ABSTRACT
The thermoluminescent properties of crystalline uracil (U), and its halogen-substituted derivatives, 5 bromo-uracil (5BrU), 5 fluorouracil (5FU) and 5 iodo-uracil (5IU), have been investigated. The X-ray-induced thermoluminescent output increases in the order U less than 5 FU less than 5BrU less than 5IU. However, a reversed relationship is found for the U.V.-stimulated thermoluminescence. The thermoluminescence-emission spectra suggest that the same de-excitation process operates in all the halogen-substituted uracils, but the glow curves show that the charge-trapping characteristics are different for each material.
Subject(s)
Uracil/analogs & derivatives , Bromouracil/radiation effects , Fluorouracil/radiation effects , Freezing , Hot Temperature , Luminescent Measurements , Radiation Effects , Ultraviolet Rays , Uracil/radiation effects , X-RaysSubject(s)
Bone and Bones , Dental Enamel , Dentin , Luminescent Measurements , Animals , Calcification, Physiologic , Fossils , Hot Temperature , Humans , Hydroxyapatites , Methods , Rats , Spectrophotometry, Infrared , WhalesABSTRACT
An automated scanning spectroradiometer has been constructed for the measurement of color-vision test stimuli and various types of luminescence. A Jarrell-Ash 0.25-n, f/3.6 Ebert type monochromator is employed in combination with photoelectric detection. Recorder and paper tape data output have been provided. Processing of the spectral information is performed by a CDC 3300 computer. The spectral sweep range can easily be set by electromechanical registers, as can the number of required sweeps. Photon numbers are integrated by the counter over 5-nm blocks, and this procedure sets the limit of resolution. The spectral range is between 250 nm and 800 nm. By computer several spectra can be added when they are faint. Mean spectra are listed and plotted. Smoothing can be performed for spectra where noise is predominant. A novel method of correction by computer has been introduced to get rid of stray-light and grating ghosts in the monochromator. A program has been written for colorimetric analyses of light sources, spectral filters, and pigmented surfaces. The dominant wavelength and the excitation purity are computed and given in CIE chromaticity coordinates.
Subject(s)
Autoradiography/standards , Luminescent Measurements , Acrylates , Carbon Isotopes , Electrons , Plastics , Temperature , TritiumABSTRACT
Ceramic panelescent lamps of different colors have been investigated and calibrated as standard light sources for testing of potomultiplier equipment. Intensity and spectrum changes with voltage, frequency, and temperature have been studied. Inhomogeneities in the surface brightness have also been investigated. By use of a stabilized power supply very stable sources are obtained. For long term stability the most critical parameter is the working temperature of the lamp.
