A quasielastic neutron scattering study of the dynamics of alkane and ether molecules tethered to the surface of MCM-41

Abstract

The motion of 1,3-diphenylpropane (DPP, ��Si-O-C6H4(CH2)3C6H5) and phenethyl phenyl ether (PPE, ��Si-O-C6H4(CH2)2OC6H5 and ��Si-O-C6H4O(CH2)2C6H5) tethered to the interior pore surface of MCM-41 silica was investigated using quasielastic neutron scattering. Quasielastic scans over an energy range of �} 17 ��eV were carried out at temperatures in the range 240-320 K using the High Flux Backscattering Spectrometer at the NIST Center for High Resolution Neutron Scattering. Quasielastic data were fit with a single-lorentzian and a delta function, convoluted with the instrument resolution. These results elicit the role temperature has on the motion of these molecules tethered within the pores and the interactions of the molecules with the pore walls.