title: Isotope-induced partial localization of core electrons in the homonuclear molecule N2.
abstract: Because of inversion symmetry and particle exchange, all constituents of homonuclear diatomic molecules are in a quantum mechanically non-local coherent state; this includes the nuclei and deep-lying core electrons. Hence, the molecular photoemission can be regarded as a natural double-slit experiment: coherent electron emission originates from two identical sites, and should give rise to characteristic interference patterns. However, the quantum coherence is obscured if the two possible symmetry states of the electronic wavefunction ('gerade' and 'ungerade') are degenerate; the sum of the two exactly resembles the distinguishable, incoherent emission from two localized core sites. Here we observe the coherence of core electrons in N(2) through a direct measurement of the interference exhibited in their emission. We also explore the gradual transition to a symmetry-broken system of localized electrons by comparing different isotope-substituted species--a phenomenon analogous to the acquisition of partial 'which-way' information in macroscopic double-slit experiments.
authors.affiliation: Fritz-Haber-Institut der Max-Planck-Gesellschaft, 14195 Berlin, Germany.
authors.forename: Daniel
authors.initials: D
authors.lastname: Rolles
authors.forename: Markus
authors.initials: M
authors.lastname: Braune
authors.forename: Slobodan
authors.initials: S
authors.lastname: Cvejanović
authors.forename: Oliver
authors.initials: O
authors.lastname: Gessner
authors.forename: Rainer
authors.initials: R
authors.lastname: Hentges
authors.forename: Sanja
authors.initials: S
authors.lastname: Korica
authors.forename: Burkhard
authors.initials: B
authors.lastname: Langer
authors.forename: Toralf
authors.initials: T
authors.lastname: Lischke
authors.forename: Georg
authors.initials: G
authors.lastname: Prümper
authors.forename: Axel
authors.initials: A
authors.lastname: Reinköster
authors.forename: Jens
authors.initials: J
authors.lastname: Viefhaus
authors.forename: Björn
authors.initials: B
authors.lastname: Zimmermann
authors.forename: Vincent
authors.initials: V
authors.lastname: McKoy
authors.forename: Uwe
authors.initials: U
authors.lastname: Becker