Comparison of the Near-Field Spectroscopic Methods

Spectroscopic imaging with nanometer spatial resolution is a very attractive proposition. Having full spectroscopic information available at every pixel is also crucial for obtaining simultaneous chemical information for unknown, heterogeneous samples, or when following transient events. Detailed information from small frequency shifts (not available from fixed-frequency imaging) can also be obtained. 

East spectroscopic imaging will further facilitate the high-throughput investigation 

Sensitivity Poor Single molecule level(gap-mode TERS) -100 molecules (estimated from its spatial resolution) 

Sample topography No requirement No requirement (Flat sample is required for gap-mode TERS) Flat sample surface 

Spectral range Full spectrum (for Raman) Full spectrum Single wavelength 

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