  We have performed scanning tunneling microscopy/spectroscopy (STM/STS) study
and first-principles calculations to investigate the atomic structure and
electronic properties of silicon nanoribbons (SiNRs) grown on Ag(110). Despite
of the extensive research on SiNRs in the last decades, its atomic structure is
still not fully understood so far. In this report we determine that the
structure of SiNRs/Ag(110) is armchair silicene nanoribbon with reconstructed
edges. Meanwhile, pronounced quantum well states (QWS) in SiNRs were observed
and their energy spectrum was systematically measured. The QWS are due to the
confinement of quasiparticles perpendicular to the nanoribbon and can be well
explained by the theory of one-dimensional (1D) 'particle-in-a-box' model in
quantum mechanics.
