By using the second harmonic generation (SHG) microscope, two-dimensional d
istribution of SHG-active domains of merocyanine J-aggregates at the air-wa
ter interface was successfully observed. It was found that the ionic compou
nd of the subphase strongly influenced the form, size and anisotropy of the
SHG-active domains. (C) 1999 Elsevier Science S.A. All rights reserved.