Exploring electron density distributions for the complete valence shell of cyclopentene using a binary (e,2e) spectrometer

The measurements of electron density distributions and binding-energy spectrum of the complete valence shell of cyclopentene (C5H8) using a binary (e,2e) electron momentum spectrometer are reported. The experimental momentum profiles of the valence orbitals are compared with the theoretical distributions calculated using Hartree-Fock and density-functional-theory (DFT) methods with various basis sets. The agreement between theory and experiment for the shape and intensity of the orbital electron momentum distributions is generally good. The DFT calculations employing B3LYP hybrid functional with a saturated and diffuse AUG-CC-PVTZ basis set provide the better descriptions of the experimental data. Some "turn up" effects in the low momentum region of the measured (e,2e) cross section compared with the calculations of 3a″, 2a″, and 3a′ orbitals could be mainly attributed to distorted-wave effects. The pole strengths of the main ionization peaks from the orbitals in the inner valence are estimated.