Radiation damage mechanisms in copper phthalocyanine and its chlorinated derivatives

Radiation damage in the TEM and SEM

“…Surrounding molecules are thought to provide a 'cage effect' which hinders the displacement of the larger halogen atoms. Consistent with this idea, damage to chlorinated Pc was found to occur heterogeneously, producing amorphouslike regions within the crystalline matrix (Clark et al, 1980). A more quantitative measure of damage is a characteristic dose D e ; defined as the dose at which the effect being measured decreases to 1/e ¼ 37% of its value at the start of irradiation.…”

Atomic resolution ADF-STEM imaging of organic molecular crystal of halogenated copper phthalocyanine

“…Moreover, the Debye-Waller factor for organic crystals is generally large compared to that of inorganic crystals, which means that the elastic component can be dumped more rapidly and the TDS signals become dominant even at lower scattering angles. There is also the possibility that the highangle diffraction intensity is weakened by electron irradiation damage in organic molecular crystals [25]. Therefore, the present detection angle ensures that incoherent imaging is dominant even in LAADF-STEM for organic crystals such as Cl 16 -CuPc with large lattice dimensions.…”

High‐resolution imaging of organic crystals

“…At lo-% the material is chemically much different from the original compound but most of the carbon atoms are still in their lattice positions. There is a thermodynamic preference for the carbon atoms to move to a graphitic structure but while a large number of peripheral atoms remain, such movement is hindered-the cage effect (Clark et al, 1980;Glaeser, 1971). Thus if the concentration of peripheral atoms in the lattice-e.g., hydrogen-is kept high by encapsulation or low temperature then the rate of formation of carbonaceous residue is reduced (Fryer and Holland, 1984;Siegle, 1972).…”