Determination of Absolute Coverages for Small Aliphatic Alcohols on TiO2(110)
The absolute coverages of water and small aliphatic alcohols (C1-C4) were determined on TiO{sub 2}(110) using a combination of temperature programmed desorption and liquid nitrogen cooled quartz crystal microbalance measurements. The absolute saturation coverages of water on Ti{sup 4+} and bridging oxygen (O{sub b}) sites are found to be equal to 1 monolayer with respect to the number of Ti{sup 4+} and/or O{sub b} sites (1 ML {triple_bond} 5.2 x 10{sup 14} cm{sup 2}) in a good agreement with prior studies. The saturation coverages of primary alcohols on Ti{sup 4+} sites are found to be approximately constant and equal to 0.77 ML. This indicates that the increasing length of the alkyl chains does not contribute to additional steric hindrance. Additional steric hindrance is observed with increasing number of chains as shown for secondary alcohols and tertiary t-butanol where the coverage decreases to 0.62 and 0.44 ML, respectively. On O{sub b} rows, a monotonic decrease of the alcohol coverage is observed for both increasing length of the alkyl chains and the chain number.