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New developments in optical studies of single molecules at room temperature have been assembled with concentration on underlying principles and the potential of single-molecule experiments. Single-molecule-studies examples include those that involve photochemistry and photophysics experiments related to spectral fluctuations, single-molecule measurements, Raman spectroscopy, conformational dynamics, diffusional motions, fluorescence resonant energy transfer, enzymatic turnovers and exciton dynamics. These studies are an illustration of the information that can be obtained with the single-molecule approach not easily seen in ensemble-averaged measurements.

The near-field optical interaction between a sharp probe and a sample of interest can be exploited to image, spectroscopically probe, or modify surfaces at a resolution (down to - 12 nm) inaccessible by traditional far-field techniques. Many of the attractive features of conventional optics are retained, including noninvasiveness, reliability, and low cost. In addition, most optical contrast mechanisms can be extended to the near-field regime, resulting in a technique of considerable versatility. This versatility is demonstrated by several examples, such as the imaging of nanometric-scale features in mammalian tissue sections and the creation of ultrasmall, magneto-optic domains having implications for high-density data storage. Although the technique may find uses in many diverse fields, two of the most exciting possibilities are localized optical spectroscopy of semiconductors and the fluorescence imaging of living cells., Optical microscopy is such a pervasive technology that it is easy to take its impact for granted. On the scientific end, its applicability ranges from the imaging of living specimens, [...]