Heidelberg 2015 – scientific programme

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MO: Fachverband Molekülphysik

MO 4: Cold Molecules 1

MO 4.2: Talk

Monday, March 23, 2015, 14:45–15:00, PH/SR106

Internal state thermometry of buffer-gas cooled and electrically guided polar 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 general technique for detecting the internal states of polyatomic molecules after cryogenic buffer-gas cooling [1] and electrostatic guiding [2]. Bright beams of polar molecules produced by a cryogenic buffer-gas cell are extracted by electric quadrupole guiding, and delivered to a region of homogeneous offset electric field, where different Stark sub-levels are split. Applying an RF field resonant with a particular splitting drives Δ M=±1 transitions for the selected rotational state. Only molecules remaining in low-field-seeking states are further guided to a quadrupole mass spectrometer for detection. The population in each rotational state can be derived from this depletion signal. After taking into account the velocity distribution in the guide and the Stark shift of each state, internal temperatures can be assigned to the guided molecular beams. This method is extremely simple to implement and compatible with the existing electric guiding technique. Application to a variety of molecular species as well as for a range of parameters for the buffer-gas source is shown.

[1] L.D. van Buuren et al., Phys. Rev. Lett. 102, 033001 (2009)

[2] S.A. Rangwala et al., Phys. Rev. A 67, 043406 (2003)