Geometrical and Chemical Structure of Fused Silica Surface

1 Geometrical and Chemical Structure of Fused Silica Surface 

Roughness of surfaces can be defined as the geometric morphology at suprananome-ter scale. It can be quantitatively characterized by setting a mean surface level with 

A great general interest in the sorption technologies with silica adsorbents, as well as their widespread use, have motivated numerous experimental and theoretical studies of the structure and chemistry of these materials. In particular, it is true for the investigations of surfaces of amorphous silica, both its bulk and high specific area varieties. Several books and monographs are fully or partially concerned with this topic [33-36]. Below, we shall selectively cite some more recent journal publications they contain references to more sources. 

Surfaces of real commercial fused-silica chromatographic columns and wafers have recently been repeatedly visualized by SEM, AFM, and STM techniques. The imaging showed that the surfaces commonly feature scratches, digs, pits, nodules, foreign inclusions, eventual marks from polishing and machining, as well as attached particles of dust. 

The inner surface of the fused silica tubes (typically of 3 mm i.d.) which were used in the TC experiments with TAEs was inspected [37] by SEM. The tubes came from different manufacturers and batches. Sample results are presented in Fig. 5.6. Some of the observed morphology on the micrometer scale was unexpected and even exotic (shots numbers 1 to 3). The statistics of such peculiarities were not quantitatively measured, but most parts of the surfaces seemed to be smoother (shots numbers 4 to 6), with roughness of a few tens of nanometers the flatness on this scale could be significantly improved by chemical etching and subsequent annealing of the tubes at high temperatures. 

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