Rotational coherence spectroscopy of molecules in helium nanodroplets: Reconciling the time and the frequency domains
arXiv:2006.02694 · doi:10.1103/PhysRevLett.125.013001
Abstract
Alignment of OCS, CS and I molecules embedded in helium nanodroplets is measured as a function of time following rotational excitation by a non-resonant, comparatively weak ps laser pulse. The distinct peaks in the power spectra, obtained by Fourier analysis, are used to determine the rotational, B, and centrifugal distortion, D, constants. For OCS, B and D match the values known from IR spectroscopy. For CS and I, they are the first experimental results reported. The alignment dynamics calculated from the gas-phase rotational Schrödinger equation, using the experimental in-droplet B and D values, agree in detail with the measurement for all three molecules. The rotational spectroscopy technique for molecules in helium droplets introduced here should apply to a range of molecules and complexes.
ASC and LC contributed equally. 7 pages, 3 figures