Grid-based dynamic electronic publication: A case study using combined experiment and simulation studies of crown ethers at the air/water interface.
Esther R Rousay, Hongchen Fu, Jamie M Robinson, Jeremy G Frey, Jonathan W Essex
School of Chemistry, University of Southampton,
Highfield, Southampton, SO17 1BJ, UK

Abstract The Publication@Source Paradigm and Challenges Body Molecular Dynamics Simulations Comparisons and Conclusions Acknowledgements Appendix:The TriScapeRDF browser References Glossary Search
Case Study Crown ether molecules at the water/air interface Introduction Benzo-15-Crown-5 UV Spectrum of Benzo-15-Crown-5 Surface Tension Measurements Second Harmonic Generation SHG Isotherm SHG Isotherm .2 Polarisation Dependence Polarisation Dependance Analysis The molecular hyperpolarisability and molecular orientation The molecular hyperpolarisability and molecular orientation .2 Analysis

The molecular hyperpolarisability and molecular orientation .2

The benzo-15-crown-5 molecule may be approximated by C2v symmetry (figure 9). This leads to a large reduction in the number of independent non-zero hyperpolarisability components. In addition, as there is no delocalisation in the direction perpendicular to the molecular plane a further simplification occurs leaving only 3 non-zero, independent tensor elements for SHG: βxzx, βzxx and βzzz 21. Comparisons with results from other benzene species indicates that the dominant components of the hyperpolarisablity tensor will be βzxx and βzzz ; approximate calculations with Gaussian 90 confirm these predictions.

Figure 9. Assumed symmetry of the benzo-15-crown-5 . Oz is the molecular axis adn the plane formed by Oz and Ox is the molecular plane.

The relationship between the surface and the molecular properties can be derived assuming the relevant averaging about the azimuthal angle and internal molecular axis of the chromophore. Once the dominant hyperpolarisability components are known, the susceptibility components may be used to derive the orientation parameter, D = 〈cos3Θ〉/〈cosΘ〉 . If the orientational distribution is narrow, then D may be taken as being equal to cos2Θ.

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