Ak. Ray et al., AN INTERPRETATION OF THE STRUCTURE OF LANGMUIR-BLODGETT-FILMS OF OCTA-SUBSTITUTED METAL-FREE PHTHALOCYANINE MOLECULES FROM OPTICAL-SPECTRA, Philosophical magazine. B. Physics of condensed matter.Statistical mechanics, electronic, optical and magnetic, 78(1), 1998, pp. 53-64
Ultraviolet-visible absorption spectra of Langmuir-Blodgett (LB) films
of octa-substituted metal-free phthalocyanine molecules are decompose
d into Gaussian-Lorentzian components in order to compare the in-plane
molecular arrangements of the two groups of the compounds with short
and long alkyl chains. LB films of long-chain molecules represent the
Davydov splitting of the Q band, which corresponds to the 'herringbone
' molecular structure and the angle between the molecules is estimated
to be 75 degrees. For short-chain molecules, the largely broadened 'b
lue' component of the Davydov doublets is suppressed and this can be e
xplained by the domination of an anisotropic stack-like molecular arra
ngement in LB films.