Adsorption interference microscopy

In a recent experimental study of the adsorption of methanol in a large crystal of CrAPO by interference microscopy, Lehmann et al. [36] observed that, even at equilibrium, the distribution of sorbate through the crystal is far from uniform. It seems clear that access is controlled lai ely by the defect structure and the growth planes of the crystal. This observation may provide a plausible explanation for the discrepancies observed between different diffusion measurements. The impact of the defect structure... 

Fig. 17 Transient concentration profiles in y-direction (i.e., along 8-ring channels) measured by interference microscopy for a adsorption and b desorption of methanol in a large crystal of ferrierite for pressure steps 5 -> 10 and 10 5 mbar. The form of the profiles shows that both surface resistance and internal diffusion (along the 8-ring chan-...

Keywords Diffusion Co- and Counterdiffusion Adsorption IR techniques Interference microscopy... 

Fig. 36 Intracrystalline concentration profiles of isobutane in silicalite-1 along the z direction during adsorption a,b profiles measured by interference microscopy c,d simulated profiles, assuming that the internal interfaces serve only as transport barriers. For the simnlated profiles the time nnit is 10 elementary diffnsion steps. The eqnilibrinm valnes of C(y, z) after the end of adsorption are eqnal to 1...

As schematically shown by Fig. 46a, ferrierite contains two mutually intersecting arrays of channels. In comparison with the strictly one-dimensional MOF crystals considered in the previous section, their analysis is additionally complicated by the existence of two rooflike parts on either side of the platelike main crystal body. It turned out, however, that these features did in no way complicate the method of analysis. Contrary to the MOFs, which required an additional activation step after each uptake experiment, methanol in ferrierite proved to be an ideal host-guest system, where one and the same crystal could alternately be subjected to adsorption and desorption without any perceptible change in the sorbate profiles. It were these special conditions under which interference microscopy could be developed to a technique of diffusion measurement in nanoporous materials of unprecedented power [63,65,70,71,88,89]. 

Fig. 50 Concentration profiles integrated over the z direction observed by interference microscopy during a methanol pressure step from 0 to 1 mbar. a Two-dimensional and b one-dimensional profiles in the crystal center along the x (fair spheres) and y (black spheres) directions. The times after onset of adsorption are indicated in b...

Fig. 29. (a) Ferrierite crystal with a two-dimensional pore structure utilized to determine spatially resolved concentration of methanol, (b) Intercrystalline concentration profiles measured during adsorption hy interference microscopy. Reprinted from 202, cop5rright 2006, with kind permission from American Chemical Society. 

Eden G J, Gao X and Weaver M J 1994 The adsorption of suiphate on goid(111) in acidic acqueous media Adiayer structurai interferences from infrared spectroscopy and scanning tunneiing microscopy J. Electroanal. Chem. 375 357-66... 

The tungsten (110) surface is one of the best studied of all surfaces, especially in field emission and field ion microscopy for many reasons. It is a very stable surface without surface reconstruction or phase transformation. It is also inert to contaminations. For the study of adatom-adatom interactions, it is a very smooth plane with the largest density of adsorption sites available of any W surface. Lesser restrictions are imposed on the adatom-adatom separation. As the surface is structurally very smooth, wave mechanical interference effects are least affected by the surface atomic structure. 

Fig. 10.11 Adsorption of 3LNPs with PKH26 on SKOV-3 cell membrane at pH 7.4 (a, b) and 6.0 (c, d) at 4°C observed with confocal scanning laser fluorescence microscopy. Differential interference contrast (a, c) and red fluorescence channel (b, d)...

As a consequence, researchers from different disciplines of the life sciences ask for efficient and sensitive techniques to characterize protein binding to and release from natural and artificial membranes. Native biological membranes are often substituted by artificial lipid bilayers bearing only a limifed number of components and rendering the experiment more simple, which permits the extraction of real quantitative information from binding experiments. Adsorption and desorption are characterized by rate constants that reflect the interaction potential between the protein and the membrane interface. Rate constants of adsorption and desorption can be quantified by means of sensitive optical techniques such as surface plasmon resonance spectroscopy (SPR), ellipsometry (ELL), reflection interference spectroscopy (RIfS), and total internal reflection fluorescence microscopy (TIRE), as well as acoustic/mechanical devices such as the quartz crystal microbalance (QCM)... 

Adsorption dynamics Ruorescence spectroscopy and microscopy (including immunofluorescence, total internal reflection fluorescence) Attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) Quartz crystal microbalance (Spectroscopic) eUipsometry Reflectometric interference spectroscopy... 

Commonly used spectroscopic or analytical techniques for characterizing surfaces and coating layers on porous silicon are Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy, energy dispersive X-ray spectrometry, fluorescence spectroscopy, UV-Vis absorption/reflectance spectroscopy, thin film optical interference spectroscopy, impedance spectroscopy, optical microscopy, scanning electron microscopy, transmission electron microscopy, atomic force microscopy, ellipsometry, nitrogen adsorption/desorp-tion analysis, and water contact angle. 

---