Microwave absorption in a helical polypeptide molecule

Abstract

Microwave absorption measurements (3, 8.5, 36 and 72 GHz) are reported on three different molecular weight samples of poly(γ-benzyl-L-glutamate), PBLG, in two solvents. In each case a distinct absorption, often quite narrow (the Fuoss-Kirkwood parameter β≃ 1.0), which is almost temperature independent is centred between 2 and 15 GHz. Its frequency, intensity and contour are not inconsistent with a helical-spring mode suggested to account for the abnormal increase in (α_‖–α_⊥) between the visible and 6 MHz. Other possible origins are considered.