Conjugation in azochromophores DR, DO3, DR1, and their stacking dimers was studied to clarify physical factors underlying strong influence of stacking dimerization on first hyperpolarizability beta of the chromophores revealed earlier. Raman spectroscopy and quantum-chemical computations were employed for this purpose. Characteristic features of Raman spectra of three different types of stacked dimers are revealed. It is shown that conjugation in the studied azochromophores is essentially deteriorated by stacking dimerization, while formation of shifted stacked dimers strengthens conjugation. These findings suggest conjugational origin of influence of the stacking pairing of the chromophores on first hyperpolarizability beta. (C) 2016 Elsevier B.V. All rights reserved.