Single molecule spectroscopy experimental applications

In recent years, a new approach to condensed-phase spectroscopy has emerged, that focuses on the spectral properties of a single molecule (SM) embedded in a condensed phase [14], Thanks to experimental advances made in optics and microscopy [5], it is now possible to perform single molecule spectroscopy (SMS) in many different systems. Motivations for SMS arise from a fundamental point of view (e.g., the investigation of the field-matter interaction at the level of a SM and the verification of statistical assumptions made in ensemble spectroscopy) and from the possibility of applications (e.g., the use of SMS as a probe for large biomolecules for which a SM is attached as a fluorescent marker). 

Spectroscopy remains the routine experimental application of quantum mechanics. A typical spectroscopy experiment uses large numbers of photons to probe the properties of individual atoms and molecules. Each photon interacts with only one molecule at a time, bringing the experiment to the nanometer distances—the quantum scale—of single molecules. By measuring how a beam of photons is affected by its interaction with matter, we can now deduce the quantum properties of the substance. As we develop the theory of atomic and molecular quantum mechanics over the next several chapters, we will keep coming back to the practical issue of how our results can be supported by laboratory spectroscopy. 

J. B. Foresman and H. B. Schlegel, Application of the Cl-Singles Method in Predicting the Energy, Properties and Reactivity of Molecules in Their Excited Slates in Molecular Spectroscopy Recent Experimental and Computational Advances, ed. R. Fausto, NATO-ASI Series C, Kluwer Academic, The Netherlands, 1993. 

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