Fluorescence scattering

Spectroscopic detectors, which measure different spectral properties (absorption, fluorescence, scattering, etc.), may be element selective, structure or functionality selective, or property selective. The most common... 

LEAFS Laser-excited atomic fluorescence scattering... 

Another type of intrinsic property is derived from the theory of light scattering in particles. The phenomenon of Raman and fluorescent scattering from molecules suspended in small dielectric particles exemplifies such prop-... 

Chowdhury, M. H., Gray, S. K., Pond, J., Geddes, C. D., Aslan, K., and Lakowicz, J. R. (2007). Computational study of fluorescence scattering by silver nanoparticles Journal of the Optical Society of America B-Optical Physics 24 2259-2267. 

Batterman, B. W. (1969). Detection of foreign atom sites by their x-ray fluorescence scattering. Phys. Rev. Letters, 22, 703-5. 

Figure 7. Plots of observed fluorescence (scatter plot) and calculated fluorescence (smooth line) from 10 (iM dansyl-L-proline and 5 pM bovine serum albumin (top). The fitted parameters are X[ = 2.61ns, Xj = 22.6ns, a, = 0.864 and a, = 0.136. Also shown is a plot of the residuals (bottom).

Dashed lines correspond to the two components of the Lorentzian envelope fitted to the spectrum (smoothed solid line). Linear solid lines represent fluorescence scattering and are taken as ground levels (taken from Ref. 252). 

The experimental station contains manipulators to positions the sample, optics to view the sample, and detectors to measure the fluorescent, scattered or diffracted X-rays. The details of these apparatus depend entirely on the type of experiment to be performed. For example, an XRF microprobe requires a precision X-Y-Z sample stage, high quality microscope and multi-element fluorescence detector. A surface scattering experiment, on the other hand requires a 4-circle goniometer and a low-noise photon counting detector. 

Batterman BW (1964) Effect of dynamical diffraction in X-ray fluorescence scattering. Phys Rev 133 A759-764... 

Element concentrations from XRF spectra. The pXRF spectrum consists of various peaks due to fluorescence, scattering, and detector artifacts such as escape and pileup peaks. The basic procedure for obtaining quantitative compositional information from XRF spectra is to fit a background spectrum, subtract the background, fit the remaining peaks to obtain net peak areas, and use these net areas to compute concentrations, where the concentration calculations include information on the analysis conditions and physical state and major element composition of the sample. 

Nondescanned (or direct ) detection solves a problem endemic to fluorescence scattering in deep sample layers. Fluorescence photons have a shorter wavelength than the excitation photons and experience stronger scattering. Photons from deep sample layers therefore emerge from a relatively large area of the sample surface. To make matters worse, the surface is out of the focus of the objective tens. Therefore the fluorescence cannot be focused into a pinhole. 

Fig. 5.138 Double-exponential lifetime fit to the data of Fig. 5.137 in a time window indicated by the cursor lines. Fluorescence, scattering, and convolution of scattering curve with calculated decay function. Lower part Residuals of the fit...

Although there are numerous techniques that utilize the bright and intense beams generated by synchrotron radiation (see Brown and Sturchio 2002) we will focus in this chapter on three of the more common X-ray techniques most applicable to indoor dust (absorption, fluorescence, scattering). In particular, this chapter will provide more emphasis to describing the X-ray absorption fine stmcture (XAFS) spectroscopy over the more well-known XRD and X-ray fluorescence techniques. 

However, quantitative analysis is more complicated. We [4.10,11] have recently given theoretical arguments to show that the angular distribution, intensity, and polarization of the Raman or fluorescent scattering signal will not only depend upon the number of active molecules but also upon the particle size, shape, refractive index, internal structure, and the distribution of the active molecules within the particle. This will be illustrated in this chapter by representative calculations. 

Fig.4.14. Fluorescent scattered inten-sities Ij vs scattering angle for a sphere coated with active molecules just beneath the outer surface a = 5 (solid...

The attenuation of light by a particle includes contributions from elastic scattering and absorption. The absorbed photons induce transitions leading to Raman or fluorescence scattering or contribute to the internal heating of the particle. The extinction cross section is the sum of the elastic-scattering cross section and the absorption cross section. The corresponding efficiency factors formed by... 

Figure 29.1 A section through the cylinder of a glass engine showing the windows for the input and outlet of a laser beam (sheet), atthe top of the cylinder, and the window for collection of fluorescence/scattered light, in thetop of the piston. Reproduced from Knapp et al, AppL Opt, 1996, 35 4009, with permission of the Optical Sodely of America...

Nuclear resonance fluorescence scattering provides evidence for Coulomb fragmentation of P Xe molecules following decay in II. The chemical behaviour of carrier-free radio-iodine, produced by beta decay, has been studied. ... 

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