Final answer:
The electron microscope, which includes the scanning tunneling microscope and the transmission electron microscope, allows visualization of specimens at the nanometer scale. Developed in 1931 by Ernst Ruska, these tools have revolutionized the study of microscopic structures by providing magnification and resolution far beyond traditional optical microscopes.
Step-by-step explanation:
An electron microscope is a powerful tool that uses a beam of electrons to visualize specimens at the nanometer scale. The student's description refers particularly to the scanning tunneling microscope (STM), which uses a sharp probe that scans across the surface of a specimen at a very close distance. This allows electrons to tunnel through the gap between the probe and the specimen, with the tunneling current serving as a sensitive indicator of surface features including atoms and their arrangement. Another type, the transmission electron microscope (TEM), accelerates electrons through a thin specimen, capturing detailed images with the help of magnetic lenses.
Both the STM and TEM offer unparalleled magnification and resolution, far exceeding that of traditional optical microscopes. The TEM can resolve details as minute as 0.1 nm and can magnify up to 100 million times, revealing structures like individual atoms and cell nuclei. Meanwhile, the STM allows for the study of surface topography at the atomic scale. Invented by physicist Ernst Ruska in 1931, electron microscopy has revolutionized our ability to observe the minute details of biological, chemical, and physical materials.