Kerr gated fluorescence microscopy

Kerr-Gated Femtosecond Fluorescence Microscopy and Micro-Spectroscopy (KGFM)... 

Since a molecule or a quantum dot can emit no more than one photon per excitation, the optimum source for ultrafast fluorescence microscopy has a high repetition rate (10 -10 Hz) and a pulse energy sufficient to pump an excitation NOPA (noncollinear optical parametric amplifier) and to drive the Kerr or up-conversion gate. The current configuration of the Rutgers microscope relies on a cryogenically cooled Ti sapphire regenerative amplifier which produces 50 gJ... 

Certain chromophore systems are intrinsically predisposed for ultrafast single molecule microscopy. Among these, emitters coupled to metal surfaces stand out as exceptionally well-suited subjects. Numerous observations of substantial radiative rate enhancement at the surface or in the vicinity of the surface of a metal were reported. Radiative rate enhancements as large as 10 have been predicted for molecular fluorophores and for semiconductor quantum dots coupled to optimized nanoantennae.Such accelerated emission rates put these systems well within the reach of the emerging femtosecond microscopy techniques. As a result, we decided to apply the Kerr-gated microscope to study of fluorescence dynamics of individual core-shell quantum dots in contact with smooth and nanostructured metal surfaces. 

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