Deep-UV Laser-Based Fluorescence Lifetime Imaging Microscopy of Single Molecules

Deep ultraviolet (deep-UV) laser-based fluorescence lifetime imaging microscopy of single dye molecules adsorbed on quartz glass surfaces is presented. The instrumental setup uses a mode-locked diode-pumped picosecond laser emitting at 266 nm with a repetition rate of 40 MHz. Applying the time-resolved single-photon counting method, we investigated the laser dye 2,2‘ ‘‘-dimethyl- p -quaterphenyl and obtained the fluorescence intensity and fluorescence lifetime images of individual adsorbed molecules. The described setup is also well-suited for biological applications for ultrasensitive detection of intrinsic fluorescence after UV excitation.