Light sources mercury lamps

Figure 132. Stabilization of cianidanol against photodegradation (light source mercury lamp) in the solid state by the use of an oxygen absorbent, o With oxygen absorbent without oxygen absorbent. (Reproduced from Ref. 402 with permission.)...

A distinction must be made between continuous sources (hydrogen or deuterium lamps, incandescent tungsten lamps, high pressure xenon lamps) and spectral line sources (mercury lamps), which deliver spectrally purer light in the region of their emission lines. 

Figure 5. Dependence of rate of dissolution of 5pM Y-FeOOH in pH 4.0, 0.01M NaCl on concentration of a) tartaric acid, and b) salicylic acid. Fitted parameters obtained for rectangular hyperbolic model are given. Light source mercury arc lamp with 365nm band-pass filtering.

Figure 7. Dissolution of 5ijM 6-Mn02 in pH 7.1, 0.01M NaCl/2mM NaHC03 solutions containing 10 mg/L Suwanee River fulvic acid under dark and light conditions in the presence and absence of oxygen. Light sources mercury arc lamp with 365nm band-pass filtering. (Reproduced from Ref. 45.).

A conventional fluorescence microscope differs from a standard microscope by the light source (mercury or xenon lamp), which produces UV-visible light. The excitation wavelength is selected by an interference filter or a monochromator. Observation of the fluorescence is made by eye, photographic film or CCD (charge-... 

Figure 13. Line and continuous spectra from various light sources ----= Xenon lamp -------= Mercury vapor arcs .= Hydrogen lamp...

Light source deuterium lamp or mercury lamp (for 2,2,2-trifluoro-l-(9-anthryl)ethanol] Wavelength = 254 nm or = 366 nm, = 420 nm (cutoff filter) (for anthryl derivative) Slit 6 X 0.2 mm Scanning 0.05 mm... 

Light sources can either be broadband, such as a Globar, a Nemst glower, an incandescent wire or mercury arc lamp or they can be tunable, such as a laser or optical parametric oscillator (OPO). In the fomier case, a monocln-omator is needed to achieve spectral resolution. In the case of a tunable light source, the spectral resolution is detemiined by the linewidth of the source itself In either case, the spectral coverage of the light source imposes limits on the vibrational frequencies that can be measured. Of course, limitations on the dispersing element and detector also affect the overall spectral response of the spectrometer. 

Scandium iodide added to mercury vapor lamps produces a highly efficient light source resembling sunlight, which is important for indoor or night-time color TV. 

In contrast to spectrophotometry, hght-scattering experiments are generally conducted at constant wavelength. Mercury vapor lamps are the most widely used light sources, since the strong lines at 436 and 546 nm are readily isolated by filters to allow monochromatic illumination. Polarizing filters are also included for both the incident and scattered beams so that depolarization can... 

Ultraviolet light sources are based on the mercury vapor arc. The mercury is enclosed ia a quart2 tube and a potential is appHed to electrodes at either end of the tube. The electrodes can be of iron, tungsten, or other metals and the pressure ia a mercury vapor lamp may range from less than 0.1 to >1 MPa (<1 to >10 atm). As the mercury pressure and lamp operating temperatures are iacreased, the radiation becomes more iatense and the width of the emission lines iacreases (17). 

Radiation of a particular wavelength (monochromatic) is required to initiate a specific electronic transition, but most UV and visible light sources are polychromatic. For example, common mercury arc lamps emit around 50% of their energy in the 405 nm to 578 nm range. Hence, for most processes, well over half of the electrical energy... 

Light sources are often expensive, especially if made of thick-walled quartz as in high-pressure mercury lamps, and delicate, so that equipment costs may be high compared to thermal processes. 

The optimum wavelength for UV sterilization is around 260 nm. A suitable source for UV light in this region is a mercury lamp giving peak emission levels at 254 nm. These sources are generally wall- or ceiling-mounted for air disinfection, or fixed to vessels for water treatment. Operators present in an irradiated room should wear appropriate protective clothing and eye shields. 

P 32] Pyrene (20 mM), 1,4-dicyanobenzene (40 mM) and sodium cyanide (1 M) were reacted in propylene carbonate and water. A 100 pi solution of pyrene (20 mM), 1.4-dicyanobenzene (40 mM) in propylene carbonate and a 100 pi solution of sodium cyanide (1 M) in water were fed by programmable dual-syringe pumps via fused-silica capillary tubes into a micro-channel chip [29]. Both solutions were fed with equal flow velocity. A 300 W high-pressure mercury lamp was used as light source. After passing an optical filter made of a CUSO4 solution, the whole chip was irradiated after formation of a stable oil/water interface inside. The oil phase was collected at the exit. 

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