[puccalie]

FTIR is known as one of the very usefull method to analyse the composition, and structure of organic material. When I read journal related to the transition metal oxide such as SiO2, some researcher use FTIR to predict the vibrational of Si-O-Si molecule.

I tried to find any literature or data based providing clear explanation for this. Is there is any specific calculation required to analyse the vibration peak and location for the metal oxide bond?

Thank you for helping..

[GCT]

Are you trying to identify certain peaks to the modes of vibration?  You aren't being very clear about what you're asking.  You can associate certain peaks to the particular modes of vibration by analyzing the rotational fine spectra for each region of vibration.  Using the moment of inertia, you can determine the spacings, by using the determined value of the rotational constant, however this is with the assumption that they are uniform for the levels in question.

[puccalie]

Yes, I`d like to identify the peak from FTIR spectra. I wonder whether there is database for FTIR peak regarding to Si-O-Si or Si-O-H.. I found there is many literature mentioning the peak for organic, for example: OH occurs at 3550 - 3200 cm-1. But I can not found the data base for the oxide .. Is there a handbook for this ? I have no clue what to do ... thank you for helping..

[Dan]

The geometry of a complex affects the number of IR active vibrational modes. By carrying out a full vibrational analysis of a proposed structure, one can determine the number of IR active (and Raman active) vibrational modes. This indicates the number of bands that will be seen in the IR spectrum (and Raman spectrum). By comparing the experimentally obtained IR spectrum (and Raman spectrum) with the result obtained for the analysis, one can determine whether or not the proposed geometry is correct - it is trial and error.

For structure determination in this way, IR and Raman spectroscopy are used to compliment each other because a particular geometry will give a particular number of IR and Raman bands, a particular numer of which will be coincident. It will also determine the number of polarised Raman bands.

Books:

JM Hollas - Modern Spectroscopy
K Nakamodo - Infrared and Raman spectroscopy in inorganic and coordination compounds