Purple Membrane by X-ray Photoelectron Spectroscopy

Purple membrane is a constituent of the cell membrane of Halobacterium halobium. It is of technological interest due to the very fast, efficient electrical response to light of its integral protein, bacteriorhodopsin. Dried films of purple membrane are of importance for the fabrication of devices from this material. In this article, x-ray photoelectron spectroscopy (XPS) spectra of purple membrane fragments dried on SiO₂ are presented. To remove excess lipid from the substrate surface, the samples were washed with distilled water subsequent to the purple membrane drying step. The presence of purple membrane fragments on the substrate surface was verified by atomic force microscopy prior to XPS analysis.