In early experiments of one technique, elastic stretching of these things resulted in a pressure gradient, necessitating the creation of pressure-transmitting media. In variations of one technique, higher resolution imaging may be achieved by fitting one of these things with a microSQUID. The movement of electrons between a sample and one of these things is modeled by a rectangular potential of height on the order of the work function of the surface of these things. One of these things is fixed to the free end of a (*) cantilever in an atomic force microscope. In one technique, a piezoelectric tube attached to an extremely sharp, conducting example of these things (10[1])applies a bias voltage, allowing for electrons to tunnel through the vacuum separating the sample and this thing. For 10 points, in scanning tunneling microscopy, what part of the apparatus is suspended directly above a (10[1])sample? ■END■