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Ultraviolet and Visible Analyzers
Published in Béla G. Lipták, Analytical Instrumentation, 2018
Dispersive and nondispersive monochromators are used in photometric analysis. Spectrophotometers are dispersive instruments and photometers are nondispersive instruments. The function of the monochromator is to disperse light from a source and selectively pass a narrow spectral band to the sample and detector. The dispersing element is usually a diffractive grating which is a highly polished mirror with a number of parallel lines scribed on its surface. For each position of the grating a narrow band of dispersed radiation passes through the exit slit. Spectrophotometers are dispersive devices that are used to scan across a spectrum of wavelengths; they can be used to make measurements at several wavelengths. This capability allows for the analysis of multiple components with a spectrophotometer.
Polarization Measurement
Published in John G. Webster, Halit Eren, Measurement, Instrumentation, and Sensors Handbook, 2017
The simplest source is a polarized laser. The monochromatic source system in Figure 49.7 is usually used in visible, ultraviolet, and infrared spectrometers. Light from a lamp source L is focused by a lens system or a spherical mirror system onto the entrance slit of a grating monochromator M. Light leaving the exit slit of M is collimated by another lens system and a set of iris apertures. The longpass filter F in the detector arm is used with a grating monochromator to remove undesired short-wavelength radiation. Choices of monochromators include a grating monochromator, prism monochromator, or Fourier transform spectrometer. A spectrometer is a necessary component for a spectroscopic ellipsometer. Synchrotron radiation is also a continuum source and is used to replace the lamp in the vacuum ultraviolet region [25]. The synchrotron radiation beam is intense and polarized. Grazing incidence reflection optics is usually used to avoid absorption in the components.
Infrared devices and techniques
Published in John P. Dakin, Robert G. W. Brown, Handbook of Optoelectronics, 2017
Antoni Rogalski, Krzysztof Chrzanowski
A monochromator is an optical instrument that uses a dispersing component (a grating or a prism) and transmits to the exit slit (optionally directly to the detector) only a selected spectral fraction of the radiation incoming to the entrance slit. The center wavelength of the transmitted spectral band can be changed within the instrument’s spectral region by rotating the dispersing element. Very good spectral resolution can be achieved using grating monochromators (as high as 0.1% of the wavelength). However, the monochromator transmits the optical radiation only in a very narrow spectral band. Moerover, grating monochromators are designed using low speed optics. As a result, the optical detectors at the output of the monochromators receive only a very small fraction of the radiation incoming to the monochromator input. Therefore, spectroradiometers built using grating monochromators suffer poor sensitivity. Cooled optical detectors of ultra-high sensitivity are often used in such spectroradiometers to reduce the aforementioned drawback, however with a limited effect.
Effect of particle loading and temperature on the rheological behavior of Al2O3 and TiO2 nanofluids
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2022
Pritam Kumar Das, Santosh Kumar Dash, Ranjan Ganguly, Apurba Kumar Santra, Elumalai Perumal Venkatesan, Ali A. Rajhi, Saboor Shaik, Asif Afzal
Ultraviolet-visible (UV) spectroscopy was used to identify the stability of nanofluid. It measures reflectance in the ultraviolet-visible spectral area, which denotes the attenuation of light after it crosses through a sample. The UV light source is divided into its constituent wavelengths by a prism. Measurements are made by pouring the nanofluid samples into a cuvette through which the e. m. radiations are passed. The cuvette has two exceptionally cleaned surfaces to limit reflection and scattering losses, and the other two faces were permitting the light bar. After the preparation of the nanofluid, a sample was filled into a cuvette for testing. The nanofluid scatterings are commonly estimated by utilizing a spectrophotometer at a range of wavelengths from 200–1100 nm. The most widely recognized spectrophotometers are utilized in the ultraviolet (λ < 380 nm) and the visible (380 < λ < 780 nm) ranges of e. m. range and some could likewise work in close infrared (780 < λ < 1500 nm) locale. The UV spectroscopy for any solution bears a connection between the absorbance of light and the incident wavelength. A Shimadzu UVPC-1601 spectrophotometer of wavelength between 200–1100 nm has been used for spectral transmittance measurement. A schematic outline of the relevant setup is described in Figure 2. The sample is placed in a quartz vial when a halogen light is passed through the monochromator. The probing light signal, generated from the monochromator (a combination of prism and grating system) is allowed to pass through the sample, and the transmitted light is picked up by photodetector, and analyzed. Nanofluids’ wavelength peaked with absorbency >1 between 280 and 400 nm, which demonstrated high stability (Ali, Teixeira, and Addali 2018).
Photoconductivity study of ZnxS1-x thin film using multiple light sources
Published in Phase Transitions, 2022
Kayode Oladele Olumurewa, Saheed Adekunle Adewinbi, Alexandra Adesina Willoughby, Marcus Adebola Eleruja
The photoconductivity of the thin film of ZnxS1-x was studied at room temperature using a monochromator. Mercury lamp, tungsten lamp and sodium lamp were used as the source of the incident light and focused into the slit opening of the monochromator in a dark room. The wavelength of the monochromator varied from 250 to 750 nm. The light ray from the monochromator was incident on the film and the resistance of the film was measured at a specific wavelength. The graph of photo resistance against wavelength was plotted.