Abstract
The molecular anisotropy of polymide layers occurring in Kapton (C22H10N2O5) films was studied using neutron Compton scattering (NCS) by employing the pulsed neutron source (ISIS) at the Rutherford Appleton Laboratory (UK). The widths of atomic momentum distributions along and normal to the Kapton film surface, σp and σc of the H and C atoms were obtained together with the corresponding effective temperatures Tp and Tc and the anisotropy ratio Tp/Tc. The results are interpreted in terms of the in-plane and out-of-plane zero-point motions of the H and C atoms relative to the film surface. The data reveal an anisotropy ratio of Tp/Tc~1.1 which is far lower than that deduced when assuming a rigid planar Kapton molecule, where the ratio is ~1.7. The results are in qualitative agreement with calculations based on the AM1 semi-empirical method included in the GAUSSIAN98 package.