EGAS41 - Swansea University

41 st EGAS CP 174 Gdańsk 2009
Interference effects in the resonant CO(1s −1 π ∗ , v)
excitation studied by the CO + (A–X) fluorescence
Ph.V. Demekhin 1∗ , I.D. Petrov 2 , V.L. Sukhorukov 2 , W. Kielich 1 , P. Reiss 1 ,
R. Hentges 1 , I. Haar 1 , H. Schmoranzer 3 , A. Ehresmann 1
1 Institut für Physik, Universität Kassel, D-34132, Kassel, Germany
2 Rostov State University of TC, 344038, Rostov-on-Don, Russia
3 Technische Universität Kaiserslautern, D-67653 Kaiserslautern, Germany
∗ Corresponding author: ehresmann@physik.uni-kassel.de
Resonant Auger decay is one of the most suitable prototype for studying quantum mechanical
interferences. The strong interferences between different transition amplitudes
of resonant photoionization and weak direct photoionization, known as electronic states
interference (ESI), was recently found in the resonant Auger decay of the Kr 3d 9 np states
[1]. The interference between transition amplitudes via different vibrational levels of the
same electronic state, known as lifetime vibrational interference (LVI), is another type
of quantum mechanical, which can be studied by the inner-shell resonance excitation of
molecules [2].
In the present work we report a joint theoretical and experimental study of the ESI and
LVI in the 1s −1 π ∗ (v) resonant excitation and subsequent Auger decay in randomly oriented
CO molecules. For this purpose, polarization analysis of the A 2 Π(v ′ ) → X 2 Σ + (v ′′ )
fluorescence in the CO + ion excited in the vicinity of the C ∗ O and CO ∗ resonances has
been performed. The energy dependencies of the angular distribution parameters for the
A 2 Π(v ′ ) photoelectrons and for the subsequent A 2 Π(v ′ ) → X 2 Σ + (v ′′ ) fluorescence in the
vicinity of the C ∗ O and CO ∗ resonances are predicted theoretically. These energy dependencies
are due to the electronic states interference and lifetime vibrational interference.
The interference has a long energy range character and is important even in case of the
C ∗ O excitation.
The present theoretical results are verified at the U49/2 PGM1 beamline, BESSY
II, Berlin, by means of the photon-induced fluorescence spectroscopy (PIFS) [3]. The
resolution of the linearly polarized exciting synchrotron radiation was set to 75 meV at
289 eV for the C ∗ O resonance and to 135 meV at 535 eV for the CO ∗ resonance in order
to be in the Raman regime for core excitations. Polarization analysis of the dispersed
A 2 Π(v ′ ) → X 2 Σ + (v ′′ ) fluorescence has been performed in the visible spectral range from
378 nm to 578 nm with the resolution of about 0.5 nm using a Wollaston prism.
References
[1] B.M. Lagutin, et al., Phys. Rev. Lett. 90, 073001 (2003)
[2] F.K. Gel’mukhanov, H. Ågren, Phys. Rep. 312, 87 (1999)
[3] H. Schmoranzer, et al., Nucl. Instr. Meth. Phys. Res. A 467-468, 1526 (2001)
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