Tip-enhanced Raman spectroscopy and microscopy are performed on a single nitrogen atom, carbon monoxide, pyridine, and benzene adsorbed on the Cu(100) surface. As the complexity of system ranging from an atomic vibrator to polyatomic molecules increases, the collective information gained from individual experiments elucidates the governing mechanism of Raman scattering in the atomistic near-field from different angles. Rich physics observed from above-mentioned systems such as dielectric screening, concomitant electromagnetic and chemical enhancement, Stark shift, dehydrogenation, and distortion and recovery of vibrational information will be discussed.
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