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Thursday, July 30, 2020 | History

2 edition of Chemical actinometry of high intensity 185 nm - 200 nm ultraviolet radiation. found in the catalog.

Chemical actinometry of high intensity 185 nm - 200 nm ultraviolet radiation.

Khurshid Ahmad Khan

Chemical actinometry of high intensity 185 nm - 200 nm ultraviolet radiation.

by Khurshid Ahmad Khan

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  • 16 Currently reading

Published by University of Salford in Salford .
Written in English


Edition Notes

MSc thesis, Chemistry.

ID Numbers
Open LibraryOL20309243M

An intense vacuum ultraviolet spike μs in width is observed at the initial stage of low‐pressure Xe discharge, i.e., Xe Townsend discharge, in submillimeter tubes. The intensity of the nm resonance line reaches W/cm 2, about times stronger than that obtained from the steady‐state Xe positive ency of the vacuum ultraviolet radiation exceeds 24%, or 32 lm/ W. UV C ( nm) Bactericidal or germidical region The Joint Committee on Nomenclature in Applied Spectroscopy has recommended the terms Far UV for the nm band and Near UV for the nm band. Sources of ultraviolet radiation ADMIN NOTE: Eye protection must be used with ALL sources of UV light. Incandescent sources.

According to the requirements of the "Disinfection Technical Specifications", the radiation intensity of the new UV lamp should be greater than VW/cm2 (the distance is 1m. The minimum radiation intensity of the lamp in use should reach 70VW/cm2, but the irradiation time should be extended. PROPERTIES AND MEASUREMENT OF ULTRAVIOLET RADIATION Sources The UVR spectrum may be divided into three major components which induce significantly different biological effects: UV-A -- wavelengths from nm to nm (synonyms: long wave UVR, near UVR, black light); UV-B -- to nm (synonyms: middle UVR, "sunburn" radiation); UV-C.

Döhler, G., , Impact of UV-B (– nm) radiation on metabolic processes of marine phytoplankton, in: Effects of Solar Ultraviolet Radiation on Biogeochemical Dynamics in Aquatic Environments (N. V. Blough and R. G. Zepp, eds.), WHOI, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts. Google Scholar. Radiation between and nm (UV-C) penetrates membrane cells and breaks down the DNA molecules (Shama, , ), which result in a germicidal effect (Bintsis et al., ). A maximum lethal effect of UV-C light has been reported in the range of - nm, inactivating bacteria, virus, protozoa’s, fungi and algae (Shama,


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Chemical actinometry of high intensity 185 nm - 200 nm ultraviolet radiation by Khurshid Ahmad Khan Download PDF EPUB FB2

Ultraviolet; UVB ( nm) and UVC ( nm). The adverse effects of UV radiation have been shown to be a result of photochemical reactions rather than thermal damage. This is shown by the rapid drop off of effects in the longer wavelengths of the UV spectrum.

The effectiveness of the various wavelengths of UV radiationFile Size: KB. Ultraviolet (UV) is a form of electromagnetic radiation with wavelength from 10 nm (with a corresponding frequency of approximately 30 PHz) to nm ( THz), shorter than that of visible light but longer than radiation is present in sunlight, and constitutes about 10% of the total electromagnetic radiation output from the is also produced by electric arcs and specialized.

A simple actinometry experiment that could be used in graduate or undergraduate laboratory courses is described. The photochemical reaction of o-nitrobenzaldehyde (NBA) irradiated with a medium-pressure mercury vapor lamp is used to calculate the intensity of light over the wavelength range of nm.

The reactant disappearance rate can be quantitated by gas chromatography or Cited by:   The bactericidal properties of ultraviolet radiation (UV) have been known for almost years. The main bactericide in the environment is the UV component of sunlight.

However, the vast majority of UV inactivation data for bacteria were conducted by exposing cells to nm radiation, which is absent from by:   Atmospheric Environment Vol.

Pergamon Press Printed in Great Britain. SHORT COMMUNICATIONS A CHEMICAL ACTINOMETER FOR MEASUREMENT OF U.V. RADIATION INTENSITY IN THE ATMOSPHERE Abstracthe benzophenone-benzhydrol system may serve as a very convenient chemical actinometer for measuring solar radiation intensities in the region of by: 5.

The eyes are most sensitive to UV radiation from nm to nm (UV-C and UV-B). Maximum absorption by the cornea occurs around nm. Absorption of UV-A in the lens may be a factor in producing cataract (a clouding of the lens in the eye).

Abstract A method is demonstrated for measuring germicidal ( nm) ultraviolet radiation (GUVR) in an omnidirectional manner. This method has application for those situations in which GUVR from more than one direction or source impinges on a three‐dimensional object, and when it is of interest to determine the radiant fluence experienced by the object.

UV-visible spectrophotometer: uses light over the ultraviolet range ( - nm) and visible range ( - nm) of electromagnetic radiation spectrum. IR spectrophotometer: uses light over the infrared range ( - nm) of electromagnetic radiation spectrum.

For the actinic UV region (comprising of UV-C and UV-B from nm), the effective irradiance (Eeff) of a broadband source is determined weighted against the peak of the spectral effectiveness curve ( nm).

The permissible exposure time (s) to the source is computed, dividing 30 J.m-2 by E eff (W.m-2) (2) For measurement of UV radiation.

Germicidal lamps that generate energy wavelengths shorter than nm (particularly nm) are very effective in producing ozone, which is required for certain applications to oxidize organic compounds.

Hazard and Risks from Germicidal Lamp UV Radiation. UV radiation (UVR) used in most germicidal bulbs is harmful to both skin and eyes, and. It is shown that the photon flux intensity produced by the source within the spectral range of nm reaches x10{sup 23} photons/cm{sup 2} s corresponding to the effective brightness temperature of discharge plasma of 20 kK and to the intrinsic efficiency of the discharge VUV emission of %.

Chemical Actinometry reactor can be also operated for the determination of the activity of photocatalytic materials in a slurry under very high radiation fluxes. The nm UV-LEDs. Synchrotron light sources generate fluxes ranging from 10 10 to >10 13 photons/sec at nm, which remain constant well into the vacuum UV [62,63], allowing measurements with high signal-to-noise down to nm (or below for non-aqueous solutions).

This permits the detection of subtle conformational changes, which may, for example, prove. UV radiation at nm is used to generate ozone. The UV lamps for water treatment consist of specialized low-pressure mercury-vapor lamps that produce ultraviolet radiation at nm, or medium-pressure UV lamps that produce a polychromatic output from nm to visible and infrared energy.

UV intensity measurement for a novel nm excimer lamp using chemical actinometer Article (PDF Available) in Applied Surface Science February with 1, Reads.

Ultraviolet lamps are used to sterilize workspaces and tools used in biology laboratories and medical facilities. Commercially-available low pressure mercury-vapor lamps emit about 86% of their light at nanometers (nm) which coincides very well with one of the two peaks of the germicidal effectiveness curve (i.e., effectiveness for UV absorption by DNA).

* Original data are 8 pW cm-2 for UV-A plus UV-B spectral regions and 3,8 11 pW cm-2 for the visible region ( nm). lated to zero irradiation time to correct for absorption due to internal filtering by the ONBA product. In Fig. 1 we compare the ab. the spectrum is the wavelength of the radiation.

UV radiation spans the wavelength region from to nm. Even in the UV portion of the spectrum the bio-logical effects of the radiation vary enormously with wavelength and for this reason the UV spectrum is further subdivided into three regions.

The notion to. Electromagnetic radiation - Electromagnetic radiation - Ultraviolet radiation: The German physicist Johann Wilhelm Ritter, having learned of Herschel’s discovery of infrared waves, looked beyond the violet end of the visible spectrum of the Sun and found (in ) that there exist invisible rays that darken silver chloride even more efficiently than visible light.

Ultraviolet (UV) light is electromagnetic radiation with a wavelength shorter than that of visible light, but longer than X-rays, in the range 10 nm to nm, and energies from 3 eV to eV. It is named because the spectrum consists of electromagnetic waves with frequencies higher than those that humans identify as the color violet.

Although ultraviolet radiation is invisible to the human. A light-emitting diode (LED) is a semiconductor light source that emits light when current flows through it. Electrons in the semiconductor recombine with electron holes, releasing energy in the form of color of the light (corresponding to the energy of the photons) is determined by the energy required for electrons to cross the band gap of the semiconductor.Overview of UV Disinfection Light that is absorbed by a system can induce a chemical reaction.

As shown in Figureeach of the nucleotides absorbs UV light from to nm (section A). The UV absorption of DNA results from the combination of nucleotides and has a peak near nm and a local minimum near nm.Description: UV medium-pressure lamps feature a broad, pronounced line spectrum in the ultraviolet and visible range ( nm to nm) and a high power density of about W/cm².

They are suitable for UV disinfection, UV oxidation, UV curing and photochemical processes. Lamp Power: 1 to 60 watts; Lamp Type: UV Lamps Rated Average Life: hours.