Core excitation in O3 localized to one of two symmetry-equivalent chemical bonds: Molecular alignment through vibronic coupling

Abstract

Core excitation from terminal oxygen OT in O3 is shown to be an excitation from a localized core orbital to a localized valence orbital. The valence orbital is localized to one of the two equivalent chemical bonds. We experimentally demonstrate this with the Auger Doppler effect which is observable when O3 is core-excited to the highly dissociative OT 1s −1 7a 1 1 state. Auger electrons emitted from the atomic oxygen fragment carry information about the molecular orientation relative to the electromagnetic field vector at the moment of excitation. The data together with analytical functions for the electron-peak profiles give clear evidence that the preferred molecular orientation for excitation only depends on the orientation of one bond, not on the total molecular orientation. The localization of the valence orbital "7a1" is caused by mixing of the valence orbital "5b2" through vibronic coupling of anti-symmetric stretching mode with b2-symmetry. To the best of our knowledge, it is the first discussion of the localization of a core excitation of O3. This result explains the success of the widely used assumption of localized core excitation in adsorbates and large molecules.

Disentangling the resonant Auger spectra of ozone: overlapping core-hole states and core-excited state dynamics

“…1,2 Besides its fundamental relevance in Earth's atmosphere, ozone has also vast industrial and medicinal applications. [3][4][5][6] Due to its relevance, the electronic spectroscopy of ozone has been extensively studied both at the valence [7][8][9][10][11] and core-excited [12][13][14][15][16][17][18][19] regions. Deep ultraviolet photodissociation of ozone following an excitation from the ground electronic state to the excited B( 1 B 2 ) state [Hartley state], according to…”

“…1,2 Besides its fundamental relevance in Earth's atmosphere, ozone has also vast industrial and medicinal applications. 3–6 Due to its relevance, the electronic spectroscopy of ozone has been extensively studied both at the valence 7–11 and core-excited 12–19 regions. Deep ultraviolet photodissociation of ozone following an excitation from the ground electronic state to the excited B( 1 B 2 ) state [Hartley state], according tois responsible for the protective function of the ozone layer in the stratosphere, although the fourth ionized state of O 3 + was also found to lead to photofragmentation of O 3 + → O 2 + O + by visible light.…”