Isotope-induced partial localization of core electrons in the homonuclear molecule N2.
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.
Rolles
Daniel
D
Fritz-Haber-Institut der Max-Planck-Gesellschaft, 14195 Berlin, Germany.
Braune
Markus
M
Cvejanović
Slobodan
S
Gessner
Oliver
O
Hentges
Rainer
R
Korica
Sanja
S
Langer
Burkhard
B
Lischke
Toralf
T
Prümper
Georg
G
Reinköster
Axel
A
Viefhaus
Jens
J
Zimmermann
Björn
B
McKoy
Vincent
V
Becker
Uwe
U