Phosphor screen

Compounds that are radioactive can be located on a preparative layer by contact film autoradiography, electronic autoradiography, and storage phosphor screen imaging [21-23]. These methods differ in terms of factors such as simplicity, speed, sensitivity, and resolution, and the method of choice depends on the available equipment, reagents, and instrumentation. All are nondestructive, and the detected compounds can be recovered without change for later studies. 

A phosphor screen can be used like an autoradiography film to detect radioactive zones on PLC plates. The available screens are sensitive to x-rays and beta and gamma emissions from isotopes such as H, bij 32p 33p -pjjg screen captures... 

Muller (1951, 1956) developed this instrument, which for the first time enabled extensive details of the atomic structure of a solid surface to be seen directly. Figure 1.1 illustrates schematically the basic construction of a FIM. The specimen is prepared in the form of a fine wire or needle, which has been chemically or electrochemically polished to a sharp point with an end radius typically 50-100 nm. It is mounted along the axis of a vacuum chamber, about 50 mm from a phosphor screen (perhaps 75 mm in diameter). The specimen is mounted on an electrical insulator within a cryostat, and it can be raised to a high positive potential (3-30 kV) by means of the leads attached. 

Fig. 1. Schematic diagram of the multimass ion imaging detection system. (1) Pulsed nozzle (2) skimmers (3) molecular beam (4) photolysis laser beam (5) VUV laser beam, which is perpendicular to the plane of this figure (6) ion extraction plate floated on V0 with pulsed voltage variable from 3000 to 4600 V (7) ion extraction plate with voltage Va (8) outer concentric cylindrical electrode (9) inner concentric cylindrical electrode (10) simulation ion trajectory of m/e = 16 (11) simulation ion trajectory of rri/e = 14 (12) simulation ion trajectory of m/e = 12 (13) 30 (im diameter tungsten wire (14) 8 x 10cm metal mesh with voltage V0] (15) sstack multichannel plates and phosphor screen. In the two-dimensional detector, the V-axis is the mass axis, and V-axis (perpendicular to the plane of this figure) is the velocity axis (16) CCD camera.

Thorn EMI 9235QB) near the phosphor screen to collect all of the ion signal as the probe laser was tuned over the 0(3Pj) Doppler profile at laser wavelengths of 226.23, 226.06 and 225.65 nm for j = 0, 1 and 2, respectively. The output of the photomultiplier was sent to a boxcar averager gated at the appropriate arrival time. The probe laser power was simultaneously measured with a photodiode in order to normalize the 0(3Pj) signal intensity for fluctuations in laser power. 

Phosphors for CRTs are predominantly based on zinc and cadmium sulfides. Selected CRT phosphors are listed in Table 1 which also includes their precursors, their P-numbers , and their uses. (The system used to classify CRT phosphors came from JEDEC, the former Joint Electronic Device Engineering Council, now JT- Committee on Phosphor and Optical Characteristics within the Electronic Industries Association. JEDEC established the original code for these phosphors in terms of P-numbers .8 Many manufacturers of CRTs use these when specifying phosphor screen characteristics.) Although the precursors are tabulated, the mole ratios used in the syntheses are not. 

Penetration-phosphor screen . Blue and yellow-green-emitting phosphors... 

Deep blue-emitting (centered at 415 nm) phosphor screen used wherever a very fast decay is needed, such as flying spot scanners... 

Laser devices are the most sophisticated image-acquisition tools. They are particularly useful for gels labeled with fluorescent dyes because the lasers can be matched to the excitation wavelengths of the fluorophores. Detection is generally with photomultiplier tubes. Some instruments incorporate storage phosphor screens for detection of radiolabeled and chemiluminescent compounds (not discussed in this chapter). Resolution depends on the scanning speed of the illumination module and can be as low as 10 pm. 

The accelerating voltage in a streak camera is set to 500 V. If the distance between the electrodes used for electron deviations is 15 cm and the applied voltage between these electrodes is 1200 V, calculate the maximum spatial deviation that can be induced in the phosphor screen if the distance between the photocathode and the phosphor screen is 30 cm. 

Mn + ions (3d electronic configuration) are shown to produce a broad luminescence in more than 500 inorganic compounds, covering a wavelength range from about 490 nm to about 750 nm. Although this ion is not of relevance for laser applications, it is widely used in the phosphor screens of cathode ray tubes and in fluorescent lamps. 

The large rocking curve width associated with the extended source makes it easy to set up the Berg-Barrett topograph. This can be done with a counter but is most easily achieved with a phosphor screen and TV camera. The strength of the beams is such that only modest gain is needed and the equipment can therefore... 

Indirect conversion devices have been reported with comparable spatial resolution 13 based on a thin fluorescent screen in the form of a microscope objective lens. This again has a small field of view and poor efficiency owing to the low stopping power of the phosphor screen. Commercial devices based on a charmel plate intensifier coupled to a CCD camera usually give a spatial resolution of about 25 /an, which is adeqrrate for many industrial applications where screening of substrates is reqrrired. However, only slow progress has been... 

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