DEPENDENCE OF THE OPTICAL BLEACHING RATE OF X-IRRADIATED KCI CRYSTALS ON LIGHT INTENSITY

Journal Article · Thu Sep 15 04:00:00 EDT 1960 · Physical Review (U.S.) Superseded in part by Phys. Rev. A, Phys. Rev. B: Solid State, Phys. Rev. C, and Phys. Rev. D

DOI:https://doi.org/10.1103/PhysRev.119.1864· OSTI ID:4148028

Bron, W E; Heller, W R

Measurements were made on the changes in the bleaching rate of the F band as the result of varying the intensity of F light. Bleaching was done on KCl crystals that were irradiated at room temperature with hard x rays into either the first or second stage of coloration. In the first stage irradiated crystals, the total bleaching of the F centers during the first ten seconds of illumination varied approximately linearly with light intensity at low intensities but became saturated at intensities greater than 5 x 10/sup 14/ photons/sec cm/sup 2/. The bleaching process was thought to occur primarily through the capture of photoelectrons at pre-existing electron traps. Based on this model it was possible to set up the kinetic equations for the bleaching process. Using reasonable values for photoelectron capture coefficients forced the conclusion that the number of photoelectrons war always very small throughout the bleaching process. The resulting simplification in the analysis of the kinetic equations led to a prediction of the experimentally observed variation of the initial bleaching rate with light intensity. The analysis showed that the ratio of the capture coefficient for photoelectrons of the electron trapping centers to that of negative-ion vacancies was about unity, which strongly suggested that the trapping centers were either traps with net positive charge or were neutral traps located close to the original F centers. The rate of bleaching during the second stage of bleaching saturated at the lowest intensity used, which was about 1 x 1O/sup 14/ photons/sec cm/sup 2/. This result is discussed in terms of the analysis given for the first stage of bleaching. (auth)

• Research Organization: International Business Machines Research Center, Yorktown Heights, N.Y.
• NSA Number: NSA-14-024641
• OSTI ID: 4148028
• Journal Information: Physical Review (U.S.) Superseded in part by Phys. Rev. A, Phys. Rev. B: Solid State, Phys. Rev. C, and Phys. Rev. D, Journal Name: Physical Review (U.S.) Superseded in part by Phys. Rev. A, Phys. Rev. B: Solid State, Phys. Rev. C, and Phys. Rev. D Vol. Vol: 119; ISSN PHRVA
• Country of Publication: Country unknown/Code not available
• Language: English

Related Subjects

ABSORPTION
BLEACHING
CAPTURE
COLOR
CRYSTALS
DEFECTS
DISTRIBUTION
ELECTRIC CHARGES
ELECTRONS
F CENTERS
IONS
IRRADIATION
LATTICES
LIGHT
MATHEMATICS
MEASURED VALUES
MECHANICS
METALS, CERAMICS, AND OTHER MATERIALS
PHOTOELECTRIC EFFECT
PHOTONS
POTASSIUM CHLORIDES
RADIATION EFFECTS
SPECTRA
STABILITY
TRAPS
VACANCIES
X RADIATION