  One-dimensional (1D) stripe structures with a periodicity of 1.3 nm are
formed by introduction of stacking fault arrays into a Ag thin film. The
surface states of such striped Ag thin films are studied using a low
temperature scanning tunneling microscope. Standing waves running in the
longitudinal direction and characteristic spectral peaks are observed by
differential conductance (dI/dV) measurements, revealing the presence of 1D
states on the surface stripes. Their formation can be attributed to quantum
confinement of Ag(111) surface states into a stripe by stacking faults. To
quantify the degree of confinement, the effective potential barrier at the
stacking fault for Ag(111) surface states is estimated from independent
measurements. A single quantum well model with the effective potential barrier
can reproduce the main features of dI/dV spectra on stripes, while a
Kronig-Penney model fails to do so. Thus the present system should be viewed as
decoupled 1D states on individual stripes rather than as anisotropic 2D Bloch
states extending over a stripe array.
