Diffusion of Cyclohexane and Cyclopentane Confined in Mesoporous MCM-41

The crystalline MCM-41 sample with pore diameter 3.2 nm was prepared according to a method of Karlsson et al. [2]. The diffusivity (D) was measured on a Bruker Avance DMX 400 spectrometer using the 13-interval pulse sequence due to Sorland et al. [3], which minimizes the effect of internal field gradients. The length of the gradient pulses (δ) and the spacing between the RF pulses (τ ) were always fixed to 0.5 and 1.1 ms, respectively. The value of the z-storage time was 4 and 8 ms for cyclopentane and cyclohexane, respectively. The natural logarithm of the echo attenuation was plotted vs. the square of the field gradient strength g