Rostock 2019 – wissenschaftliches Programm
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MO: Fachverband Molekülphysik
MO 12: High Resolution Spectroscopy and Precision Experiments
MO 12.3: Vortrag
Mittwoch, 13. März 2019, 11:00–11:15, S HS 002 Biologie
Predicting para-ortho conversion in ammonia — •Guang Yang1,4, Vinicius Silva de Oliveira2,4, Christoph Heyl2, Andrey Yachmenev1,3, Ingmar Hartl2, and Jochen Küpper1,3,4 — 1Center for Free-Electron Laser Science, DESY, Notkestrasse 85, Hamburg — 2DESY, Notkestrasse 85, Hamburg — 3The Hamburg Center for Ultrafast Imaging, Luruper Chaussee 149, Hamburg — 4Department of Physics, University of Hamburg, Luruper Chaussee 149, Hamburg
We present a combined theoretical and experimental study of the hyperfine-resolved spectrum of ammonia and its deuterated isotopologues. The calculations have been performed using the variational approach TROVE, a new spectroscopically determined potential energy surface, and ab initio quadrupole, spin-spin, and spin-rotation coupling surfaces. The computed spectroscopic line lists cover transitions between levels with rotational excitations up to J=20 and vibrational band centers with up to 8000 cm−1 above the zero-point-energy level.
For the spectroscopic observation of the para-ortho interconversion we use mid-infrared frequency comb spectroscopy in both ammonia vapour and a cold molecular beam. Furthermore, its modulation by external electric field is discussed. Our theoretical model, i.e., the underlying potential energy surface will be refined using the experimentally observed transitions.