11:00-12:00
Optical Spectroscopy and Microscopy at the Ultimate Spatial Limit
Dr. Chi CHEN (former student at Wilson Ho Group)
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Photon spectroscopy and imaging at sub-ﾅngstrom resolution are
achieved by integrating a scanning tunneling microscope (STM) with the
optical
detection system. Optical properties of a single molecule and an
atomic nanostructure in both spectral and spatial domains are
presented. First,
ring-like emission patterns from a single magnesium porphine (MgP) are
imaged with distinct submolecular variations. In addition, vibronically
resolved spectroscopy and photon images reveal two orthogonal vibronic
progressions associated with different normal modes. Second, spatial
variations in the light emission are observed along atomic silver
chains (Ag1 to Ag10) at different photon energy. The number and
positions of
emission maxima correspond to the number and positions of nodes in the
dI/dV images. This spatial distribution of radiative transitions between
electronic states demonstrates the Fermi's golden rule in real space.
These two experiments manifest "textbook" results which not only lead to
direct visualization of quantum mechanics but also open a new
dimension to investigate optical phenomena at the ultimate spatial
limit.
