AVS 46th International Symposium
    Surface Science Division Friday Sessions
       Session SS3+EM-FrM

Paper SS3+EM-FrM6
Reactivity of Diamond (100) towards Cycloaddition Chemistry

Friday, October 29, 1999, 10:00 am, Room 604

Session: Reactions on Semiconductors
Presenter: G.T. Wang, Stanford University
Authors: G.T. Wang, Stanford University
S.F. Bent, Stanford University
J.S. Hovis, University of Wisconsin, Madison
R.J. Hamers, University of Wisconsin, Madison
J.N. Russell, Jr., Naval Research Laboratory
J.E. Butler, Naval Research Laboratory
M.P. D'Evelyn, General Electric
Correspondent: Click to Email
Diamond has a number of extreme material properties that make it an ideal candidate for a wide range of applications, including electronic devices, electron emitters, multispectral windows, and heat sinks. Similar to Si(100) and Ge(100), the diamond (100) surface undergoes a 2x1 reconstruction in which pairs of atoms are bonded into dimers via a strong sigma bond and a partial pi bond. Recent studies on 2x1 reconstructed Si(100) and Ge(100) have shown that the pi bond of the surface dimers can react with unsaturated hydrocarbons via [2+2] and [4+2] (Diels-Alder) cycloaddition reactions, forming covalently attached ring structures. In this study we investigate the viability of the diamond (100) surface to undergo cycloaddition reactions with cyclopentene and 1,3-butadiene using multiple internal reflection infrared spectroscopy and ab initio quantum chemistry calculations. While cyclopentene can react with the surface only via a [2+2] cycloaddition (which is formally forbidden for concerted reactions by symmetry considerations), 1,3-butadiene can potentially react via a [2+2] or [4+2] cycloaddition due to its conjugated double bond. It was found that both cyclopentene and 1,3-butadiene reacted with the diamond (100) surface at room temperature, although significantly larger exposures of cyclopentene were required. The greater reactivity of 1,3-butadiene versus cyclopentene may be attributable to 1,3-butadiene bonding via a lower-barrier [4+2] pathway not available to cyclopentene. Comparison of cycloaddition reactivity on diamond (100) versus Si(100) and Ge(100) provides insight into the mechanism of these reactions on semiconductor surfaces. These results also demonstrate the viability of organic synthetic routes for modifying the diamond surface.