Abstract
Infrared reflection absorption spectroscopy (IRRAS) can provide information concerning conformation, tilt angle, and head group structure as well as information about protein secondary structure and orientation. The technique in general can be extended by introducing the polarization–modulation (PM) technique to the IRRAS experiment. It takes advantage of the great difference in the absorption of p- and s-polarized light at high angles of incidence. In particular, the sensitivity can be significantly increased. Both IRRAS and PM spectroscopy (PM-IRRAS) have proved to be a versatile and powerful technique for the spectroscopic characterization of biophysical monomolecular films at the air–water interface. Advances in instrumental design coupled with newly developed sampling methodology have enabled researchers to develop these techniques into methods with great sensitivity. This has allowed great insight into not only the study of monolayer structural and conformational analysis but also the study of monolayer spatial and orientational analysis, which has led to increased insights into molecular organization in two dimensions.
