title: Image contrast of biological materials in high-voltage electron microscopy.
abstract: A new and simple expression has been formulated for the estimation of contrast of amorphous specimens in the tilted-beam mode of dark-field (DF) imaging in a high-voltage electron microscope. DF contrasts have been calculated for AIDS1.DNA, Salmonella typhimurium DNA, human haemoglobin and myoglobin of sperm whale in the range 0.1-3.0 MV and compared with the corresponding bright-field (BF) contrasts. DF contrast is seen to be significantly greater than BF contrast for a wide range of microscope apertures (alpha) and voltages (phi). The ratio of DF to BF contrast was observed to increase with increasing phi and alpha for all the aforesaid specimens.
authors.affiliation: Department of Biochemistry and Biophysics, University of Kalyani, India.
authors.forename: P
authors.initials: P
authors.lastname: Bhakat
authors.forename: D K
authors.initials: DK
authors.lastname: Bhattacharya
mesh_terms: D004247:DNA / Q000648:ultrastructure*; D006801:Humans; D007089:Image Enhancement; D008297:Male; D008854:Microscopy, Electron / Q000379:methods*
chemical_list: D004247:DNA