Vibrationally resolved photoelectron spectra of the carbon 1s and nitrogen 1s shells in hydrogen cyanide Original Research Article

Vibrational structures of the C1s and N1s photoelectron spectra of gas-phase HCN have been investigated using monochromated third-generation synchrotron radiation. Both spectra exhibit resolved fine structure associated with several vibrationally excited states. In the C1s spectrum a single vibrational progression is observed, while the N1s spectrum is more complex. High-level ab initio calculations were performed to simulate the spectra and the agreement with the experimental results is good. Based on the calculations, the C1s ionisation is found to induce vibrations solely in the CN stretching mode with an energy of 280 meV, while the N1s ionisation generates vibrations also in the CH stretching mode with an energy of about 387 meV, as well as combinations of these two modes.