LOW-COVERAGE STRUCTURE OF TETRAMETHYLTIN ADSORBED ON GRAPHITE

Submonolayers of protonated and deuterated tetramethyltin on exfoliate d graphite have been investigated with both X-ray and neutron diffract ion. At coverages theta < 0.8 ML, Sn(CH3)(4) on graphite forms a unit cell containing seven molecules in the tripod-down configuration. Slig ht differences between the lattice parameters of the protonated and th e deuterated adsorbate were found [a= 6.75 Angstrom, b = 44.2 Angstrom , gamma =113.5 degrees for Sn(CH3)(4) and a = 6.74 Angstrom, b = 44.5 Angstrom, gamma =114.0 degrees in the case of Sn(CD3)(4)]. The adsorba te structure is incommensurate with the graphite substrate and has lig ht domain walls. (C) 1998 Elsevier Science B.V. All rights reserved.