Have you considered using ATR-FTIR? This is an excellent method to use FTIR for inspecting thin surface coatings and interfaces between coating and substrate. ATR is an acronym for attenuated total reflectance. You will probably find something on Wikipedia. I would definitely try this before Raman, since the PVC features you are looking for will be visibel in an IR spectrum.

dear Amit Mishra;

in my opinion both are important to you

Fourier Transform-Infrared Spectroscopy (FTIR) measures the absorption of infrared radiation by the sample material versus wavelength. The infrared absorption bands identify molecular components and structures it usually used to find out the functional groups present in the material.

Raman Spectroscopy provides detailed information about chemical structure, phase and polymorphy, crystallinity and molecular interactions. It is based upon the interaction of light with the chemical bonds within a material.

It probes the chemical structure of a material and provides information about:

Chemical structure and identity

Phase and polymorphism

Intrinsic stress/strain

Contamination and impurity

the attached figure shows Raman spectra of some PVC-SWNT nanocomposites (detail showing the D and G lines of SWNTs).

I also had problems studying thin film coatings using FTIR. I did't have access to Raman. If you are intersted in mass deposition/density of your coating (over time) I had good experience with QCM-D technique (commercial Si-chips should be available). However, chemical bonds , ect. can't be assessed of course.