Single-photon emission and multi-photon emission from single CdTeSe/ZnS quantum dots at room temperature

In this report, single-photon emission and ordered multi-photon emission from single colloidal CdTeSe/ZnS quantum dots at near-infrared wavelength were realized at room temperature. The fluorescence lifetime, blinking, and anti-bunching effect of this single quantum dots at different excitation powers were measured. The relationship between the excitation power and the emission of exciton, biexciton and multiexciton of single quantum dots at a wavelength of 800nm was obtained. The physical mechanism of photoluminescence of the single quantum dots was analyzed.

Real-time molecular-level visualization of mass flow during patterned photopolymerization of liquid-crystalline monomers

Single-particle fluorescence imaging is used to monitor dynamic processes that occur during patterned photopolymerization of liquid-crystalline monomers. A spatial gradient of chemical potential can be created at the border of bright and dark regions by structured illumination in the photopolymerization process, leading to mutual diffusion of polymers and monomers. Analysis of the fluorescence from single quantum dots doped into the monomers at minute concentrations enables visualization of highly directional flow from the illuminated region where the photopolymerization proceeds toward a masked unpolymerized region. This directional mass flow causes flow-induced orientation of the polymers that is subsequently fixed by completion of the polymerization reaction, resulting in a mesoscopic aligned area of the polymer film.