Hannover 2020 – wissenschaftliches Programm
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MO 4.2: Vortrag
Montag, 9. März 2020, 14:30–14:45, f142
Threshold Photoelectron Spectroscopy of IO and HOI — •Domenik Schleier1, Engelbert Reusch1, Lisa Lummel1, Patrick Hemberger2, and Ingo Fischer1 — 1Institute for physical and theoretical Chemistry, Würzburg, Germany — 2Paul-Scherrer-Institute (PSI), Villigen, Switzerland
IO and HOI represent key intermediates and precursors in the formation iodine oxide particles (IOPs). During their formation they catalytically destroy ozone and ultimately influence cloud lifetimes, contributing negatively to earths radiative balance. Both molecules have been characterized using multiple spectroscopic techniques like UV/Vis, IR, EPR, microwave spectroscopy and photoelectron detachment. However, information on the cations and thermodynamic data is still scarce. We therefore employ PEPICO (Photoelectron Photoion Coincidence) spectroscopy to record mass-selected threshold photoelectron spectra (ms-TPES). The CRF-PEPICO (Combustion Reactions Followed by PEPICO) setup at the vacuum ultraviolet (VUV) beamline of the Swiss Light Source (SLS) uses a slow-flow reactor in which IO and HOI were produced from photolyzing an I2/O3 mixture at 532 nm. The ionization energies were determined to be 9.71 +- 0.02 eV and 9.79 +- 0.02 eV for IO and HOI, respectively. While HOI+ shows a vibrational frequency of 660 cm-1, IO+ exhibits a spin-spin splitting resulting in the separation the 3Σ- ground states. This splitting results in two different determined vibrational frequencies for the cation of 810 cm-1 and 730 cm-1.