Single-Molecule Spectroscopy

As modern research seeks understanding of processes on a fundamental and molecular level, single-molecule spectroscopy has become an important tool to access molecular distributions instead of mean values, resolve molecular heterogeneities, and detect rare or hidden events. Most single-molecule applications use fluorescence microscopy to monitor different states of the fluorescently labeled molecules. The readout can be as simple as the detection of fluorescence intensity (eg, in single-molecule tracking or fluorescence correlation spectroscopy) or its spectroscopic characteristics (eg, spectrum, excited-state lifetime, or polarization) reporting on related structural or dynamic changes. The fundamental principles and basic techniques required for single-molecule experiments are explained in this article.