Butyrophenone on O-TiO2(110): One-Dimensional Motion in a Weakly Confined Potential Well

We demonstrate the one-dimensional confinement of weakly bound butyrophenone molecules between strongly bound complexes formed via reaction with oxygen on TiO2(110). Butyrophenone weakly bound to Ti rows through the carbonyl oxygen diffuses freely in one dimension along the rows even at 55 K, persisting for many minutes before hopping out of the 1-D well. Quantitative analysis yields an estimate of the migration barrier of 0.11 eV and a frequency factor of 6.5 × 109 Hz. These studies demonstrate that weakly bound organic molecules can be confined on a surface by creating molecular barriers, potentially altering their assembly.