高浓度若丹明6G溶液荧光寿命的测量

MEASUREMENT OF FLUORESCENCE LIFETIME OF RHODAMINE 6G SOLUTIONS WITH HIGH CONCENTRATION

本文提出一种测量高浓度溶液荧光寿命的方法.利用这种方法测量了浓度范围从1×10^(-6)至1×10^(-2)mol·L^(-1)的Rh6G乙醇溶液的荧光寿命.并证明了在这个浓度范围内,Stern-Volmer公式仍然成立.

The fluorescence lifetime of fluorescent materials in solution is often measured in the case of low concentration. But the medium of dye laser is always high concentration solution, generally in ihe range of 10-4~ 10-2mol???????L-1. It is necessary to measure the parameters,such as quantum yield and fluorescence lifetime, of high concentration solution in order to studying the physical and chemical behaviors of the laser dye. However, it is difficult to accurately measure the fluorescence lifetime because of the existance of self-absorption and re-emission of the fluorescence molecules in high concentration solution.Recently, several authors have developed some methods for measuring the fluorescence lifetime of high concentration solutions. But these methods are either complicated in experimental setup or tedious in calculation, and inconvenieat to use. In this paper, we report a simple method for measuring the fluorescence lifetime in high concentration solutions. N2 laser was used as an excitation source and the fluorescene was observed at 90??????????? angle to the incident light. The laser beam was kept to irradiate the sample by the inner surface of the emission window of the cell. The whole emission window was hid by a thin black plate on which there was an aperture of 0.4mm in width by the inner surface of the incident window. The fluorescence emitted from this aperture was exactly measured. Thus,both of the transmission range of the incident laser beam and the travelling distance of the fluorescence emitted by the excited molecules in the cell are much shorter. The self-absorption and re-emssion of the molecules can be ignored and the accurate fluorescence lifetime can be obtained. Using this method we have measured the fluorescence lifetimes of Rh6G in ethanol solution with concentration from 1XXXXXXXX10-6 to 1XXXXXXX10-2mol??????L-1. The results show shat Stern-Volmer formula still holds in this concentration region.