2381/542 Klaus von Haeften Klaus von Haeften A. Metzelthin A. Metzelthin S. Rudolph S. Rudolph V. Staemmler V. Staemmler M. Havenith M. Havenith High Resolution Spectroscopy of NO in Helium Droplets: A Prototype for Open Shell Molecular Interactions in a Quantum Solvent. University of Leicester 2007 IR content 2007-08-02 10:14:22 Journal contribution https://figshare.le.ac.uk/articles/journal_contribution/High_Resolution_Spectroscopy_of_NO_in_Helium_Droplets_A_Prototype_for_Open_Shell_Molecular_Interactions_in_a_Quantum_Solvent_/10077329 We have measured the high-resolution infrared spectrum of the radical NO in the 2Π1/2 state in superfluid helium nanodroplets. The features are attributed to the Λ doubling splitting and the hyperfine structure. The hyperfine interaction is found to be unaffected by the He solvation. For the Λ-doubling splitting, we find a considerable increase by 55% compared to the gas phase. This is explained by a confinement of the electronically excited NO states by the surrounding He. The rotational level spacing is decreased to 76% of the gas phase value. The IR transition to the J = 1:5 state is found to be homogeneously broadened. We attribute both observations to the coupling between the molecular rotation and phonon/roton excitations in superfluid 4He droplets.