From Double Slit Interference to Structural information in simple hydrocarbon

Abstract : Interferences in coherent emission of photoelectrons from two equivalent atomic centers in a molecule are the microscopic analogous of the celebrated Young's double-slit experiment [1-10]. By considering inner-valence shell ionization in the series of simple hydrocarbons C2H2, C2H4 and C2H6, we show that double-slit interference is widespread, and has built-in quantitative information on geometry, orbital composition and many-body effects. A theoretical and experimental study is presented over the photon energy range 70-700 eV. A strong dependence of the oscillation period upon the C-C distance is observed, which can be used to determine bond lengths between selected pairs of equivalent atoms with at least 0.01 Å accuracy. Furthermore, we show that the observed oscillations are directly informative of the nature and atomic composition of the inner-valence molecular orbitals, and observed ratios are quantitative measure of elusive many-body effects. The technique and analysis can be immediately extended to a large class of compounds.