EGAS41 - Swansea University

41 st EGAS CP 40 Gdańsk 2009
Investigation of the 3 i 4 1 Π u states in Li 2 using polarisation
labelling spectroscopy
Z. Jȩdrzejewski-Szmek 1,∗ , P. Kowalczyk 1 , W. Jastrzȩbski 2 , A. Grochola 1
1 Institute of Experimental Physics, University of Warsaw, ul. Hoża 69, 00-681 Warszawa,
Polska
2 Institute of Physics, Polish Academy of Sciences, al. Lotników 32/46,
02-668 Warszawa, Polska
∗ Corresponding author: zbyszek@in.waw.pl
Absorption spectra of the 3 1 Π u and 4 1 Π u states of the lithium dimer were measured
— primarily 7 Li 2 , but also 7 Li 6 Li. Polarisation labelling spectroscopy was used to simplify
measured spectra, limiting visible transisitions to one or more progressions of PQR
triplets [1].
Assigned transitions are consistent with previous measurements [2], but span a much
greater range of rotational-vibrational quantum numbers. The positions of energy levels
were found to be heavily perturbed: by nearby Σ states, but also by the electrostatic
interaction between the two Π states.
A deperturbation analysis was performed by extending Inverted Perturbation Approach
with simultaneous treatment of two electronic states. The results of an attempt to
reproduce spectral measurements from a model with two potential wells and parameters
describing the electrostatic perturbation are shown.
Figure 1: Potential energy in the 3 1 Π u i 4 1 Π u states of the 7 Li 2 molecule.
References
[1] Theiss et al., Chemical Physics Letters 174, 128 (1990)
[2] Z. Jȩdrzejewski-Szmek et al., Chemical Physics Letters 444, 229 (2008)
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