State-Selected and State-to-State Ion-Molecule Reaction by Michael Baer, Cheuk-Yiu Ng

By Michael Baer, Cheuk-Yiu Ng

The purpose of this sequence is to assist the reader receive normal information regarding a wide selection of subject matters within the huge box of chemical physics. specialists current analyses of topics of curiosity to stimulate new learn and inspire the expression of person issues of view.

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State-Selected and State-to-State Ion-Molecule Reaction Dynamics. P. 2. Theory

The purpose of this sequence is to assist the reader receive common information regarding a large choice of issues within the extensive box of chemical physics. specialists current analyses of topics of curiosity to stimulate new learn and inspire the expression of person issues of view.

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65. The fact that the I–Ch coexistence concentrations agree with the KS theory provides an indirect test of the KS theory. However, a more stringent test of this theory would be to measure the nematic order parameter. It is possible to induce the cholesteric to nematic phase transition by placing the sample in a sufficiently strong magnetic field (Meyer 1968; Meyer 1969). This fact was used to prepare uniformly aligned monodomain nematics and subsequently to measure their nematic order parameter.

The best way to observe the cholesteric texture such as the one shown here is to fill a cylindrical X-ray capillary and focus on its midplane. (After Dogic and Fraden, 2000). 3 Experimental Phase Diagram of an fd Virus Suspension In thermotropic liquid crystals it is conventional wisdom that chiral molecules will form a cholesteric phase while achiral molecules will form a nematic phase. However, this does not seem to be true for colloidal rods, and the molecular origin of the cholesteric phase remains poorly understood.

For example, at 1 mM ionic strength, Deff ≈ 60 nm, which results in the aspect ratio L/Deff ≈ 15. 3 clearly shows that for these small aspect ratios third and higher virial coefficients cannot be ignored. Indeed, the results of the scaled particle theory, which include these higher coefficients, predict that the I–N(Ch) transition is located at significantly lower concentration than that found by the experiments and Chen’s theory. The agreement between the scaled particle theory, experiments, and Chen’s theory is much better at high ionic strength where the effective aspect ratio is large (at 100 mM ionic strength, L/Deff ≈ 83), and therefore the excluded-volume interactions are more accurately approximated by the second virial coefficient.

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