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Universität zu Köln
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Mathematisch-Naturwissenschaftliche Fakultät
Fachgruppe Physik

I. Physikalisches Institut

FREQUENCY COMB

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The mid-infrared spectrometer consists of a high power optical parametric oscillator (Aculight Argos) and a frequency
comb (Menlo Systems), and can be coupled to our 22-pole ion traps. The idler frequency at 3 μm is measured acurately by analyzing the pump and signal beat frequencies with the comb. This is done via two spec-
trum analyzers, allowing for a wide and continuous scanning ideal for spectroscopy of cold molecules
with unknown spectra. The potential of this approach has been tested by measuring ro-vibrational
lines of CH5+ in a 22-pole ion trap via action spectroscopy of only several thousand cold ions. The
current setup limits the precision of the line center frequency determination to some 100 kHz with
ample room for future improvements. Following this approach, ground state combination differences
of molecular ions can be predicted in order to identify them in astronomical objects.

 

Frequency comb assisted mid-infrared spectroscopy of cold molecular ions
O. Asvany, J. Krieg, and S. Schlemmer
Rev. Sci. Instrum. 83, Art. No. 093110 (2012)