engleski

On the pre-peak in mono-ol X-ray spectra and the related micro-structure from computer simulations

The X-ray spectra of neat 1-alkanols at ambient conditions show a scattering pre-peak [1, 2]. The current consensus is that the pre-peak is related to the chain-like hydrogen bonding of the hydroxyl head group. In this study, we compare the X-ray spectra of neat alkanols, from methanol to 1-octanol, as obtained from experiments and computer simulations. Our results indicate that the scattering pre-peak is not always well reproduced by various force fields, even though all force fields studied herein show a clear chain-formation for all alcohols. The present investigation indicates that the alkyl tail plays an important role, and that the pre-peak is in fact related to the inhomogeneity of the global charge ordering between the charged atoms of the head group and the neutral ones of the alkyl tail part. This conclusion is reached by analysing the various atom-atom contributions to the correlation functions, and in particular the balance between the positive correlations and negative anti-correlations between the charged and uncharged atoms [3]. [1] M. Tomšič, A. Jamnik, G. Fritz-Popovski, O. Glatter and L. Vlček, J. Phys. Chem. B, 111, 1738-1751 (2007) [2] K.S. Vahvaselkä, R. Serimaa, M. Torkkeli, J. Appl. Crystallogr., 28, 189-195 (1995) [3] M. Požar, J. Bolle, C. Sternemann, A. Perera. J. Phys. Chem. B, 124 (38), 8358-8371 (2020)

alcohols ; clusters ; scattering ; experiment ; computer-simulation

nije evidentirano