Photon scattering

Taking the photon scattering vector q in z-direction, the dynamical structure factor is related to the Compton profile J(pz) by... 

Thus for an ideal two-phase system the total calibrated intensity that is scattered into the reciprocal space is the product of the square of the contrast between the phases and the product of the volume fractions of the phases, Vi (1 — Vi) = V1V2. V1V2 is the composition parameter66 of a two-phase system which is accessible in SAXS experiments. The total intensity of the photons scattered into space is thus independent from the arrangement and the shapes of the particles in the material (i.e., the topology). Moreover, Eq. (8.54) shows that in the raw data the intensity is as well proportional to the irradiated volume. From this fact a technical procedure to adjust the intensity that falls on the detector is readily established. If, for example, we do not receive a number of counts that is sufficient for good counting statistics, we may open the slits or increase the thickness of a thin sample. 

Inelastic photon scattering processes are also possible. In 1928, the Indian scientist C. V. Raman (who won the Nobel Prize in 1930) demonstrated a type of inelastic scattering that had already been predicted by A. Smekal in 1923. This type of scattering gave rise to a new type of spectroscopy, Raman spectroscopy, in which the light is inelastically scattered by a substance. This effect is in some ways similar to the Compton effect, which occurs as a result of the inelastic scattering of electromagnetic radiation by free electrons. 

The concept of supermolecules allows a rather rigorous treatment of the aspects of collision-induced light scattering in the binary regime. The frequency dependence of the scattered light is described by the differential photon scattering cross section per unit angular frequency and per pair,... 

S. Kielich. Multi-photon scattering molecular spectroscopy. Prog. Optics, 20 155, 1983. 

Fig. 4.15 Raman spectrum of a diatomic gas. The central line corresponds to photons scattered with no frequency change (Rayleigh scattering).

A. Mihelic, M. 2itnik, Ab Initio calculation of photoionization and inelastic photon scattering spectra of He below the N = 2 threshold in a dc electric field, Phys. Rev. Lett. 98 (2007) 243002. 

We will assume that our camera could take the pictures without influencing the motion of the atoms. A real camera would observe light photons scattered off the atoms and these photons would influence the motion of the atoms. 

Nanocrystals and nanowires are utilized in a new generation of solar collectors (a nanometer is one billionth of a meter). In conventional solar cells, at the P-N junction one photon splits one electron from its "hole companion" as it travels to the electron-capturing electrode. If solar collectors are made of semiconducting nanocrystals that disperse the light, according to TU Delft s professor Laurens Siebbeles, an avalanche effect results and one photon can release two or three electrons, because this effect maximizes photon absorption while minimizing electron-hole recombination. This effect of the photon-scattering nanoparticles substantially increases cell efficiency. 

A further parameter of interest is the crystallinity, y, representing the ratio of the number of photons scattered into the diffraction profile peaks to the total number of scatter photons ... 

J H Hubbell, W J Veigele, E A Briggs, R T Brown, D T Cromer and R J Howerton (1975) Atomic form factors, incoherent scattering functions and photon scattering cross-sections. J. Phys. Chem. Ref. Data 4, 471 Errata in 1977, 6, 615. 

A Tartari, C Bonifazzi, J Felsteiner and E Casnati (1996) Detailed multiple-scattering profile evaluations in collimated photon scattering techniques. Nucl. Instrum. Methods B117, 325-332. 

G Harding (1997) Inelastic photon scattering effects and applications in biomedical science and industry. Radiat. Phys. Chem. 50, 91-111. 

M.S. Chapman, T.D. Hammond, A. Lenef, J. Schmiedmayer, R.A. Rubenstein, E. Smith, et al., Photon scattering from atoms in an atom interferometer Coherence lost and regained, Phys. Rev. Lett. 75 (1995) 3783-3787. 

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