Ultraviolet applications

Bolton JR. Ultraviolet Applications Handbook. London, Ontario Bolton Photosciences, 1999. 

Bolton )R (1999) Ultraviolet Applications Handbook, Bolton Photosciences Inc., Ayr, Ontario, Canada, ISBN 0-9685432-0-0 also published in Europ. Photochem. Assoc. Neml. Nr. 66 9-36. 

Bolton JR (2001) Ultraviolet Applications Handbook, 2" ed., Bolton Photosciences Inc., 628 Cheriton Cres., NW, Edmonton, AB, Canada T6R 2M5, ISBN 0-9685432-1-9. 

Antireflection coatings for infrared materials such as Si, Ge, InAs and InSb have been designed extensively by Cox and various coworkers [59-61]. A commercially available multilayer broadband a.r. system for Ge is shown in Fig.6. For ultraviolet applications, only MgF2 single layers or double layers are used because of the lack of suitable high-index film materials which would satisfy the requirements for half wave films. 

Photoemissive devices can be conveniently divided into two historical (and performance) classes depending upon the material used as the photoemissive layer [5.11]. The first class is the classical group [5.26]. Here the photoemitter is a thin evaporated-layer compound containing an alkali metal or metals (almost always including Cs), one or more other metallic elements from group VB of the periodic table (e.g., Sb), and possibly also oxygen and/or silver [5.27], For ultraviolet applications several other sensor materials are used (e.g., Csl), but such devices become highly specialized and are not discussed further in this chapter [5.28]. 

Note that in liquid phase chromatography there are no detectors that are both sensitive and universal, that is, which respond linearly to solute concentration regardless of its chemical nature. In fact, the refractometer detects all solutes but it is not very sensitive its response depends evidently on the difference in refractive indices between solvent and solute whereas absorption and UV fluorescence methods respond only to aromatics, an advantage in numerous applications. Unfortunately, their coefficient of response (in ultraviolet, absorptivity is the term used) is highly variable among individual components. 

Application of the exact continuum analysis of dispersion forces requires significant calculations and the knowledge of the frequency spectmm of the material dielectric response over wavelengths X = 2irc/j/ around 10-10 nm. Because of these complications, it is common to assume that a primary absorption peak at one frequency in the ultraviolet, j/uv. dominates the dielectric spectrum of most materials. This leads to an expression for the dielectric response... 

Hepburn J W 1995 Generation of coherent vacuum ultraviolet radiation applications to high-resolution photoionization and photoelectron spectroscopy Laser Techniques in Chemistry vol 23, ed A B Myers and T R Rizzo (New York Wley) pp 149-83... 

A,7. APPLICATIONS OF INFRARED AND ULTRAVIOLET SPECTRA TO ORGANIC CHEMISTRY ... 

Section A,7, Applications of infrared and ultraviolet absorption spectra to organic chemistry, should provide a brief introduction to the subject. 

The focus of this section is the emission of ultraviolet and visible radiation following thermal or electrical excitation of atoms. Atomic emission spectroscopy has a long history. Qualitative applications based on the color of flames were used in the smelting of ores as early as 1550 and were more fully developed around 1830 with the observation of atomic spectra generated by flame emission and spark emission.Quantitative applications based on the atomic emission from electrical sparks were developed by Norman Lockyer (1836-1920) in the early 1870s, and quantitative applications based on flame emission were pioneered by IT. G. Lunde-gardh in 1930. Atomic emission based on emission from a plasma was introduced in 1964. 

Optical Applications. Vitreous siUca is ideal for many optical appHcations because of its excellent ultraviolet transmission, resistance to radiation darkening, optical polishing properties, and physical and chemical stabiUty. It is used for prisms, lenses, cells, wiadows, and other optical components where ultraviolet transmission is critical. Cuvettes used ia scatter and spectrophotometer cells are manufactured from fused siUca and fused quart2 because of the transmissive properties and high purity (222). 

ICP-OES is one of the most successful multielement analysis techniques for materials characterization. While precision and interference effects are generally best when solutions are analyzed, a number of techniques allow the direct analysis of solids. The strengths of ICP-OES include speed, relatively small interference effects, low detection limits, and applicability to a wide variety of materials. Improvements are expected in sample-introduction techniques, spectrometers that detect simultaneously the entire ultraviolet—visible spectrum with high resolution, and in the development of intelligent instruments to further improve analysis reliability. ICPMS vigorously competes with ICP-OES, particularly when low detection limits are required. 

The commercial polymers are of comparatively low molecular weight (M = 25 000-60 000) and whilst being essentially linear may contain a few branches or cross-links arising out of thermal oxidation. Exposure to ultraviolet light causes a rapid increase in gel content, whilst heating in an oven at 125°C causes gelation only after an induction period of about 1000 hours. Eor outdoor applications it is necessary to incorporate carbon black. The polymers, however, exhibit very good hydrolytic stability. 

Besides resin and reactive diluent, additives are commonly incorporated into polyester resins. These include not only curing agents and fillers (see Section 25.2.3) but also ultraviolet stabilisers. The latter are particularly important for outdoor applications such as roof lighting, benzotriazoles being particularly effective. 

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