Identification of CH resonances in the K-shell excitation spectra of gas-phase, chemisorbed, and polymeric hydrocarbons

We demonstrate the existence and angular dependence of CH resonances in the carbon K-shell excitation spectra of hydrocarbons. Near-edge x-ray-absorption fine-structure spectra of oriented polyethylene chains exhibit pronounced resonances which are associated with CC and CH bonds as determined from their angular dependence and from X multiple-scattering calculations. The presence of CH resonances is also found in K-shell excitation spectra of free ethylene and ethylene chemisorbed on various metal surfaces. © 1987 The American Physical Society.