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# TRANSFERABILITY OF ELECTRO-OPTICAL PARAMETERS FOR INFRARED INTENSITIES OF NORMAL PARAFFINS

Please use this identifier to cite or link to this item: http://hdl.handle.net/1811/9946

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 Title: TRANSFERABILITY OF ELECTRO-OPTICAL PARAMETERS FOR INFRARED INTENSITIES OF NORMAL PARAFFINS Creators: Abbate, S.; Gussoni, M.; Zerbi, Giusepp Issue Date: 1976 Abstract: The intensity of infrared absorption for the i-th normal mode $\theta_{1}$ depends on $\left( \frac{\vec{\partial M}}{\partial Q_{i}} \right)^{\circ}$ where $\vec{M}$ is the total dipole moment of the molecule. $\left( \frac{\vec{\partial M}}{\partial Q_{i}} \right)^{\circ}$ can be expressed as $${\left( \frac{\vec{\partial M}}{\partial Q_{i}} \right)}^{\circ} = {\Sigma_{m}} {\left( \frac{\vec{\partial M}}{\partial R_{m}} \right)}^{\circ} \qquad L_{mi}$$, where $R_{m}$ is an internal coordinate, or as $$\left( \frac{\vec{\partial M}}{\partial Q_{i}} \right)^{\circ} = {\Sigma_{m}} \left\{ {\Sigma_{k}} {\left( \frac{\partial _{\mu^{k}}}{\partial R_{m}} \right)}^{\circ} \quad {\vec{e^{ko}}} + {\Sigma_{k}} \mu^{ko} {\left( \frac{\vec{\partial e^{k}}}{\partial R_{m}} \right)}^{\circ}\right\} \quad L_{mi}$$ where $\mu^{ko}$ and $\vec{e}^{ko}$ are the equilibrium bond dipole moments and equilibrium bond directions, respectively. ${\left( \frac{\partial \mu^{k}}{\partial R_{m}} \right)}^{\circ}$ and $\mu^{ko}$ are usually referred to as electrooptical parameters. The ${\left( \frac{\vec{\partial M}}{\partial R_{m}} \right)}^{\circ}$ can be transferred to isotopic derivatives only when $\vec{M^{\circ}}$ = 0; otherwise, they must be corrected for the rotational contributions. On the contrary the electrooptical parameters can be transferred to isotopic derivatives also when $\vec{M^{\circ}} \neq 0;$ moreover, since they refer to groups of atoms in the molecule, they seem more apt to be transferred to chemically similar molecules. Results will be presented of an overlay"" least squares refinement of the electrooptical parameters on the experimental intensity data of $CH_{4}, C_{2}H_{6}, C_{3}H_{8}$ and their isotopic derivatives. The same set of parameters successfully reproduces the infrared spectrum of polyethylene. URI: http://hdl.handle.net/1811/9946 Other Identifiers: 1976-WD-4