Phase Segregation in the Mixed Alkyl Thiol Self‐assembled Monolayers on a Gold Surface at a High Incubation Temperature in a Sealed Container

<jats:p>Self‐assembled monolayers (<jats:styled-content style="fixed-case">SAMs</jats:styled-content>) of mixed 1‐octanethiol (<jats:styled-content style="fixed-case">OT</jats:styled-content>) and 1‐decanethiol (<jats:styled-content style="fixed-case">DT</jats:styled-content>) that were formed on gold substrates at a high incubation temperature in a sealed container were characterized using scanning tunneling microscopy (<jats:styled-content style="fixed-case">STM</jats:styled-content>) and X‐ray photoelectron spectroscopy (<jats:styled-content style="fixed-case">XPS</jats:styled-content>). In mixed‐composition monolayer films, self‐assembly of the mixture could induce phase separation into discrete molecular domains at higher incubation temperatures. Mixtures of the alkanethiol molecules affected the domain size, defect density, packing density, and binding features of the resultant <jats:styled-content style="fixed-case">SAMs</jats:styled-content> prepared on gold substrates. Single‐molecule‐resolved <jats:styled-content style="fixed-case">STM</jats:styled-content> images of mixed <jats:styled-content style="fixed-case">SAMs</jats:styled-content> revealed both <jats:italic>c</jats:italic>(4 × 2) − ns (non‐shifted) for <jats:styled-content style="fixed-case">DT</jats:styled-content> and <jats:italic>c</jats:italic>(4 × 2) − s (shifted) for <jats:styled-content style="fixed-case">OT</jats:styled-content> domains. For the mixed <jats:styled-content style="fixed-case">SAMs</jats:styled-content>, the peak <jats:styled-content style="fixed-case">S2</jats:styled-content> (<jats:styled-content style="fixed-case">XPS</jats:styled-content>) increased in intensity relative to the peak <jats:styled-content style="fixed-case">S1</jats:styled-content>, reflecting significant modifications in the binding characteristics of the thiols and surface roughness upon mixing.</jats:p>