Hello everyone,

I need to ask a question about the RAIRs spectrum of carboranethiols SAMs on Au films. I've added the absorption spectra at 80 and 85 degrees for two SAMs on Au surfaces in the attached file. While M1-COOH SAMs give a good spectrum, absorption spectra of M9-COOH are very irregular and seem noisy. But I know our system has a very high signal/noise ratio for other films. I know M9-COOH molecules constitute very irregular surfaces (molecules are arranged arbitrarily (non-isotropically) in the film according to XPS, AFM, and Contact angle results ). Accordingly, how can we explain this irregular structure of the M9-COOH spectra? Can we say irregular films cause irregular absorption spectra? Can we find any article about it?

Many thanks to everyone who has helped in advance.