Fast Fourier transforms, molecular-surface

Besides the molecular probe method using gas adsorption,107 162 recently, the TEM image analysis method163"167 has been applied to evaluate the surface fractal dimension of porous materials. The most attractive fact in this method is that the pores in different size ranges can be extracted from the TEM images which include contributions from many different pore sizes by the inverse fast Fourier transform (FFT) operation by selecting the specific frequency range.165 167... 

Atomic force microscopy is finding more use in examination of membranes, but artifacts must be addressed, as was done by Bowen and Doneva [197], who noted changes in pore size and structure and used Fast Fourier Transform (FFT) filtering to show the true pore shape. Samples for AFM were prepared by attaching them to steel disks with double sided tape. These same authors used AFM to characterize ultrafiltration membranes [198, 199] and characterized the pore dimensions and quantified the interaction or adhesion of cellulose with two polymeric UF membranes. Atomic force microscopy was also used to characterize molecularly imprinted composite polyethersulfone membranes for quantification of the pore size and surface roughness [200]. 

Investigation of interfacial effects and interactions between biocompounds and transducer surfaces at the molecular and atomic levels by exploiting new methods of surface analysis (e,g scanning microscopy techniques, fast-atomic-bombardment mass spectrometry, laser-assisted mass spectrometry, time-of-flight secondary ion mass spectrometry, Fourier-transform infrared spectrometry, ellipsometry. X-ray photoelectron spectroscopy, and electron microscopy)... 

---