Abstract

A single molecule in a crystal matrix is a very good example of a two-level system. We describe a new system for single-molecule spectroscopy, Dibenz-anthanthrene in a naphthalene crystal, which we use to illustrate some effects of the coupling of an electronic two-level system to electromagnetic fields. We studied optical saturation and photon bunching due to a metastable triplet level. The triplet population rate and triplet lifetime are so low, that the bottleneck effect of the triplet may be neglected. We also observed variations of the single molecule radiative linewidths, which we attribute to spontaneous emission modifications by surface effects. As expected for this centrosymmetric host and guest molecules, almost all of the studied single molecules showed a quadratic Stark shift with applied dc electric fields.

© 1998 Optical Society of America