NEUTRON COMPTON-SCATTERING FROM SELECTIVELY DEUTERATED ACETANILIDE

With the aim of developing the application of neutron Compton scatteri ng (NCS) to molecular systems of biophysical interest, we are using th e Compton spectrometer EVS at ISIS to characterize the momentum distri bution of protons in peptide groups. In this contribution we present N CS measurements of the recoil peak (Compton profile) due to the amide proton in otherwise fully deuterated acetanilide (ACN), a widely studi ed model system for H-bonding and energy transfer in biomolecules. We obtain values for the average width of the potential well of the amide proton and its mean kinetic energy. Deviations from the Gaussian form of the Compton profile, analyzed on the basis of an expansion due to Sears, provide data relating to the Laplacian of the proton potential. (C) 1998 Elsevier Science B.V. All rights reserved.