Dynamic Stabilization in 1su 1pg-Excited Nitrogen Clusters

R.Flesch,1 A.A.Pavlychev,2 J.J.Neville,3 J.Blumberg,1 M.Kuhlmann,1 W.Tappe,1 F.Senf,4 O.Schwarzkopf,4 A.P.Hitchcock,5 and E.Rühl 1

1 Fachbereich Physik,Universität,Osnabrück,Barbarastrasse 7,49069 Osnabrück, Germany

2 Institute ofPhysics,St.Petersburg State University St.Petersburg 198904, Russian Federation

3 Department of Chemistry, University of New Brunswick,P.O.Box 45222,Fredericton,NB,Canada E3B 6E2

4 BESSY GmbH, Albert-Einstein-Strasse 15,12489 Berlin,Germany

5 Department of Chemistry, McMaster University, Hamilton, Ontario Canada L8S 4M1

(Received 24 August 2000)

High-resolution 1s near-edge spectra of molecular nitrogen and variable size nitrogen clusters obained using monochromatic synchrotron radiation from the high brilliance BESSY-II storage ring faility are reported. The vibrationally resolved 1su ->1pg core-to-valence excitation band of clusters shows a distinct redshift of 6 (1) meV relative to the isolated molecule, but the vibrational structure and linewidths are essentially unchanged. This shift is assigned to dynamic stabilization of 1su ->1pg excited molecules in clusters, arising from the dynamic dipole moment generated by core-hole localization in the low-symmetry cluster field.This leads to changes in intermolecular interactions compared to the ground-state cluster.Such spectral shifts are expected to occur generally in molecular clusters and in the corresponding condensed phase.

DOI:10.1103/PhysRevLett.86.3767

PACS numbers:36.40.Mr,33.20.Rm