Infrared intensity analysis of MXY₂ type molecules has been attempted. The dipole momentμ of C=O is obtained to be different for different moleculesviz. for CH₂O, 1.9052; for COCl₂, 1.1517; for COF₂, 0.6340; and for COBr₂, 0.7687. Similarly in the case of CSF₂ and CSCl₂μ_C=S it was found to be 0.2473 and 0.2983 respectively. This shows that the effect of the electro-negative halogen atoms is very important.

In the infrared spectra of molecules with more than one C-H bond the symmetric and antisymmetric stretching bonds often overlap, causing uncertainty in the intensity analysis. For CH₂Cl₂ and CD₂Cl₂ in the vapour state, the two bands overlap to such an extent that Straley who takes it as one band attributes it to antisymmetric stretching while Saekiet al assign it to the symmetric stretching. Following the method of analysis initiated in this laboratory, we have solved this problem by ultimately obtaining intensities separately forA₁ andB₂ species. The band is mostly due to the symmetric stretching, 0.06 out of the total of 0.31 contributing toB₂. Thus, this gives a method of separating the intensities of bands which are highly overlapping.

Raman and infrared intensity analysis of CHCl₃ is attempted to determine the bond polarisability derivatives and bond dipole moments and their derivatives respectively, on lines expained in our earlier papers.