We have indicated that the lighter atoms such as oxygen in Cu2O can be observed at the specimen with optimal thicknesses based on the dynamic effect of electron diffraction(1). This rule in principle should hold good for the imaging of other lighter atoms such as sulphur atom in Cu2S. However, this point of view needs further experimentally confirm because up to now only oxygen atoms have been observed in Cu2O and a series of new suboxides of copper and nickel (2). In addition, the sulphur atom is much heavier than oxygen one though is still lighter than copper atom. In the present report we provide such a confirmation.The crystallites of Cu2S shown in Fig.l were obtained by sulfurizing at 300°C of the copper thin film which was sealed in a glass tube with mg sulphur left on the tube wall in a vacuum of about 10-2 Pa. The energy dispersive spectrocscopy analysis indicated that they are the sulfides and the electron diffraction analysis indicated they have anti-fluorite structure.
The dynamic effect of incentives on postreward task engagement.
