Light-induced drift

Laser excitation of a SF6-O2-CH4 mixture gives as products CO, CO2, H2O, SO2, SOF2, HF, CF4, and F2O. However, no photoreaction is observed if SF6-CH4 and SF6-O2 are irradiated separately. Sulphur hexafluoride-sensitized dissociation of UF in the presence of H2 and CO as scavengers has also been investigated. A search for a light-induced drift of SF in a mixture with He, MeF, or SF buffer particles has appeared. No positive result was obtained and this is thought to arise as a consequence of various factors, including the complex structure of the SF absorption spectrum. The pressure... 

Light-Induced Drift, E. R. Eliel Continuum Distorted Wave Methods in Ion-Atom Colhsions, Derrick S. F. Crolhers and Louis J. Dube... 

A.D. Streater, J. Mooibroek, J.P. Woerdman, Light-induced drift in rubidium spectral dependence and isotope separation. Opt. Commun. 64, 1 (1987)... 

We have above discussed certain mechanical actions on atoms induced by laser light. Using resonance-radiation pressure atomic beams can also be focused and manipulated in interesting ways [9.233,234]. Several other interesting mechanical effects exist and have been explored. Studied phenomena include light diffusive pulling [9.235], light-induced drift [9.236] and the optical piston [9.237]. 

G. Nienhuis Theory of light-induced drift and the optical piston. Phys. Rev. A 31, 1636 (1985)... 

Let us calculate the correction to the proton polaron direct current density conditioned by light-induced transitions between the sites. This photocurrent calculation is analogous to that of the correction to the drift activation current carried out in the previous subsection [the analogy lies in the fact that operator (276) is similar to the correction to the Hamiltonian if the electric field is taken into account, with the correction being nondiagonal on the operator of the coordinate see expression (236)]. 

Radiation-induced thermocapillary motion of a drop. The temperature gradient is the simplest but not the unique method for bringing about the thermocapillary drift of a drop. If the drop is opaque and the fluid is transparent, one can move the drop by a light beam in a uniformly heated fluid. The radiation absorbed by the drop will heat it nonuniformly, thus producing thermocapillary stresses. For dcr/dT < 0, the drop will drift towards the warmer part, that is, towards the beam. 

The results and discussion which follow show how DRIFT spectroscopy in a controlled environment cell can be used to probe the active sites in synthetic zeolite catalysts, the nature and temperature dependence of the organic species (referred to herein as fragments) bound within the zeolite framework during and after exposure of the zeolite to light hydrocarbons, and, in conjunction with gas chromatography/mass spectrometry (GC/MS), the rate, product specia-tion, and mechanism of the zeolite-induced reforming reactions. 

Fig. 9,4. Spiral wave drift near a virtual line detector, (a) Snapshot of a spiral wave in a thin layer of the light-sensitive BZ reaction. The overlaid dashed line represents the detector. The white curve shows the spiral tip trajectory in the absence of feedback, (b) Trajectory of the spiral wave tip induced by the feedback.

At low frequencies, that is, for frequencies for which the wavelength of light is much larger than the largest dimension of the circuit, the current is the same everywhere in the circuit. In this case, the displacement current inside the material must be matched by an identical current in the external circuit used to maintain the potential difference across the sample. Thus one can observe the drift motion of the electrons inside the sample by monitoring the current induced in the external circuit. In our example, llie current is qv /L, or the product of the injected charge density with its average drift velocity normalized to the sample thickness. 

Figure 5 Effects of light attenuation conditions on culture stability and biomass productivity. For low residence time, low biomass concentration results in light transmission and high rate of photon absorption (ie, high light received per cell) inducing possible culture drift. For high residence time, the dark volume then generated can have a negative effect on biomass productivity due to the promotion of respiration activity, but also results in more stable culture because of a lower rates of photon absorption (ie, lower light received per cell).

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