Noble gas clusters in carbon nanopores

Abstract

Low temperature high-energy electron diffraction study of size-dependent structures and growth mechanisms of neon and argon nanoclusters inside multiporous 'amorphous' carbon as well as theoretical consideration of cluster energetics with emphasis on shape optimization are presented. Multiply twinned particles (MTPs) such as icosahedra and decahedra (with fivefold symmetry) for small clusters are shown to be dominant. Applied analysis was based on the comparison of experimental and calculated intensities with the help of the R-factor minimization procedure. The new method is applicable not only to structural studies of clusters grown in pores but also for pores characterization and can also be used in the analysis of the wide group of objects which undergo the growth typical of confined geometry.

Neon in carbon nanopores: wetting, growth mechanisms, and cluster structures

“…The so-called schwartzites [5,6] formed by negatively curved graphitic sheets are permitted by interconnected channels and can be considered as a porous matrix, which may be filled with different substances under certain conditions. Clusters grown inside pores obey the growth mechanisms typical of confined geometry and demonstrate the absolute prevalence of structures with the five-fold symmetry [7][8][9]. Such structures were earlier observed in essentially different experiments [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21] with the only one common feature, i.e., the limited number of interacting atoms during growth.…”

“…Basically the applied procedure was typical of the preparation of «amorphous» carbon films, which are widely used in electron microscopy and diffraction as supporting substrates mainly because of the absence of distinct diffraction peaks from such films superimposed on lines of the material deposited upon substrates. However, it was noticed [5,8,9] that carbon films prepared in such a way also exhibit several important features, which characterize them as a porous matrix with very fine channels. One of them is the absence of the (broad) peak corresponding to distances between basal planes of graphite [8] (see also Fig.…”

“…However, it was noticed [5,8,9] that carbon films prepared in such a way also exhibit several important features, which characterize them as a porous matrix with very fine channels. One of them is the absence of the (broad) peak corresponding to distances between basal planes of graphite [8] (see also Fig. 1) while other characteristic peaks were observed and evidenced (allowing for the radial distribution functions [5,8]) in favor of negatively curved graphitic sheets forming the porous matrix.…”

“…One of them is the absence of the (broad) peak corresponding to distances between basal planes of graphite [8] (see also Fig. 1) while other characteristic peaks were observed and evidenced (allowing for the radial distribution functions [5,8]) in favor of negatively curved graphitic sheets forming the porous matrix. Several independent observations confirmed the essential difference of such substrates from (e.g.)…”

“…Diffractograms ( Fig. 1) were analyzed using simulations, which were made in a similar way as described pre- viously [7][8][9], i.e., on the basis of the assumption of a wide variety of possible structures and sizes of clusters (Fig. 2).…”