We investigated the absolute orientation of bacteriorhodopsin (bR) thin film prepared by the dip-coating technique by means of second harmonic generation (SHG) interferometry. bRs in the bR thin films prepared in this technique tend to have a preference to orient with the cytoplasmic side away from the glass substrate and extracellular side toward the glass substrate. To assist in the analysis, the hyperpolarizability of covalently bound retinal chromophore was also evaluated by a computational calculation.

doi:10.7567/JJAP.52.05DB03