Dear B. Sathyamoorthy

I think it is possible to study oxygen vacancy using Raman. First you have to make theoretical calculations using Gaussian 09 program before and after the vacancy and compare the results. Afterward search your experimental findings for the same.

In Raman every bond length and its strength are very important in deciding force constant which decides the Raman shift of a particular vibration between two atoms. If there is a vacancy, there must be a deduction or increase in bond length and hence, strength. This may give different value for Raman shift. I hope lattice dynamics calculation with and without vacancy using suitable software may help you I this regard.

Yes, Raman would help.