RESTRICTED DIFFUSION AND MOLECULAR EXCHANGE PROCESSES IN POROUS MEDIA AS STUDIED BY PULSED FIELD GRADIENT NMR

摘要: INTRODUCTION The spatial and time resolution of the PFG NMR technique is directly proportional to amplitude magnetic field gradient. In standard equipment (for example, scanners) typical gradient limited a 1 T/m. Using such pulses it possible make measurements only on structural distances order few microns. Producing higher gradients involves serious technical difficulties. Nevertheless, while in 1980s maximum did not exceed 10 T/m, at present about 100 T/m are used several laboratories. For long we with up 50-100 With special probehead, have achieved real values 500 This considerably broadens scope method its applications. It also opens new window study porous media by range beyond sub-micron level. Some preliminary demonstrate potential this characterize pore space over below μm. Such information essential for relationships between geometry transport properties media.