Molecules in Electromagnetic Fields by Krems Roman V

Author:Krems, Roman V.
Language: eng
Format: epub
ISBN: 9781119387398
Publisher: John Wiley & Sons, Inc.
Published: 2018-04-27T20:13:29+00:00

Figure 6.10 Time evolution of the CaH spectrum in a magnetic trap. These spectra reveal that CaH molecules in the high‐field‐seeking state (negative frequency shifts) quickly leave the trap. The trapped molecules in the low‐field‐seeking state (positive frequency shifts) are confined and compressed toward the center of the trap.

Source: Reproduced with permission from Weinstein et al. 1998 [227]. © 1998, Nature Publishing Group.

The importance of the experiment of Weinstein et al. is hard to overestimate. Beyond stimulating the research of cold molecules, magnetic trapping of molecules in the environment of an inert buffer gas became a useful tool for the Zeeman spectroscopy [235, 236], accurate measurement of the radiative lifetimes of long‐lived molecular levels [212], and the study of atomic and molecular collisions at temperatures near and below 1 K. In addition to CaH, the experiments demonstrated the trapping of CrH and MnH [237] as well as NH [238, 239] radicals. Long lifetimes of magnetically trapped molecules exceeding 20 s have been achieved by subsequent authors [239]. Vanhaecke et al. [240] trapped Cs2 molecules in an exited, metastable state in a quadrupole magnetic trap, holding the molecules for about one second. Hogan et al. [241] demonstrated the loading of magnetic atoms in a trap after Zeeman deceleration, a technique that can be likewise used for molecules. Riedel et al. [242] demonstrated that multiple packets of molecules from a pulsed molecular beam can be loaded in the same magnetic trap, thus resulting in accumulation of molecules and increased phase space density. In this experiment, the NH molecules were decelerated while in an electronically excited state. Once the molecules reached the center of the magnetic trap, they were optically pumped to another electronically excited state, which decays spontaneously to the ground state.

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