Atomic Force Microscopy Determination of the Molecular Orientation and Array Structure of a Pyridine Adlayer on Heulandite(010) Adsorbed from Its Aqueous Solution

Abstract

For the first time the array structure of liquid-phase-adsorbed aromatics on a zeolite surface was determined, and the molecular orientation within the adsorbed phase was estimated. Pyridine molecules adsorbed on a cleaved heulandite(010) surface from an aqueous solution were imaged with a contact-mode atomic force microscope. The adsorbed pyridine molecules formed a well-ordered two-dimensional (2D) hexagonal array on the surface, with the rhombic unit cell dimension being 0.55 nm. The molecular plane is found to be tilted, with the estimated tilt angle being ca. 43°to the surface. The ring plane also makes an estimated angle of ca. 20°with respect to one of the 2D lattice vectors of the adsorbed pyridine unit cell.

Adlayer formation of DNA base cytosine over natural zeolite heulandite(010) surface by AFM

“…We would like to note that the adlayer structure of cytosine, a pyrimidine base, is quite similar to that of a pyridine base adsorbed on heulandite(010) [2]. Both of them show hexagonal structures, and both of them are incommensurate with the substrate lattice.…”

“…They crystallize into various crystallographic structures, and hence there are numerous natural as well as synthetic zeolites. They are found to adsorb various chemical species and to catalyze various reactions, and are extensively used as adsorbents and catalysts in the chemical industry.Recently we successfully obtained atom-resolved AFM images of natural zeolite surfaces, stilbite(010) and heulandite(010), and in situ molecular images of liquid-phaseadsorbed pyridine and picolines (pyridine bases) on these surfaces [1][2][3][4]. From these AFM data we were able to determine the array and orientation structures of the adsorbed molecules.…”

“…Recently we successfully obtained atom-resolved AFM images of natural zeolite surfaces, stilbite(010) and heulandite(010), and in situ molecular images of liquid-phaseadsorbed pyridine and picolines (pyridine bases) on these surfaces [1][2][3][4]. From these AFM data we were able to determine the array and orientation structures of the adsorbed molecules.…”

Epitaxy and Molecular Organization on Solid Substrates

“…In all cases the Pc films exhibit structures reflecting weakly-interacting molecules with monolayer structures that do not resemble native bulk crystal structures. Other examples of overlayers dominated by overlayer-substrate energy include para-hexaphenyl on GaAs(001), [117] tetrathiafulvalene tetracyanoquinodimethane (TTF-TCNQ) on KCl, [118] protoporphyrins on HOPG, [119] pyridine on heulandite, [120] tetra(4-pyridyl)porphyrin [121] and tetraphenylporphyrin [122] on KCl.…”

Simulation of Atomic Force Microscopy Images of Cleaved Mica Surfaces

“…The obtained image is not a "true" atomic image, however, since it consists of interferences among the forces felt by an individual apex atom, as exemplified by an appearance of a false atom at a point defect site. 14,18 Recent contact-mode AFM observations tend to employ lower applied forces on the order of nanonewtons 5,22 in order to avoid damages on both the tip apex and sample surfaces, resulting in well-resolved surface atom images.…”