Enhancing single-molecule photostability by optical feedback from quantum jump detection

We report an optical technique that yields an enhancement of single-molecule photostability by greatly suppressing photobleaching pathways which involve photoexcitation from the triplet state. This is accomplished by dynamically switching off the excitation laser when a quantum jump of the molecule to the triplet state is optically detected. The resulting improvement in photostability unambiguously confirms the importance of photoexcitation from the triplet state in photobleaching dynamics and will allow the investigation of new phenomena at the single-molecule level. © 2008 American Institute of Physics. #DOI: 10.1063/1.3013843$