 nm cutoff filter. Figure 5 displays changes in the electronic absorption spectra of [Ru(biq)2(dpp)PtCl2](PF6)2 in water upon irradiation time for 0–80 s. The photolysis of the complex resulted in a decrease in the MLCT band centered at 545 nm and the appearance of a band centered at 590 nm, consistent with the formation of complex [Ru(biq)2(H2O)2]2+. The increase in absorbance at 339 nm is attributed to the formation of complex [Ptdpp(H2O)2]2+, consistent with previous reports [46]. The isosbestic points were observed at 357 and 573 nm. The designed Ru(II)Pt(II) complex was found to be inert to ligand substitution in the dark at room temperature for 24 h. The kinetics of the ligand exchange reaction was measured by plotting change in absorbance at 546 nm as a function of irradiation time (inset, Figure 5).
Effect of various factors and hygrothermal ageing environment on the low velocity impact response of fibre reinforced polymer composites- a comprehensive review
Published in Cogent Engineering, 2023
Oshin Fernandes, Jyoti Dutta, Yogeesha Pai
Kim et al. (2005) studied the damage mechanisms and compressive residual strength variation of glass/phenolic laminate by LVI loading under accelerated ageing environment. Accelerated ageing was conducted which consisted of xenon arc lamp irradiation at 60 ℃ and 60% humidity for 250 cycles (500 h.), 500 cycles (1000 h.), and 750 cycles (1500 h.). The results demonstrate that failure initiation energy and resultant compressive strength decrease as ageing time increased. Surface degradation due to ultraviolet light results in reduction of failure initiation energy as ageing cycles increase. The damage processes observed in the damage area were matrix cracking, delamination, fibre breakage, and finally penetration.