Surface-sensitive molecular information on polymers from UV-resonance Raman spectroscopy

Ultraviolet resonance Raman spectroscopy (UV-RRS) has been applied to a series of samples of poly(ethylene 2,6-naphthalene dicarboxylate) (PEN) and poly(ethylene terephthalate) (PET) of varying thickness. The spectra demonstrate that under resonance conditions, when absorption is very strong, only a very thin top layer of the sample is probed (hundreds of nanometers range). This allows probing molecular vibrational spectra of the top layer of the sample, with a surface-resolution at least an order of magnitude better than in the case of normal non-resonance Raman spectroscopy and using a microscope.