Ultraviolet source

Hahde complexes of Cu with nitrogen base ligands are known to exhibit another form of reversible spectral change known as fluorescence thermochromism. The example of Cu4l4(Py)4 from Table 1 is typical and shows red shifting ia the visible emission spectmm while the sample is both cooled and irradiated with a 364 nm ultraviolet source (7). 

Ever brighter vacuum-ultraviolet sources are being developed that would further boost SPI sensitivity, which already is typically 10 useful yield general, sensitive elemental analysis would then also be available using SPI, making possible a single laser arrangement for both elemental and molecular SALE... 

In luminescent microscope, light from the ultraviolet source (UV source) excites the fluorescence of the object, the luminescent image might be catched... 

The word monochromator is derived from the Latin language, mono meaning one and chromo meaning color. It is a device more sophisticated than an absorption filter that isolates the narrow band of wavelengths from visible and ultraviolet sources. 

The usual sources of ultraviolet radiation are hydrogen or deuterium discharge lamps (the latter usually being preferred) or the mercury vapour lamp. All ultraviolet sources must be fitted with quartz or silica glass windows and none of the lamps named emits any significant amounts of radiation above 400 nm. 

H. Schnitzler, U. Frohlich, T.K.W. Boley, A.E.M. Clemen, J. Mlynek, A. Peters, and S. Schiller, All-solid-state tunable continuous-wave ultraviolet source with high purity and frequency stability. Applied Optics 41(33), 7000-7005 (2002). 

Photolysis Reactors and Ultraviolet Sources. For 253.7-m/ irradiation, a modified irradiation apparatus purchased from Delmar Co. was used. The reactor was a 2-necked, 500-ml., round-bottomed flask. One neck was an O-ring joint, and the other was a 24/40 joint. A 4- X 1-inch coiled low pressure mercury quartz lamp was placed inside the flask through the O-ring neck, and the joint was sealed with removable O-rings. The reactor was connected directly to the mass spectrometer by the 24/40 joint. The samples were placed inside the flask and irradiated internally. The O-ring was shielded from direct radiation so as not to induce degradation. The estimated output of the lamp was 30 watts, and the ambient temperature within the reactor during irradiation was 70°C. 

Samples were irradiated in the following manner Cellulose triacetate, 2- X 2-inch film, was placed under the ultraviolet source for irradiation. The monomeric compounds were dissolved in suitable solvents and slurried along the reactor walls. Residual solvent was removed under... 

Ultraviolet sources are chiefly mercury-discharge lamps in various forms. These lamps are fragile and quite inefficient. The design of reactors using these lamps is hampered by these considerations, and by the limited ultraviolet transmission, of common glasses and solvents. The transmission is further decreased by coatings of opaque materials which form... 

The power levels of radioactive sources presently available are comparable to the output of the most intense discharge lamps available. Ultraviolet sources produce 10 to 100 w. of useful ultraviolet radiation. Kilocurie sources of 2 Mev. activity produce approximately 20 w. The total available power from such a source having a half-life of 10 years is an order of magnitude lower than the total power output available from an ultraviolet lamp operating for 1000 hours, the normal expectancy for lamps of this type. 

Ultraviolet radiation is harmful to the naked eye. Do not view an ultraviolet source without protection. 

A photoionization detector uses a vacuum ultraviolet source to ionize aromatic and unsaturated compounds, with little response to saturated hydrocarbons or halocarbons. Electrons produced by the ionization are collected and measured. 

Figure 1 shows the activation spectrum of polystyrene measured by Hirt and co-workers (8). It represents the yellowing, as measured by the increase in absorbance at 4000 A., caused by the various wavelengths of ultraviolet radiation between 2800 and 4000 A. The ultraviolet source used for these measurements was a xenon arc equipped with a borosilicate... 

Boyd IW, Zhang J-Y, Bergonzo P (1995) New excimer ultraviolet sources for photo-assisted deposition of thin films an alternative to excimer laser-induced deposition, Proc. SPIE-Int. Soc. Opt. Eng. 2403 290-301. 

Zhang J-Y, Boyd IW (1998) Efficient Xel Excimer Ultraviolet Sources from Dielectric Barrier Discharge, J. Appl. Phys. 84 1174-1178. 

Excess irifluoroiodomethane (2mL) was condensed into a 5-mL flask containing (EtO)jP (I 1.93 g, 12 mmol, freshly distilled from Na metal). The mixture was irradiated for 10 h with a Black-Ray Long Wavelength Ultraviolet source (350.0 nin). After evaporation of unreacted trifluoroiodomethane and tri-Ouoromethane byproduct, distillation of the remaining residue gave diethyl trifluorometliyl phosplionate (5) yield 1.2 g (51 %) bp 65-67.5 C/8 Torr. 

Photolysis of the quinoline Reissert compound (7) showed a marked dependence on the wavelength of the ultraviolet source. With 2537 A light in acetonitrile an 8 % yield of 2-cyanoquinoline and a trace of... 

Results + + + denotes very strongly positive + + denotes strongly positive + denotes faintly positive test length of inhibition period depends on distance of ultraviolet source and H202 concentrations... 

The checker notes that the technique given here for purification of the Fe(HPDM)CIis unsatisfactory for the purification of Fe(TPP)Cl, since free TPPand the/t-oxo dimer do not separate sharply. If, however, the crude reaction mixture is followed on the column by the use of a long-wave ultraviolet source under darkened conditions, the free-base TPP front can be sharply separated from the trailing g-oxo smear and thus satisfactorily separated. 

The relative spectral power distribution of Abbreviation-. UV, ultraviolet. Source-. From Ref. 10. 

Figure 10 Illustration of the relationship between pulse height, pulse width, number of pulses and heat generated in a UV exposure. Abbreviation UV, ultraviolet. Source Reproduced with permission from the Xenon Corporation.

Figure 7 Typical surface temperature profile for colored samples exposed to outdoor sunlight (45° south facing-backed exposure), xenon long-arc radiation (intensity set to 0.55 W/m2 at 340 nm, filtered to mimic outdoor sunlight), and a fluorescent UVA-340 lamp. Abbrevlatlorr. UV, ultraviolet. Source Courtesy of Atlas Materials Testing Technology, LLC, Chicago, IL, U.S.A.

The efficiency of the exposure source is a critical cost and thruput factor. Ultraviolet sources output up to 10% of the input energy while 150 KV electron cure sources can be 70% efficient. To record high... 

Photoionization time-of-flight mass spectrometry is used almost exclusively in all experiments described in this review. The ionizing laser sources have included excimer lasers for photon energies up to 7.87 eV and tunable ultraviolet sources up to 6.5 eV. In some early studies, multiphoton ionization was used, but it has become quite clear that this usually results in dissociative ionization. Such effects have been observed in many systems, ranging from Si49,5o ( 51 jQ jjjg transition metals. Thus single-photon ionization has... 

---