Department of Physics of Complex Systems, Weizmann Institute of Science, Rehovot, Israel 76100.
ACS Nano. 2012 Oct 23;6(10):8778-82. doi: 10.1021/nn302551v. Epub 2012 Oct 4.
Although colloidal quantum dots (QDs) exhibit excellent photostability under mild excitation, intense illumination makes their emission increasingly intermittent, eventually leading to photobleaching. We study fluorescence of two commonly used types of QDs under pulsed excitation with varying power and repetition rate. The photostability of QDs is found to improve dramatically at low repetition rates, allowing for prolonged optical saturation of QDs without apparent photodamage. This observation suggests that QD blinking is facilitated by absorption of light in a transient state with a microsecond decay time. Enhanced photostability of generic quantum dots under intense illumination opens up new prospects for fluorescence microscopy and spectroscopy.
尽管胶体量子点（QDs）在温和激发下表现出优异的光稳定性，但强烈的光照会使其发射变得越来越间歇性，最终导致光漂白。我们在不同功率和重复率的脉冲激发下研究了两种常用类型的 QD 的荧光。研究发现，在低重复率下，QD 的光稳定性显著提高，允许 QD 进行长时间的光学饱和而不会出现明显的光损伤。这一观察结果表明，QD 的闪烁是由具有微秒衰减时间的瞬态吸收光来促进的。在强光照下，通用量子点的增强光稳定性为荧光显微镜和光谱学开辟了新的前景。
