Knowledge Bank

Raman displacements $\Delta \sigma$ (in cycles/cm), semiquantiative relative intensities I, and quantitative depolarization rations $\rho$ for the liquid; and infrared wave numbers $\sigma$ and estimated intensities $Ie$ for both the gas and the liquid; have been obtained for $Cl2C=CHF$ (1,1-dichlorofluoroethylene). The observed $\Delta \sigma (I)\rho$ values for the fundamentals are: $a\prime \prime ---206(33)P,278(100)0.69\ast$, $461(100)0.09,660(87)0.09,962(vw),1138(12)0.35,1291(16)0.37,1654(43)0.11$, $3107(8)0.25:a\prime \prime -284(100)\ast ,444(22)0.85,801(16)0.79$ (P = polarized, $\mathrm{<mrow\; data-mjx-texclass="ORD">\ast </mrow>}=$ polarization state uncertain because of the small separation of the two lines, v = very, w = weak). The observed $\sigma (I\nu )$ values for the fundamentals are: liquid---655(vvs), 958(vvs), 1137(vvs), 1288(vvs), 1648(vvs), 3107(vs), 799(vvs); gas---663(vs), 966(vvs), 1147(vvs), 1291(s), 1654(vvs), 3107(s), 797(vs) (v = very, s = strong). The probable values of $\sigma 1(\sigma g)(\sigma g---\sigma l)$ are: $a\prime ---3107(3107)0,1651(1654)3,1290(1291)1,1138(1147)9,960(966)6,658(663)5,461(464\ast ),278(281\ast ),206(209\ast );a\prime \prime ---800(797)(---3),444(447\ast ),281(287\ast )(l=$ liquid; g=gas; $\mathrm{<mrow\; data-mjx-texclass="ORD">\ast </mrow>}$=estimated value = $\sigma l$ plus the average observed value of $\sigma g\sigma 1$, or $\sigma 1+3c/cm$). To cheek the assignments, a normal coordinate analysis was made by the Wilson method, using a potential energy function of the Urey-Bradley type and an IBM 1620 electronic digital computer. The calculated $\sigma l$ values are: $a\prime ---206,278,462,659,956,1139,1291,1654,3107;a\prime \prime ---284,444,801c/cm$. The maximum and average deviations of these from the observed values are 0.4 and 0.1 per cent. respectively. The probable values of $\sigma g$ were used to calculate the heat content, free energy, entropy, and heat capacity for 12 temperatures from 100 to $1000\circ K$.