Lamp, free running

The free-running mode has an internal clock generator that periodically triggers the flash lamp. For long-duration degradation experiments, it is important that the irradiation lamp intensity reaching the measurement cell, MC, remains constant. 

Figure 3.10 Output from a free-running high-gain Laser, pumped by a pulsed excitation Light source (flash Lamp or Laser)...

UV irradiation of a dry benzene soln (120 mL) containing 1,1-diarylethene (0.40-0.05 mol) and diphenyldiazomethane (0.15-0.076 mol) was carried out in an immersion-type irradiation vessel equipped with a mercury high-pressure lamp (Philips, HP 125 W) surrounded by a quartz water jacket. The solution was purged with Oj-free Nj for 15 min prior to the photochemical reaction, which was run under dry Nj. Irradiation, performed at 13 °C, lasted for about 15-30 h. The workup procedure consisted of removal of benzene followed in some cases by column chromatography (50 cm) of the oily product on acidic alumina with various solvents and recrystallization of the colorless crystals from EtOH. 

Hanst and Calvert (1959) showed from product analysis that the primary process in CH3ONO photolysis at wavelengths >310 run from a mercury lamp could be explained by O-N bond cleavage, Eq. la. By doing experiments in the absence and presence of large amounts of O2, they were able to show that there was no formation of CH3 + NOj, CH3 + NO + O, or CH3ON + O. This was deduced fiom the fact that the products expected from these free radicals... 

The SiOx films we fabricated was done by physical vapor deposition of SiO with controlled oxygen admission in an oil-free vacuum apparatus at 1 x 10 mbar base pressure. The experimental set-up is shown schematically in Figure 19.4. Thermal evaporation of SiO from two Ta boats was directed to rotating 10 cm Si(lOO) wafer substrates heated by rear illumination with tungsten halide lamps. To achieve uniform film thickness over the large area of the Si wafer, the angle between the evaporators and substrate center was fixed at 53°, while the distance between the substrate plane and evaporator plane was kept at 20 cm. Routinely, films of 100 run... 

If the HCL is run at a high current, an abundance of free atoms form. These free atoms absorb at precisely the resonance lines the hollow cathode is intended to emit an example is shown in Figure 6.28, with the free atoms absorbing exactly at K over an extremely narrow bandwidth (Figure 6.28b). The result is that the line emitted from the HCL is as depicted in Figure 6.28c instead of the desired emission line depicted in Figure 6.28a. The emitted lines are broadened by the mechanisms discussed in Section 6.1.1. The phenomenon of absorption of the central portion of the emission line by free atoms in the lamp is called self-reversal. Such absorption is not easily... 

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