Free Access
Microsc. Microanal. Microstruct.
Volume 6, Number 1, February 1995
Page(s) 79 - 88
Microsc. Microanal. Microstruct. 6, 79-88 (1995)
DOI: 10.1051/mmm:1995108

Characterization of Double Structure Tabular Microcrystals of Silver Halide Emulsions by Means of Electron Energy-Loss Spectroscopy, Zero-Loss Electron Spectroscopic Imaging and Energy-dispersive X-ray Microanalysis

Vladimir Oleshko1, Renaat Gijbels1, Willem Jacob2, Frank Lakiere2, André Van Dele2, Eugeny Silaev3 et Lilia Kaplun3

1  Department of Chemistry, University of Antwerp (UIA), B-2610 Wilrijk-Antwerpen, Belgium
2  Department of Medicine, University of Antwerp (UIA), B-2610 Wilrijk-Antwerpen, Belgium
3  Research Institute for the Photographic Industry, 125167 Moscow, Russia

Electron energy-loss spectroscopy (EELS) and zero-loss electron spectroscopic imaging (ZLESI) in conjunction with spot energy-dispersive X-ray microanalysis (EDX) were applied to the structural and chemical characterization of practical emulsion core (AgBr)-shell ${\rm (AgBr}_{{\rm 1-}x}{\rm I}_x{\rm )}$ tabular microcrystals). The samples were cryocooled to minimize damage under the electron beam. Recorded energy-loss spectra of the crystals in the initial state and after a 2-minute development contained several low intensity bands, which were tentatively assigned to silver and halides, as well as bulk, surface and defect plasmons and interband transitions. Spatially resolved energy-loss spectra of silver specks on extractive carbon replicas of silver halide grains showed the presence of the delayed Ag $M_{{\rm 4,\ 5}}$-edge at 400 eV. Results of EELS-microanalysis have been confirmed by EDX spot analysis of the same emulsion samples. The improved contrast in the ZLESI mode enabled the detection of dislocation grid and stacking faults on the tabular grains as well as the visualization of the morphology and defect structure of silver filaments formed during development of microcrystals. Zero-loss filtering was also used to obtain high-resolution point diffraction patterns of the crystals with low background, containing extra reflections at commensurate positions in between the Bragg reflections probably due to a number of defects in the shell region.

7920K - Other electron surface impact phenomena.
8270K - Emulsions and suspensions.
6180M - Channelling, blocking and energy loss of particles.
8280P - Electron spectroscopy for chemical analysis photoelectron, Auger spectroscopy, etc..
8280D - Electromagnetic radiation spectrometry chemical analysis.
7320M - Collective excitations surface states.
7145G - Exchange, correlation, dielectric and magnetic functions, plasmons.
6170P - Stacking faults, stacking fault tetrahedra and other planar or extended defects.
7155H - Impurity and defect levels in other nonmetals.
6170J - Etch pits, decoration, transmission electron microscopy and other direct observations of dislocations.

Key words
defect states -- dislocation structure -- electron energy loss spectra -- electron spectroscopy -- microemulsions -- plasmons -- silver compounds -- spectrochemical analysis -- stacking faults -- surface plasmons -- X ray chemical analysis -- X ray microscopy -- double structure tabular microcrystals -- emulsions -- electron energy loss spectroscopy -- zero loss electron spectroscopic imaging -- energy dispersive X ray microanalysis -- EELS -- AgBr sub 1 x I sub x tabular microcrystals -- low intensity bands -- bulk plasmons -- surface plasmons -- defect plasmons -- interband transitions -- EDX spot analysis -- dislocation grid faults -- stacking faults -- tabular grains -- morphology -- zero loss filtering -- high resolution point diffraction patterns -- commensurate positions -- Bragg reflections -- shell region -- AgBrI

© EDP Sciences 1995