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MO: Molekülphysik

MO 11: VUV Spectroscopy

MO 11.4: Vortrag

Montag, 13. März 2006, 11:45–12:00, H10

Accidental predissociation of the N₂⁺(C ²Σ_u⁺) state observed in the C ²Σ_u⁺− X ²Σ_g⁺ fluorescence after vibrational selective excitation of the 1s⁻¹π^* resonance — •L Werner¹, S Klumpp¹, A Ehresmann¹, Ph Demekhin^2,3, M Lemeshko², V Sukhorukov^2,3, K-H Schartner⁴, and H Schmoranzer³ — ¹Institute of Physics, University of Kassel, D-34132 Kassel — ²Rostov State University, 344038 Rostov-on-Don — ³TU Kaiserslautern , D-67653 Kaiserslautern — ⁴Justus-Liebig-University, D-35392 Giessen

N₂⁺ (C−X) fluorescence was investigated by photon-induced fluorescence spectroscopy after vibrational selective excitation of the 1s⁻¹π^* resonance in the fluorescence wavelength range between 135nm - 205nm. One peculiarity of the N₂⁺(C−X) fluorescence after direct excitation of the N₂⁺(C) state is the strong intensity decrease for bands with v′ ≥ 3. In a first experiment only band sequences with Δ v=const. could be observed but with an improved fluorescence resolution of 0.1nm it was possible to observe single fluorescence bands with Δ v=-6/-7. Calculations predict a maximum of the fluorescence intensity at Δ v=−5 if accidental predissociation is taken into account. With a very narrow fluorescence resolution of about 0.1nm it was even possible to resolve individual vibrational bands. Observed fluorescence intensities for the individual vibrational sequences of the C-X transition and measured cross sections of the C-X fluorescence for vibrational sequences were compared to calculations with taking into account accidental predissociation and molecular rotation. The calculated intensities and describe well the shape of both individual vibrational bands and the whole band system.