Scanning tunneling microscopy (STM) and noncontact atomic force microscopy have been used to follow the $1\times 1$ to $1\times 3$ phase transition of ${\mathrm{TiO}}_2\left(100\right)$. Two structural intermediates with $1\times 3$ symmetry are imaged in addition to the $1\times 1$ phase and the $1\times 3$ microfacet structure which has previously been imaged with STM. The results indicate that a series of discrete bond breaking steps are involved in the transition.

• Received 9 November 1998

DOI:https://doi.org/10.1103/PhysRevLett.82.5265