Methods for the determination of （的确定的方法）.pdf

‘Leader in heavy-metal free quantum dots’ Methods for the determination of photoluminescence quantum yield An overview of the methods used by Nanoco Technologies for the determination of luminescence quantum yields of quantum dots January 2013 © 2013 Nanoco Technologies Limited, All Rights Reserved January 2013 Methods for the determination of photoluminescence quantum yield An overview of the methods used by Nanoco Technologies for the determination of luminescence quantum yields of quantum dots ‘Leader in heavy-metal free quantum dots’ Introduction This report outlines the methods used by Nanoco Technologies for the determination of luminescence quantum yields. Two methods are described: the Relative Method, which relies on the use of fluorescence standards with known fluorescence quantum yields and is really only applicable to solution phase measurements, and the Absolute Method, which is applicable to both solution and solid phase measurements. The determination of fluorescence quantum yields The quantum yield of photo-excited fluorescence is defined as: QY = no. of photons emitted / no. of photons absorbed ….. (1) [Strictly speaking, since fluorescence measurements are normally performed under conditions of steady-state illumination, the number of photons emitted or absorbed in this equation is actually photons per unit time - i.e. the rate of emission/absorption]. Using a fluorimeter in “standard” mode, with right-angle illumination of a solution sample, it would not be a trivial matter to determine precisely the number of photons being emitted and absorbed by the sample. Only a very small (and unknown) fraction of the light emitted from the sample actua