Reversible bending motion

During the course of experiments to reveal an electric field effect on the behavior on the photogenerated mobile ions, we found a peculiar phenomenon, reversible bending motion of the rod-shaped gels. The result will also be briefly described. 

Recent ab initio calculations have attempted to probe the fundamental source of the reversal of H/D preference in ionic as compared to neutral systems, using water as a test base. A harmonic analysis of the potential energy surface of the water dimer, computed with a 6-31G basis set, indicates that the preference for D in the bridging site can be explained in a manner similar to that described earlier for HF - HF. The frequency of the bending motion of the bridging atom is sensitive to its mass this effect leads to a lower vibrational energy of some 0.2 kcal/mol when the heavier D undergoes this motion. The computations indicated that electron correlation has little effect upon this conclusion, even its quantitative aspects. While the treatment was purely harmonic in nature, other calculations have indicated that anharmonicity effects yield very little distinction between one isotopomer and the next. 

The amplitude drops to zero when the sample is moved from the point of first contact on a distance of the half of the full amplitude of the free-oscillating probe. From this point, a further motion of the sample will cause the cantilever bending upward, similar to what occurred in the contact mode. If the sample motion is reversed the amplitude increases as shown by a dashed curve in Figure 20.2c. 

Figure 12 FeCO bending modes predicted by DFT. The relative phase of the FeCO bending and porphyrin motions reverses between 560 and 580 cm ...

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