Absolute signs of dipole moment derivatives in carbonyl sulphide

Abstract

By comparison of i.r. intensity measurements and microwave Stark effect information, it is established experimentally that the absolute signs of the dipole moment derivative for carbonyl stretching in OCS is negative; that is ∂p/∂r_CO=–1·5 ee_CO where e is the charge on the proton and e_CO is a unit vector from the carbon towards the oxygen atom, or, in more familiar, non-SI units the dipole moment gradient with respect to CO stretch is 7 D/Å with the oxygen becoming more negative.