Effect of Accelerating Voltage and Specimen Temperature on Radiation Damage of Hexadecachloro Copper Phthalocyanine

Abstract

In order for the single atoms in organic molecules to be resolved, considerably high magnification would be needed up to 100 to 200 thousand times. A highly bright illumination of electron beam is an essential requirement for this purpose, consequently giving rise to the serious problem of radiation damage. In the course of electron microscopy of organic crystals in respect to their epitaxial growth, it was found that Cuhexadecachloro-phthalocyanine (Cu-Cl16PC), which is wholly chlorinated Cu-phthalocyanine (Cu-PC), is remarkably resistant to radiation damage. This report is to show semiquantitatively the resistivity of the materials against the beam at various accelerating voltages and different specimen temperatures.The specimen were thin crystalline films of Cu-PC and Cu-Cl16PC (Fig.1), all being prepared through epitaxial growth in an ultra high vacuum evaporator. The film thickness was carefully controlled to 200-300A by the use of a quartz crystal oscillator microbalance. The films were supported on carbon microgrid with small holes 1 or 2 microns in diameter as shown in Fig.2.