Hannover 2016 – scientific programme
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MO: Fachverband Molekülphysik
MO 4: Cold Molecules & Helium Droplets 1
MO 4.4: Talk
Monday, February 29, 2016, 15:15–15:30, f142
Internal-state thermometry of cold polyatomic molecules — •Xing Wu, Thomas Gantner, Sotir Chervenkov, Martin Zeppenfeld, and Gerhard Rempe — Max-Planck-Institut für Quantenoptik, Hans-Kopfermann-Str. 1, D-85748 Garching, Germany
We present a new method for internal-state thermometry of guided polyatomic molecules. Bright beams of polar molecules are produced by a cryogenic buffer-gas cell and extracted by electrostatic guiding [1]. Their rotational-state distribution is probed via RF-resonant depletion spectroscopy. With the help of a complete trajectory simulation, resolving the guiding efficiency for all the thermally populated states, we are able to determine the internal temperature in the buffer-gas cell based on the RF depletion spectroscopy. This thermometry method is demonstrated for various regimes of buffer-gas cooling, beam formation, and for molecular species of different sizes, e.g., CH3F and CF3CCH. the results provide strong evidence that the collisional relaxation rate for rotational degrees of freedom is larger than for motional ones. In addition, the relaxation rates for states with different K-quantum number appear to be different.
[1] L.D. van Buuren et al., Phys. Rev. Lett. 102, 033001 (2009)