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χ(3) scattering noises in nonlinear optical phase conjugation (1995)

Wu, W. S. ; He, Q. B. ; Yeh, P. ; [weitere]

Springer

Applied physics 61 (1995), S. 611-618

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ISSN: 1432-0649

Schlagwort(e): 42.65. - k

Quelle: Springer Online Journal Archives 1860-2000

Thema: Physik

Notizen: Abstract Phase conjugation by Four-Wave Mixing (FWM) is treated quantum mechanically as a multiphoton scattering process. The spontaneous scattering of two counter-propagating photons gives rise to a background noise, whereas the stimulated scattering in the presence of the probe beam generates the phase conjugate signal. In addition, the stimulated scattering also contributes to a background noise which has never been discussed. Compared with Rayleigh scattering noise, the χ(3) scattering noises are relatively small for intensity up to 108 W/cm2. For higher intensities, the χ(3) scattering noises, in conjunction with the Rayleigh scattering noise, will affect the spatial fidelity of the optical phase conjugation.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF01091221

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Digitale Medien

the effect of phosphate on the transformation of ferrihydrite into crystalline products in alkaline media (1997)

Paige, C. R. ; Snodgrass, W. J. ; Nicholson, Ronald V. ; [weitere]

Springer

Water, air & soil pollution 97 (1997), S. 397-412

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ISSN: 1573-2932

Schlagwort(e): desorption ; ferrihydrite ; modelling ; phosphate ; TEM ; transformation ; wastewater

Quelle: Springer Online Journal Archives 1860-2000

Thema: Energietechnik

Notizen: Abstract The presence of phosphate retards the transformation of ferrihydrite into crystalline products. Increasing phosphate from 0 to 1 mole % results in an order of magnitude decrease in the rate of transformation of ferrihydrite at pH 12. Levels of phosphate of ∼1 mol % suppress the formation of goethite (α-FeO(OH)) and result in the formation of a product consisting of η-Fe2O3. Higher levels of phosphate result in the ferrihydrite remaining amorphous, even after several hundred hours. Phosphate prevents formation of goethite by hindering the dissolution of ferrihydrite rather than by interfering with nucleation and growth of goethite in solution. The transformation rate of pure ferrihydrite is also strongly inhibited in the presence of dissolved phosphate. This is due to surface complexation. The transformation rate was measured at temperatures of 60 °C and 70 °C. The rate of transformation was found to be described by either (i) a solid-state reaction equation for powdered compacts or (ii) a zero-order reaction controlled by desorption. The transformation of the ferrihydrite matrix was accompanied by the loss of the phosphate trace component. X-ray diffraction indicates that no solid solution involving phosphate substitution into η-Fe2O3 is formed. Transmission electron microphotographs of the original precipitates containing phosphate confirm the presence of the phosphate and demonstrate its involvement in linking together extremely small particles of ferrihydrite.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1023/A:1026416426611

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Digitale Medien

The effect of phosphate on the transformation of ferrihydrite into crystalline products in alkaline media (1997)

Paige, C. R. ; Snodgrass, W. J. ; Nicholson, Ronald V. ; [weitere]

Springer

Water, air & soil pollution 97 (1997), S. 397-412

zur Merkliste hinzufügen auf der Merkliste

Details

ISSN: 1573-2932

Schlagwort(e): desorption ; ferrihydrite ; modelling ; phosphate ; TEM ; transformation ; wastewater

Quelle: Springer Online Journal Archives 1860-2000

Thema: Energietechnik

Notizen: Abstract The presence of phosphate retards the transformation of ferrihydrite into crystalline products. Increasing phosphate from 0 to 1 mole % results in an order of magnitude decrease in the rate of transformation of ferrihydrite at pH 12. Levels of phosphate of ∼1 mol % suppress the formation of goethite (α-FeO(OH)) and result in the formation of a product consisting ofη-Fe2O3. Higher levels of phosphate result in the ferrihydrite remaining amorphous, even after several hundred hours. Phosphate prevents formation of goethite by hindering the dissolution of ferrihydrite rather than by interfering with nucleation and growth of goethite in solution. The transformation rate of pure ferrihydrite is also strongly inhibited in the presence of dissolved phosphate. This is due to surface complexation. The transformation rate was measured at temperatures of 60 °C and 70 °C. The rate of transformation was found to be described by either (i) a solid-state reaction equation for powdered compacts or (ii) a zero-order reaction controlled by desorption. The transformation of the ferrihydrite matrix was accompanied by the loss of the phosphate trace component. X-ray diffraction indicates that no solid solution involving phosphate substitution intoη-Fe2O3 is formed. Transmission electron microphotographs of the original precipitates containing phosphate confirm the presence of the phosphate and demonstrate its involvement in linking together extremely small particles of ferrihydrite.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF02407475

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