The background for the investigation is described in the Introduction section. As indicated by the Reviewer, the present study is an extension of our previous OH···O binding studies. We have for some time wished to investigate the corresponding NH···O systems. The NH···O type of linkage has the advantage that a wide range of compounds can be investigated; in general, systems of the type NH···O=C with an intervening double bond are not tautomeric, in contrast to the corresponding OH···O=C systems. We have added a remark on this aspect to the Introduction section. - The ‘delay’ of 10 years is due to technical and personal factors of no relevance to the reported results.
Author Response Reviewer 1The manuscript described ''The vibrational NH stretching transitions in secondary amines with intramolecular NH···O hydrogen bonds were investigated by experimental and theoretical methods, considering a large number of compounds and covering a wide range of stretching wavenumbers'' but the paper needs very significant improvement before acceptance for publication.