Fluoroalkyl Iodide Photodecomposition on Diamond(100)-An Efficient Route to theFluorination of Diamond Surfaces

摘要

The photodecomposition of CF3I and C4F9I overlayers at 119K on diamond (100)surfaces has been shown to be an efficient route to fluorination of the diamond surface. X-ray photoelectron spectroscopy (XPS) has been used for photoactivation as well as for studies of the following processes: the photodecomposition of the fluoroalkyl iodide molecules: the attachment of the photofragments to the diamond surface; and the thermal decomposition of the fluoroalkyl ligands. Chemisorbed CF3 groups on diamond (100) decompose by 300 K whereas C4F9 groups decompose over the temperature range of 300 K to approx. 700 K. Both of these thermal decomposition processes produce surface C-F bonds on the diamond surface which thermally decompose over a wide temperature range extending up to 1500 K. Hydrogen passivation of the diamond surface is ineffective in preventing free radical attack from the photodissociated products of the fluoroalkyl iodides. The use of photoactivation of fluoroalkyl iodides for the fluorination of diamond surfaces provides a convenient route compared to other methods involving the direct production of atomic F, molecular fluorine, XeF2, and F containing plasmas.