Year: 2026
Type: article
Abstract: High Resolution Image Download MS PowerPoint Slide Rotationally resolved electronic spectra have been recorded for gas-phase UO 2 . Analysis of the rotational fine structure confirms that the ground state is X 3 Φ 2u, derived from the O 2– U 4+ (5f7s)O 2– electronic configuration. All transitions observed below 14500 cm –1 were assigned to the [11.51]3 g ↔ X 3 Φ 2u transition, which correlates with the metal-centered 5f7p ↔ 5f7s electron promotion. The symmetric stretch and bending vibrational modes were active in the spectrum. Ground-state vibrational fundamentals of 853(5) and 133(5) cm –1 were determined along with a vibrationally averaged bond length of 1.781 Å. Spectra for the [17.68]4 g ↔ X 3 Φ 3u transition exhibited the same lower state vibrational frequencies, confirming that the X 3 Φ 3u state also arises from the 5f7s configuration. Fluorescence decay lifetimes for the excited states were in the range of 1.5–4.7 μs, values that were anomalously long for electric dipole-allowed transitions. The long lifetimes are attributed to extensive mixing with a dense background of vibronic dark states.
Authors: Jiande Han, Jiayue Lin, Michael C. Heaven
Institution: Emory University
Language: English
Subfield: Spectroscopy
Field: Chemistry
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $4,500
Funder: Basic Energy Sciences
Award: G2003723584
OpenAlex ID: W7130821993