Protein monolayers: Surface enhanced infrared difference absorption spectroscopy (SEIDAS)
In order to obtain a monolayer sensitivity, it is necessary to enhance the signals from such a small amount of molecules on surfaces. One of the solutions for this problem is to use unique characteristics of metal surfaces. It has been known that some metals such as gold, silver or copper enhance the signal of adsorbed molecules ca. 105~6 and 102~3 times, for Raman and IR respectively. These phenomena are known as Surface Enhanced Raman Scattering (SERS) and Surface Enhanced Infrared Absorption (SEIRA). We employ these phenomena in combination with the ATR configuration to provide us with detailed information on membrane protein monolayers.