Electric Field Effects on IR Absorption of α-Helical Polypeptide

Abstract

Abstract External electric field effects on the IR absorption spectrum of α-helical poly(γ-benzyl-l-glutamate) have been examined with electric field modulation spectroscopy. The electric-field-induced change in each vibrational band is reproduced by a superposition of the absorption spectrum, and its first and second derivative spectra, suggesting that the electric dipole moment and the molecular polarizability change following vibrational excitation. The N–H stretching band at 3291 cm−1 shows the largest change in the magnitude of dipole moment following vibrational excitation.