Rotating sectored disk

On a more absolute level, a blackbody cavity surrounded by gold at its melting point (1064.43°C) can be focused upon for one calibration datum. Such a cavity is depicted in Figure 8.8. By placing a rotating sectored disk, or varying thicknesses of... 

Rotating sector disks also are frequently used in emission spectroscopy. The three principal types of rotating sectors are shown in Figure 5-5. The sector disk, illustrated in Figure 5-5A, has a variable aperture and is used to reduce the intensity of exposure. The sector disk is mounted in the optical path in front of the entrance slit to the spectrometer and is rotated at a constant rate. 

Experimental diffraction patterns of benzene recorded (a) without and (b) with a rotating sector. (We thank Christian Reuter, Bielefeld, for performing the experiments and preparing the figures.) (c) The shape of a rotating sector with the opening angle a dependent on the distance r from the center of the disk. 

Disk Filters A disk filter is a vacuum filter consisting of a number of vertical disks attached at intervals on a continuously rotating horizontal hollow central shaft (Fig. 18-127). Rotation is by a gear drive. Each disk consists of 10 to 30 sectors of metal, plastic, or wood, ribbed on both sides to support a filter cloth and provide drainage via an outlet nipple into the central shaft. Each sector may be replaced individually. The filter medium is usually a cloth bag slipped over the sectors and sealed to the discharge nipple. For some heavy-duty applications on ores, stainless-steel screens may be used. 

One of the simplest and earliest methods for the measurement of decay times was due to Becquerel (58). His instrument consisted of two disks mounted concentrically on a rotating shaft. Each disk contains a slit, or sector, cut into the circumference, and the sample to be studied is placed between the disks. The slits act as two shutters. The first opens to illuminate the sample, and the second permits the fluorescent light to exit to a detector. 

Sector mirror A disk with portions that are partially mirrored and partially nonreflecting when rotated, directs radiation from the monochromator of a double-beam spectrophotometer alternately through the sample and the reference cells. 

The light and dark periods are alternated using a rotating disk with slits (sectors). 

The experiment is performed as follows (Fig. 13.1). The reaction mixture is placed in a thermostatted vessel 6 with transparent planar-parallel walls. The vessel is irradiated with the light with such a wavelength that generates radicals. Disk 4 is placed in the point where the beams are focused and is rotated. The reaction rate is measured by this or another method from experiment to experiment, and the empirical dependence of the v/v ratio on logrj is plotted, td is found from the rotation velocity of the disk and the ratio between the sizes of the dark and light sectors (usually r - 3). This empirical dependence is compared with the theoretical one, and 2k, is determined by comparison, and from this 2k, is calculated. The initiation rate is measured by the methods of inhibitors (see above) or through the chain reaction rate and the kp/2k, ratio. 

Scheme of the sector installation /, light source 2, diaphragms 3, lenses 4, rotating disk 5, filter 6, reaction cell 7, photomultiplier and 8, thermostat. 

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