Hannover 2013 – wissenschaftliches Programm
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A: Fachverband Atomphysik
A 4: Cluster (with MO)
A 4.1: Vortrag
Montag, 18. März 2013, 11:00–11:15, F 102
Vibrational Spectroscopy of the Atmospherically Relevant Clusters NO3-(HNO3)m(H2O)n — •Nadja Heine1, Tara Yacovitch2, Claudia Brieger1, Torsten Wende1, Christian Hock2, Knut Asmis1, and Dan Newmark2 — 1Fritz-Haber-Institut der MPG, Berlin — 2University of California, Berkeley, California
Ions influence various chemical and physical processes in the atmosphere, such as the electrical conductivity and the formation of polar stratospheric clouds. They also play a critical role in aerosol formation through ion nucleation. Among the most abundant anions in the troposphere and stratosphere is nitrate (NO3-) and clusters of these ions with nitric acid and water. In order to understand the chemical and physical properties of these anionic clusters, as well as to test the structural predictions from previous computational studies, experimental information on the cluster structure is required. Here, we present first infrared multiple photon dissociation (IRMPD) spectra of NO3-(HNO3)m(H2O)n measured with the infrared free electron laser FELIX in the fingerprint region (550-1800cm-1), directly probing the NO-stretching and -bending modes. The assignment of the spectra is aided by electronic structure calculations. The IRMPD spectrum of m=1/n=0 is distinctly different from all other spectra exhibiting a strong absorption at 813cm-1, which we attribute to a strongly bound shared proton in-between two nitrate ions, and lacking the characteristic H-O-N bending mode absorption close to 1650cm-1. Addition of at least one nitric acid molecule or water breaks the symmetry of this arrangement.