The oscillator strengths for C1s and O1s excitation of some saturated and unsaturated organic alcohols, acids and esters

Abstract

Electron energy loss Spectroscopy (ISEELS) under dipole scattering conditions is used to obtain the carbon and oxygen K-shell oscillator strength spectra of methanol (CH3OH), propanol (CH3CH2CH2OH), propenol (CH2=CHCH2OH), propargyl alcohol (HC≡CCH2OH), propanoic acid (CH3CH2COOH), acrylic acid (CH2=CHCOOH) and propiolic acid (HC≡CCOOH). A detailed interpretation of these spectra is presented, along with a comparison with the NEXAFS spectra of multilayers of these molecules adsorbed on a Si(111) surface, as recently reported by Outka et al. (Surf. Sci., 185 (1987) 53). Good agreement is found between the multilayer NEXAFS and the gas phase ISEEL spectra, except for the carboxylic acids which differ dramatically in the discrete portion of the O1s spectrum. Possible origins for this difference are discussed. The C1s and O1s spectra of methyl formate (HCOOCH3) are also reported and interpreted in comparison with the spectra of formic acid and methanol.