Spatial frequency response and transient anisotropy in bacteriorhodopsin thin films

In this paper, we present new results describing the spatial frequency response in bacteriorhodopsin (bR), immobilised in gelatin films. It is shown that the spatial frequency response is flat, as compared to bR contained in solution form. An experimental investigation into the photoinduced anisotropy of bR films is also presented. It is shown that the anisotropy can be induced using two wavelengths (632.8 nm and 454 nm) and is dependent on the pH of the gelatin matrix, the 454 nm laser polarisation and the 454 nm pump power. The mechanisms producing the anisotropy are briefly discussed.