SPM: SUPERMOLECULAR STRUCTURE OF SHUNGITE

Yevgeny Golubev

Institute of Geology of Russian Academy of Sciences, 54,Pervomayskaya st., 167610, Syktyvkar, Russia,
e-mail:rmin@geo.komi.ru.

Noncrystalline carbon from shungite rocks (shungite occurrences in the north-western part of lake Onega, Karelia) has characteristic globular structure [1]. Shungites with high proportions of carbon in their composition (carbon accounts for 98% in vein shungites) are chemically inert and metastable, which makes them suitable for imaging by means of scanning probe microscopy (SPM) [2]. SPM techniques are widely used for examining surface structures of solids, because they imaging in air and fluids, which is essential for metastable substances. SPM procedure for examining surface morphostructures is relatively simpler than, for example, REM.

Highly-carbonaceous vein shungite from various deposits (Maxovo (M), Shunga (S), Tchebolaksha (T), Zazhogino (Z)) was studied by scanning tunneling microscopy (STM) and atomic force microscopy (AFM). The surface was scanned with a Burleigh Personal STM ARIS 2200 and Burleigh Personal AFM ARIS 3500. All STM images were obtained using PtIr tips, AFM images, with standard silicon cantilever (pyramid-shaped, radius at end 10 nm). The surfaces were split in air. STM and AFM images show a globular structure for M, S, and Z shungites. The globules tend to have a similar orientation. Statistical analysis of linear dimensions of elements in shungite structure was peformed based on the STM and AFM images.

[1] V.V.Kovalevsky, Dissertation for the degree of candidate of geol.-min. sciences. Moscow: Institute of Crystallography USSR Acad. Sci. (1986).
[2] N.P.Yushkin, Doklady Akademii Nauk. Geologiya. 337 (1994) 800-803.