The 4190 Å Absorptipn System of Selenium Dioxide

Abstract

<p>The 4190 Å absorption (C-) system of selenium dioxide has been studied in the gas phase and has been assigned to the ³B₂ ← X ¹A₁ electronic transition. The three ground state and the three excited state fundamental frequencies for Se⁷⁸O₂¹⁶, Se⁷⁸O₂¹⁸ and Se⁸⁰O₂¹⁶ isotopes are determined from the vibrational analysis. The intensity of the singlet-triplet transition is borrowed via the spin-orbit and the spin-vibronic coupling mechanism. The geometry of selenium dioxide in the excited state has been determined from the rotational analysis of the 2³₀3⁰₁ vibronic band. The intensities of the rotational transitions for this band are borrowed from singlet-singlet transitions between the ¹A₁ ground state and the ¹B₁ and ¹B₂ excited states. Coupling of the electronic and the orbital angular moments in the ³B₂ excited state is closely approximated by that in the Case (b) coupling limit.</p>