Cluster lamp

The latest type of incandescent lamp is the cluster lamp. A tungsten bromide vapor in a bulb is excited by a plasma with external electrodes. Light is emitted by 2-nm tungsten particles that form in the center of a plasma, where they reach a temperature of 3300°C. At a lower temperature near the bulb wall the particles react with bromine and form the gas that decomposes again at the higher temperatures in the plasma. 

If the size of the production unit requires higher radiant power than can be provided, for technical reasons, by one lamp, clusters of light sources may be installed, which, consequently will alter the diameter or the height of the inner core of, for example, an annular photochemical reactor. However, following the check list of concepts (vide supra), optimal reaction conditions will in most cases limit the size of the photochemical reactor, and the planned rate of production may require several reactor units installed in a parallel mode (batch process) or in series (continuous process). 

The reaction of 3,4-benzo-l,2-disilacyclobutene (22) with Cgo yields the corresponding disilacyclohexane derivative (23)20. Irradiation of a solution of disilacyclobutene 22 and Cgo in toluene with a low-pressure mercury lamp (254 nm) afforded the brown adduct 23 in 14% yield (based on unreacted Cgo) (equation 8). The FAB mass spectrum of 23 exhibits one peak at m/z 1024-1027 (C7sH32Si2, M+, molecular cluster ion), as well as one for Cgo at m/z 720-723. The -NMR spectrum of 23 showed a symmetrical spectrum with two diastereotopic isopropyl methyl protons, one isopropyl methine proton and a AA BB pattern assigned to phenyl protons. The 13C-NMR spectrum of 23 shows 17 signals for the Cgo skeleton, of which four correspond to two carbon atoms each and 13 correspond to four carbon atoms each one signal appears at 63.93 ppm and the remainder between 130 and 160 ppm (Scheme 7, Figure 10). This pattern is consistent... 

The photochemical reaction of bis(alkylidene)disilacyclobutane (24a and 24b) with C60 by a high-pressure mercury lamp (cutoff <300 nm) proceeds to afford the adducts 26a (61%) and 26b (52%) instead of 2521. The formation of these products is a result of an unexpected rearrangement of the disilacyclobutane moiety (equation 9). The FAB mass spectrum of 26a exhibits one peak at m/z 1056-1059 (CsoFUoSia, M++l cluster), as well as one for Q,o at m/z 720-723. 

Nishi and coworkers (Shinohara et al. 1985, 1986) have reported the production of unprotonated water and ammonia cluster ions, as well as Ar X+ (X = H20 and NH3) cluster ions when argon/molecule mixed expansions were ionized using UV lines from an argon lamp. The quenching of the proton transfer reaction was attributed to the cooling of the heterocluster ions via... 

Alternative procedures to obtain FePt nanoparticles use direct cluster deposition with a particle gun [37], Under normal conditions, the FePt clusters have the fee structure. In this original development, the particles passing through halogen lamps are annealed before deposition. The nanoparticles are embedded in a carbon matrix with typical size of 6 nm. /i0Hc = 0.3 T is obtained. 

The preparation of the supported catalytic Fe-clusters have been recently reported by our laboratory for Fe/Nafion membranes [1,2,3] for Fe/Nafion/glass-mats [4,5] micro-encapsulated Fe-alginate beads [6] Fe-amorphous polycrystalline thin film fused copolymers [7] and finally Fe/silica woven fabrics [8]. Experiments were conducted with Nafion perfluorinated cation transfer membrane. Photolysis experiments were carried out by means of a Hanau Suntest Lamp with tunable light intensity equipped with an IR filter to remove infrared radiation. Light... 

Hastie [131] coupled for the first time a quadrupole mass spectrometer with a Knudsen cell. One of the quadrupole mass spectrometer - Knudsen cell systems used at our laboratory is shown in Fig. 4. The system has been developed to study small alkali metal clusters under equilibrium conditions (see Sect. 3.2). Broad-band photoionization by a 1 kW Hg/Xe lamp is used for the first time in Knudsen effusion mass spectrometry to reduce fragmentation. Other quadrupole mass spectrometer - Knudsen cell systems have for example been developed by Hilpert [132, 133], Fraser and Rammensee [134], Plante [135], Ono et al. [136], Kematick et al. [137], and Edwards et al. [138]. Cryogenic pumping is used in the device by Hilpert to reduce mercury background ion intensities for the study of amalgams [132], The instruments described in Refs. 134,135 use a chopper to modulate the molecular beam from the Knudsen cell. Interfering background ion intensities can, thereby, be subtracted. The apparatus developed by the authors of Refs. 137, 138 renders possible the simultaneous application of Knudsen effusion mass spectrometry and the mass-... 

Uniform 1.5 pm thick PS layers were formed by anodization of p-type Si wafers of 0.3 Ohm em resistivity in 48% HE. After anodization, the HE electrolyte was replaced by a O.IM FeS04+0.001M EifNOals solution and a Fe Er film was electrochemically deposited into PS. As SIMS analysis showed, both Er and Fe can be introduced deeply into PS by this electrochemical technique [5], The maximum Er and Fe concentrations were estimated to be 0.1 and 10 at. %. The samples were oxidized at 500°C for 360 min and then at 1100°C for 15 min in O2 atmosphere. This treatment has been shown to form 5-50 nm iron/erbium oxide clusters inside OPS [5]. As comparison reference, Er-doped OPS containing Si clusters (without Fe) samples were fabricated in a similar way by polarization of PS in an Er(N03)3 solution. Photoluminescence excitation (PLE) spectra were recorded at 77 K by a grating spectrometer MDR-23 equipped with a Ge Cu detector. A Xe lamp was used as the excitation source. 

Figure 22.2. PL study of a sample produced by cluster beam deposition using a chopper for size separation. The upper panel shows a photo of the deposit when it was illuminated by a simple UV lamp. The lower panel reports the PL spectra recorded at the positions indicated by the arrows.

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