Radiation-induced Coloration Research Articles

Radiation-induced coloration of xylenol blue/film containing hexachloroethane for food irradiation applications

Polyvinyl butyral films mixed with xylenol blue (XB) indicator and hexachloroethane (HCE) were prepared for possible application in food irradiation. Upon γ–irradiation the films undergo visual color change from yellow (XB, pH 8) to red (XB, pH 2.8) by H+ formation in the presence of HCE. The dosimetric characteristics of films containing different dye and HCE concentrations were investigated spectrophotometrically at λmax 555 nm. Radiation sensitivity is enhanced with HCE and, accordingly red color intensity. The prepared films can be applicable in dose range 0.25–10 kGy with uncertainty of dose reaching 4.45 % at 1σ.

Spectroscopic investigation of gamma radiation-induced coloration in silicate glass for nuclear applications

Silicate glass irradiated by γ-rays was investigated in this study using spectroscopic analyses which included ultraviolet–visible (UV–Vis) absorption, electron paramagnetic resonance (EPR), and nuclear magnetic resonance (NMR). The phenomenon of coloration on γ-ray-irradiated silicate glass was analyzed and the effect of annealing on the silicate coloration was also investigated. The results revealed that the coloration originates from the creation of hole-centers (HC) caused by radiation. The shade of the coloration highly correlates to the amount of these HC-related defects but can be reversed by thermal annealing. The variation in coloration is an effective predictive factor in understanding radiation damage on silicate glass. Therefore, this study is relevant in the development of radiation detectors using silicate material as well as in the permanent disposal of high-level nuclear waste in glass form.

Effect of additive ions on the optical density and stability of the color centers induced by X-ray irradiation in soda-lime silicate glass

To apply radiation-induced coloration of glasses as a reversible glass-coloring technique, we studied the influence of various additive ions incorporated into a soda-lime silicate glass on the optical density and stability of the color induced by X-ray irradiation. Absorption spectra before and after irradiation are discussed in the comparison with those of the undoped soda-lime silicate glass. Additive ions were incorporated as metal oxides, namely TiO 2, V 2O 5, Fe 2O 3, ZnO, Ga 2O 3, GeO 2, ZrO 2, Nb 2O 3, MoO 3, Ag 2O, In 2O 3, SnO, SnO 2, CeO 2, Eu 2O 3, Ta 2O 5, WO 3 and Bi 2O 3. Among them, TiO 2, GeO 2, Nb 2O 3, MoO 3, Ag 2O, In 2O 3, Eu 2O 3, Ta 2O 5, WO 3 and Bi 2O 3 have a large effect on optical density. The optical densities in the visible region for glasses doped with these oxides were much stronger than for undoped soda-lime silicate glass. On the other hand, incorporation of Fe 2O 3, SnO and CeO 2 reduced the optical density. Over longer periods the coloration of the undoped glass was one of the most stable while those of the Fe 2O 3, SnO and CeO 2-doped glasses soon faded.

Recovery of radiation-induced coloration on various polyimides

The polyimide films are colored by radiation exposure. The color of irradiated films, however, fades with the exposure time in air. This discoloration obscures the accurate evaluation of degradation in ground-simulation tests. Therefore, we experimentally clarified the discoloration behaviors for the post-irradiation sample in air. There was a difference in the time constant of air recovery among the three types of polyimides. The recovery behavior depended on the type and thickness of the polyimide. In addition to these, it would be deduced that the behavior of color fading depends on the uniformity of degradation. If the coloration immediately after irradiation is needed to evaluate the degradation, it is necessary to know the recovery behavior on each type and thickness of polymer because the order of radiation resistance varies depending upon the length of time that has elapsed since the air exposure of irradiated sample.

The Radiation-Induced Coloration of Dithienylethene Amorphous Films

ABSTRACT The radiation-induced coloration of bulk amorphous films of five photochromic diarylethenes was studied with the aim of developing reusable, sensitive color dosimeters. Although amorphous films of bisbenzothienylentene derivatives 3 , 4 and 5 exhibited only weak coloration upon γ-irradiation, intense coloration was observed for the film containing 1,2-bis(2,4-dimethyl-3-thienyl)perfluorocyclopentene 1 having diphenylphenyl substituents. The color was stable in the dark, but disappeared upon irradiation with visible light. The sensitivity remained at 80% of the initial value even after 10 cycles.

The Radiation-Induced Coloration of Amorphous Photochromic Dithienylethene Films

Abstract The radiation-induced coloration of bulk amorphous films of five photochromic diarylethenes was studied with the aim of developing reusable, sensitive color dosimeters. The films contain an extremely high concentration of diarylethenes. The most intense coloration was observed for the film containing 1,2-bis(2,4-dimethyl-3-thienyl)perfluorocyclopentene having 3-phenyl-4-diphenylyl substituents. The color disappeared upon irradiation with visible light. The coloration increased linearly with an increase in the absorbed dose up to 3000 Gy. The relative sensitivity of radiation-induced coloration among the five derivatives qualitatively agreed with the sensitivity of photo-induced coloration from UV light (254 nm) irradiation.

Effect of Temperature on the Relaxation of Radiation-Induced Coloration in Optical Glasses

Optical and radiation-resistant crown and flint glasses exposed to gamma irradiation at room temperature are investigated. The relaxation of radiation-induced absorption in irradiated glasses is examined prior to and after short-term or long-term heat treatment at different temperatures in the range 20–150°C. It is established that an increase in the heat treatment temperature by even several tens of degrees leads to a drastic increase in the relaxation rate of radiation-induced coloration and a decrease in the time of complete bleaching of irradiated glasses by several orders of magnitude.

The Effect of Additives on the Radiation-Induced Coloration of Photochromic Dithienylethene Derivatives

Abstract The effect of the addition of metal complexes and aromatic compounds on the radiation-induced coloration of polystyrene films containing 1,2-bis(2-methyl-5-phenyl-3-thienyl)perfluorocyclopentene was examined to develop a sensitive reusable color plastic dosimeter. By the addition of metal complexes, the radiation sensitivity increased along with an increase in the atomic numbers. When aromatic compounds, such as naphthalene, biphenyl, and acenaphthene, were added to the polymer film, the coloration sensitivity increased, while the addition of anthracene and pyrene decreased the sensitivity. Excitation energy transfer from the sensitizers to the dithienylethene is considered to play an important role in the radiation-induced coloration in polystyrene films containing the additives.

Radiation-Induced Coloration of Photochromic Dithienylethene Derivatives in Polymer Matrices

Abstract The high-energy radiation-induced coloration of photochromic dithienylethenes was studied in various polymer matrices with the aim of developing a reusable color plastic dosimeter. Upon γ-irradiation, polystyrene films containing 1,2-bis(2,5-dimethyl-3-thienyl)perfluorocyclopentene 1a and 1,2-bis(2-methyl-5-phenyl-3-thienyl)perfluorocyclopentene 2a turned red and blue, respectively. The red and blue colors disappeared upon irradiation with visible light, and the films could be reused. In both films the absorption intensities of the colors increased linearly with the absorbed dose. Although radiation-induced coloration was clearly detected in polystyrene films, a color change was scarcely observed in poly(methyl methacrylate) (PMMA) and poly(N-vinyl carbazole) containing 1a and 2a. Excitation energy transfer from polymers to dithienylethenes is considered to play a role in the coloration process in polymer films.

Radiation-Induced Coloration of Photochromic Dithienylethene Derivatives

Abstract The radiation sensitivity of photochromic 1,2-dithienylethenes was studied with the aim to develop a new reusable color dosimeter. Upon γ-irradiation, crystalline colorless 1,2-bis(2,5-dimethyl-3-thienyl)perfluorocyclopentene turned red, and the absorption intensity increased linearly with the absorbed dose. The red color was bleached by visible-light irradiation and the crystal could be reused. On the other hand, crystalline 1,2-bis(2-methyl-1-benzothiophen-3-yl)perfluorocyclopentene did not show any radiation-induced coloration. The radiation sensitivity in solution was also examined to understand the possible applications to solution and film color dosimeters. Although radiation-induced coloration of the above two compounds was observed in benzene, no color change was detected in hexane, 2-methyltetrahydrofuran and n-butyl chloride. Excitation energy migration and transfer mechanism is considered to play a role in the coloration process in benzene.

Colour Centres in LiF for Measurement of Absorbed Doses up to 100 MGy

Radiation damage studies on electronic components, polymers, composites, ceramics, metals, and insulating materials exposed to very large doses of ionising photons and particles (i.e. electrons, protons, and neutrons) require reproducible and accurate passive dosimetry. Absorbed doses in the range 10 2 -2 x 10 6 Gy have previously been measured with optical quality, undoped LiF by spectrophotometry of radiation-induced absorption bands of stable colour centres. These include the relatively stable F centre (247 nm), M centre (443 nm), R 1 centre (315 nm), R 2 centre (374 nm), and N 2 centre (547 nm). It is now possible to extend this range to 10 8 Gy by spectrophotometry of the N 1 centre (517 nm) and an 'X' centre (785 nm). These dosemeters can be used from cryogenic (4 K) to relatively high radiation temperatures (up to 500 K). The radiation-induced coloration can be bleached for re-use of the dosemeters by a two hour thermal annealing treatment at 830 K.

Studies on the radiation-induced coloration mechanism of the cellulose triacetate film dosimeter

The species responsible for the coloration of the cellulose triacetate (CTA) film dosimeter have been studied using ultraviolet, electron spin resonance, infrared and gas chromatographic techniques. The post-irradiation change in the optical density at 280 nm indicates that the coloration occurs not only during irradiation ( in situ coloration) but also after irradiation (post-irradiation coloration) and that in situ coloration is due to unstable and stable components. The species responsible for the unstable component of in situ coloration are ascribed to the radicals produced from CTA molecules and those for the stable component to the radiolysis products from CTA and triphenyl phosphate contained in the dosimeter. On the other hand, post-irradiation coloration is attributed to the formation of carbonyl groups in CTA molecules, which is induced by reaction with NO 2 produced by irradiation of air.

Effect of temperature on radiation-induced coloration of detectors based on thallium-activated sodium iodate crystals

Effect of temperature on radiation-induced coloration of detectors based on thallium-activated sodium iodate crystals

Radiation-induced coloration in KBr crystals subjected to AC electric fields

Optical absorption and thermoluminescence (TL) output measurements were made on KBr single crystals treated in a high alternating (50 Hz) electric field and irradiated with X-rays at room temperature. A substantial enhancement of both the F-centre concentration and the thermoluminescence light output was observed in AC field treated samples upon X-irradiation. The effect of AC field treatment on the F-centre growth curves is also reported.

Effects of temperature on cobalt glass dosimeters.

The effects of temperature upon the radiation-induced absorbance spectra of cobalt borosilicate glass dosimeters were investigated by subjecting dosimeters to different combinations of preexposure, exposure, and post exposure temperature environments. The dosimeters were exposed to 2 × 104, 105, 5 × 105 and 106R in a 60Co irradiator, and absorbance measurements were taken at 3000 A, 3750 A and 5000 A over a four month study period. No significant difference in absorbance was produced by exposure temperatures within a 0°C to 100°C range, but exposure temperatures beyond 150°C resulted in decreases in absorbance levels. The radiation-induced coloration faded linearly with the logarithm of time following exposure with the fading rates being dependent upon exposure, exposure temperature, storage temperature, and the wavelength at which the absorbance spectra were measured. The coloration was completely removed by a 1 hr heat treatment at 500°C. This clarification treatment did not affect the radiation response of the dosimeters given subsequent exposures.

F-center accumulation in filar KCl crystals irradiated with X-rays

The article outlines research on the kinetics of F-center accumulation in filar KCl crystals of various diameters and various origins. The mechanism of dislocation-group formation and the crystal surface cannot account for the radiation-induced coloration of alkali-halide crystals at room temperature. Differences in the properties of filar crystals grown by various techniques were observed for the first time.

Mechanism of radiation-induced coloration of NaCl crystals

Mechanism of radiation-induced coloration of NaCl crystals

Gamma-Induced Absorption and Structural Studies of Arsenic Borate Glasses

Gamma-induced coloration in borate glasses containing arsenic was studied to secure information on: (a) the effect of addition of As2O3 on the induced coloration of the alkali borate base glass, and (b) the possibility of using radiation-induced coloration in studying structural changes. At concentrations of less than 10 mole % As2O3, arsenic takes network-modifying positions and at concentrations greater than 10.0 mole % As2O3, it takes network-forming positions. Between 15.0 and 25.0 mole % As2O3, an additional change in the structure was detected. This change may be confined to the mode of arrangement of the structural units associated with the formation of groups or compounds. Additional studies based on infrared absorption, ultraviolet absorption edge, and density measurements, as well as the chemical analysis of the glasses, confirmed the structural changes suggested from irradiation studies.

Gamma‐Ray‐Induced Coloration in Solids; Application to Glass Systems

General aspects of radiation‐induced coloration in solids are discussed. It is considered that the most significant initial effect of the radiation is to produce free electrons and trapped holes in a track. The decay of the track from the initial condition is described in some detail, assuming (a) that the rate of diffusion of electrons from the track is small compared with the rates of other processes and (b) that primary processes which form color centers can be considered to be independent of secondary processes which cause destruction of color centers. A method of calculation is described which gives the concentration of color centers formed at various doses. With plausible assumptions for the parameters, agreement with the data of Schulman et al. on a silver phosphate glass is obtained. The treatment of glasses less simple than the silver phosphate glass is also discussed.

Glass dosimetry of soft x rays.

The results of an investigation of the radiation-induced coloration of commercially available microscope glass coverslips as a dosimetric system for 35 keV X rays are given. A dose range of 1·5 × 103 to 1·4 × 107 r has been used. Special attention has been paid to correction for fading during and after the exposure. A mathematical interpretation of the calibration curves is arrived at.