The chemistry of pyrrolic compounds. XII. Dipyrrylmethanes

1970 ◽  
Vol 23 (12) ◽  
pp. 2443 ◽  
Author(s):  
PS Clezy ◽  
AJ Liepa
Keyword(s):  
Thin Layer ◽  
Bromine Vapour

The synthesis of a range of dipyrrylmethanes, substituted with electrophilic substituents at one or more �-positions, is described. Bromine vapour has been found to be a useful reagent for identifying dipyrrylmethanes on thin-layer plates.

Applications of Photoelectron Microscopy

1976 ◽  
Vol 34 ◽  
pp. 506-507
Author(s):  
William J. Baxter
Keyword(s):  
Electron Microscopy ◽  
Thermal Decomposition ◽  
Chemical Composition ◽  
Ultraviolet Radiation ◽  
Thin Layer ◽  
Edge Effects ◽  
Electron Optics ◽  
Surface Layers ◽  
Crystalline Orientation ◽  
Fluorescent Screen

In this form of electron microscopy, photoelectrons emitted from a metal by ultraviolet radiation are accelerated and imaged onto a fluorescent screen by conventional electron optics. image contrast is determined by spatial variations in the intensity of the photoemission. The dominant source of contrast is due to changes in the photoelectric work function, between surfaces of different crystalline orientation, or different chemical composition. Topographical variations produce a relatively weak contrast due to shadowing and edge effects.Since the photoelectrons originate from the surface layers (e.g. ∼5-10 nm for metals), photoelectron microscopy is surface sensitive. Thus to see the microstructure of a metal the thin layer (∼3 nm) of surface oxide must be removed, either by ion bombardment or by thermal decomposition in the vacuum of the microscope.

Thin-Layer Chromatography

1965 ◽  
Author(s):  
H. R. Bolliger ◽  
M. Brenner ◽  
H. Gänshirt ◽  
Helmut K. Mangold ◽  
H. Seiler ◽  
...  
Keyword(s):  
Thin Layer ◽  
Thin Layer Chromatography ◽  
Layer Chromatography
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