Measurements of the Kerr effect (electric birefringence) are reported for the four chloromethanes (CH3Cl, CH2Cl2, CHCl3, CCl4) in the vapour phase over a range of temperature (260-370 K). For CCl4, the second hyperpolarisability γK is found to be (1.23 ± 0.04) × 10-60 C4 m4 J-3, in reasonable agreement with other nonlinear optical measurements. For CH2Cl2, a polarisability anisotropy parameter (α33-α) is determined to be (-0.68 ± 0.08) × 10-40 C2 m 2 J-1, demonstrating the inadequacy of the bond additivity approximation. The first hyperpolarisabilities βK of CH 3Cl, CH2Cl2 and CHCl3 are relatively small and therefore poorly determined, indicating that hyperpolarisability contributions to the Kerr effect of dipolar molecules may in general be less significant than has previously been suggested.
|Number of pages||6|
|Journal||Journal of the Chemical Society, Faraday Transactions 2: Molecular and Chemical Physics|
|Publication status||Published - 1978|