Fluorescence geometrical effects, measurement

The results of different workers in early measurements of the radiative lifetime of N02 showed considerable disparity ranging from 40 to 90 pis [82, 85—89]. From considerations of the geometries used in the different studies, Sackett and Yardley [83] were able to estimate the probable error in these measurements caused by using too small a fluorescence cell. The results of their calculations showed that the range of lifetimes measured in various studies were consistent with a true lifetime of 65 pis or longer when geometrical effects were taken into account. 

Fluorescence-based measurements are already very sensitive and widely used in bio-medical analysis. However, the metallic nanostructures provide further improvement on the sensitivity and limit of detections through the enhancement of the local field. Therefore, a large number of researchers are dedicated to developing substrates for SEFS [46-52]. The effect of the geometrical parameter of the nanostructure on the efficiency of the SEFS is well illustrated in Fig. 9. In this case, the SEFS enhancement factor (SEFS enhancement factor) is plotted against the periodicity of the arrays of nanoholes in gold films. The experiments were realized by spin-coating the arrays of nanoholes with a polystyrene film doped with the oxazine 720 [48]. 

Ti(acac)2 was rapidly and quantitatively analyzed by X-ray fluorescence (XRF) spectroscopy. Fe(acac)2 was similarly determined by XRF with correction for Compton scattering. An instrumental geometrical factor and an equivalent wavelength were obtained experimentally, while all the other factors were calculated with the mass absorption coefficients of Fe ". K and XRF spectra of Cr(acac)3 and other Cr compounds were measured with a Bragg spectrometer. The relative intensities of the 3, K 2, K / and K lines with respect to the K line confirm the chemical effect on the intensity... 

In addition to geometric requirements, AS/NZ 4399 describes the effect of fluorescent samples on diffuse transmittance measurements for two types of spectrophotometer designs. The discussion is specific to whether the instrument monochromator is placed before or after the sample in other words, whether the sample illumination is monochromatic or polychromatic. 

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