Angle Effects

We have developed another bench for the measurement of the contrast value. Contrast measurement have been carried out on the MMA fabricated by Texas Instrument, in order to establish the test procedure (Zamkotsian et al., 2002a Zamkotsian et al., 2003). We can address several parameters in our experiment, as the size of the source, its location with respect to the micro-elements, the wavelength, and the input and output pupil size. In order to measure the contrast, the micro-mirrors are tilted between the ON position (towards the spectrograph) or the OFF position (towards a light trap). Contrast exceeding 400 has been measured for a 10° ON/OFF angle. Effects of object position on the micro-mirrors and contrast reduction when the exit pupil size is increasing have also been revealed. 

In 2001, hybrid QM/MM strategies such as those in Section 3, provided a step forward in the modeling of real-world catalysts. However, the scope of these methods is also limited, because they only enable us to properly treat steric effects. Despite this drawback, some important aspects can be studied using these methods. Regioselectivity in diphosphine systems is explained by non-bonding interactions and bite angle effects. However, the role of ea complexes has not yet been determined. 

They constitute the first rhodium phosphine modified catalysts for such a selective linear hydroformylation of internal alkenes. The extraordinary high activity of 32 even places it among the most active diphosphines known. Since large steric differences in the catalyst complexes of these two ligands are not anticipated, the higher activity of 32 compared to 31 might be ascribed to very subtle bite angle effects or electronic characteristics of the phosphorus heterocycles. 

Effects based on physicochemical behaviours Effects based on the structure Shape of the droplet/contact angle Effect of impurities... 

Bite angle effects in diphosphine metal catalysts Steric or electronic ... 

A. L. (2000) Origin of the bite angle effect on rhodium diphosphine catalyzed hydroformylation. Organometallics, 19, 872-883. 

In their study of the NMR T2 and T2 of crosslinked cis-polyisoprene sheets under extension, von Meerwall and Ferguson 65) found that T2 of the rubber had much smaller anisotropy ( magic angle effect) than that of trace penetrants at the same extension ratio X < 3. However, the penetrant diffusion (referred to the strained dimensions) was within experimental error isotropic these findings are equally valid for C6F6 and n-hexadecane as penetrant. The authors concluded that segment orien-... 

However, recently Pauldrach, Puls and Kudritzki (1986, "PPK") were able to prove that this failure of the theory was caused by one of the crucial approximations made by CAK, namely the "radial streaming approximation". In this approximation the interaction of photospheric photons with the wind plasma is treated as if they were streaming out radially from the stellar surface. This approximation is very poor. Even some stellar radii away from the star the photosphere forms a finite cone angle (Fig. 3), which is crucial for correct treatment of momentum exchange. This "finite cone angle effect" was taken into account by PPK by introducing a correction factor CF to the CAK radiative force fCA. ... 

Bond angle effects. When the carbonyl-carbon is part of a ring system containing 3, 4 or 5 carbon atoms, the decrease in the bond angle of the two sp2-hybridised orbitals results in steric strain effects which cause the frequency of absorption of the carbonyl group to be shifted to higher values. 

Freixa, Z. and van Leeuwen, P.W.N.M. (2003) Bite angle effects in diphosphine metal catalysts Steric or electronic Dalton Trans., 1890. 

---