The in situ characterization of bacteriochlorophyll c in Langmuir monolayers using polarized UV–vis spectroscopy

The in situ arrangement of bacteriochlorophyll c in a Langmuir monolayer was characterized. Hansen's optical theory was applied to the three-layer system, air/pigment monolayer/water and the correlation between surface pressure and the orientation angle of the bacteriochlorophyll transition dipole moments was deduced. On the basis of the s- and p-polarized UV–vis reflection–absorption and transmission spectra, respectively, the refraction index and extinction coefficient of the red (Qy) band of both the monomeric and aggregated forms of the pigment were estimated.