Monochromatic UV radiation

Photoionization of difluorine and chlorine monofluoride appeared to give an even lower value (68), but a reexamination showed that one of the dissociation processes had been ignored (29). In this method fluorine is exposed to monochromatic UV radiation, and the positive and negative ions are observed in a mass spectrometer. 

Excimer and nitrogen lasers are sources of pulsed monochromatic UV radiation with a variety of interesting wavelengths and high-output peak powers. 

Monochromatic UV radiation is emitted by excimer lamps, in which microwave discharge5 or a radio-frequency-driven silent discharge6 generates excimer-excited states of noble gas halide molecules, which decay by the emission of monochromatic UV radiation. In the ground state, the excimer molecules decay into atoms. Therefore, no self-absorption of the UV radiation can occur. All photons are coupled out of the discharge.4... 

Excimer and nitrogen lasers are sources of pulsed monochromatic UV radiation with a variety of interesting wavelengths and high output peak powers. However, they cannot compete with mercury arc lamps in large areas or fast-cure applications because of their low pulse repetition rates.9... 

N2 Uses monochromatic UV radiation to ionise molecules of organic compounds. The ions formed are 100 1000... 

Modern commercial lasers can produce intense beams of monochromatic, coherent radiation. The whole of the UV/visible/IR spectral range is accessible by suitable choice of laser. In mass spectrometry, this light can be used to cause ablation, direct ionization, and indirect ionization (MALDI). Ablation (often together with a secondary ionization mode) and MALDI are particularly important for examining complex, intractable solids and large polar biomolecules, respectively. 

Ito, T. Ito, A. Hieda, K. Kobayashi, K. Wavelength dependence of inactivation and membrane damage to Saccharomyces cerevisiae cells by monochromatic synchrotron vacuum-uv radiation (145-190 nm). Radiat Res. 1983, 96 (3), 532-548. 

In contrast, previous studies with LP Hg lamps indicated that a very high UV fluence Hq of up to 8000 mJ cm is required to inactivate Cryptosporidium. This observation was initially assigned to the much lower irradiance E of LP Hg lamps compared with that of MP Hg lamps or to wavelength effects (Bukhari et al, 1999). LP Hg lamps can be treated as being almost monochromatic UV-C sources ( max= 253.7 nm) whereas MP Hg lamps emit polychromatic radiation in the germicidal range between 200 and 300 nm (cf Fig.s 4-5 and 4-6). 

The carbon lamp is an intense source of monochromatic UV (193.1 nm) radiation (W4). Other monochromatic light sources can be constructed for a limited range of wavelengths by exciting the resonance emission of an atomic vapor (S24). These have a stable wavelength but the emission is unstable. Lasers provide high intensity monochromatic radiation for a number of wavelengths but they are of limited value in absorption spectrophotometry. 

For normal fluorescence scanning, a high-intensity xenon continuum source or a mercury vapor hne source is used, and a cutoff Alter is placed between the plate and detector to block the exciting UV radiation and transmit the visible emitted fluorescence. For fluorescence measurement in the reversed-beam mode, a monochromatic Alter is placed between the source and plate and the monochromator between the plate and detector. In this mode, the monochromator selects the emission wavelength, rather than the excitation wavelength as in the normal mode. 

Radiation per unit area for which the wavelengths of the monochromatic components are shorter than those for visible radiation. Note There are some variations in quantitative definition of UV radiation, for example, between 100 nm and 400 nm between 315 nm and 400 nm between 280 nm and 315 nm between 100 nm and 280 nm. 

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