Ultraviolet light characteristic wavelengths

In Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES), a gaseous, solid (as fine particles), or liquid (as an aerosol) sample is directed into the center of a gaseous plasma. The sample is vaporized, atomized, and partially ionized in the plasma. Atoms and ions are excited and emit light at characteristic wavelengths in the ultraviolet or visible region of the spectrum. The emission line intensities are proportional to the concentration of each element in the sample. A grating spectrometer is used for either simultaneous or sequential multielement analysis. The concentration of each element is determined from measured intensities via calibration with standards. 

Approximately 70 different elements are routinely determined using ICP-OES. Detection limits are typically in the sub-part-per-billion (sub-ppb) to 0.1 part-per-million (ppm) range. ICP-OES is most commonly used for bulk analysis of liquid samples or solids dissolved in liquids. Special sample introduction techniques, such as spark discharge or laser ablation, allow the analysis of surfaces or thin films. Each element emits a characteristic spectrum in the ultraviolet and visible region. The light intensity at one of the characteristic wavelengths is proportional to the concentration of that element in the sample. 

The output from a ruby giant-pulse laser (2 Joule, 30 nsec half-width, = 6943A) passes a KH2PO4 crystal where, due to the nonlinear characteristics of this material, the second harmonic at X = 3471 A is generated with an efficiency of 3 %.The two wavelengths are separated by means of a water filled quartz prism. The ultraviolet light pulse serves as pump pulse. 

Tryptophan and tyrosine, and to a much lesser extent phenylalanine, absorb ultraviolet light (Fig. 3-6 Box 3-1). This accounts for the characteristic strong absorbance of light by most proteins at a wavelength of 280 nm, a property exploited by researchers in the characterization of proteins. 

While there appears to be some discrepancy in the conclusions derived from these studies, the difference can be explained as being caused by the exposure conditions. To illustrate the effect of irradiation wavelength on the photooxidation, unstabilized polystyrene films were exposed to the following three ultraviolet light sources having different emission characteristics (Figure 16) ... 

The intensity of visible, infrared, and ultraviolet light produced by the sun and reflected by a solar-system body as a function of wavelength. Such spectra can be characteristic of the chemical compounds that occur on the surface of that body as well as surface temperature. 

Spectroscopy n The study of electromagnetic waves that are absorbed or emitted by substances when excited by the arc, a spark, X rays, or a magnetic field. Each element emits light of characteristic wavelengths, by which minute quantities can be detected and estimated. An example of a spectrophotomer for the ultraviolet and visible spectrum is the PerkinElmer Lambda 25/35/45 UV/VIS (courtesy of PerkinElmer. Inc.). See also Nuclear Magnetic Resonance. 

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