The ¹B₂ ← ¹A₁ Electronic Transition of Selenium Dioxide

Abstract

<p>The B ← X system of selenium dioxide was studied in absorption in the gas phase and has been assigned to the electronic transition ¹B₂ ← X, ¹A₁. A complete vibrational analysis of the electronic transition is presented. The geometry of the excited state has been determined completely from rotational analysis of the l₀³ vibronic band and further confirmed by Frank-Condon calculations. The previously unknown ground state fundamentals ν₁ and ν₂ have been determined along with the three fundamentals of the ¹B₂ excited state. It is proposed that selenium dioxide has an asymmetric structure with unequal bond lengths in certain vibronic levels of the excited state involving ν₃ as a result of a double-minimum potential along the Q₃ co-ordinate.</p>