The $A^1{\Sigma }_u^{+}$ + (1)${}^1{\Pi }_u$ system of Mg${}_2$

Abstract

The $A^1{\Sigma }_u^{+}$ - $X^1{\Sigma }_g^{+}$ UV spectrum of Mg${}_2$ has been investigated with high resolution employing Fourier-transform spectroscopy and laser excitation. Computer simulation and fit of line positions to the overlapping structures in the spectra yield precise transition frequencies. Starting with the well characterized ground state $X^1{\Sigma }_g^{+}$ from former work we derived excited energy levels and report on the evaluation of the $A^1{\Sigma }_u^{+}$ excited state, which is found to interact with another electronic state, which we identify as the lower part of the (1)${}^1{\Pi }_u$ state. A coupled channels fit to the level energies of the upper state yields a reliable potential energy curve for the $A^1{\Sigma }_u^{+}$ for the range of vibrational levels 1 $\le$ $v^{\prime }$ $\le$ 46. A potential energy curve for the (1)${}^1{\Pi }_u$ state is proposed, but the (1)${}^1{\Pi }_u$ state is only characterized by its coupling to the A state, and no direct transition to a level of the (1)${}^1{\Pi }_u$ could be uniquely identified due to the overlapping spectral structures.

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Cited by in corpus (3)

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