Heidelberg 2015 – scientific programme
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MO: Fachverband Molekülphysik
MO 17: Cold Molecules 3
MO 17.5: Talk
Thursday, March 26, 2015, 12:15–12:30, PH/HS1
Obeservation of molecular dimers in IR absorption Spectra of liquid hydrogen isotopologues — •Robin Groessle and Sebastian Mirz — Karlsruhe Institute of Technology (KIT), Institute of Technical Physics (ITEP), Tritium Laboratory Karlsruhe (TLK)
One of the main tasks of the Tritium Laboratory Karlsruhe (TLK) is the development of analytical methods for hydrogen isotopologues. A promising method for liquid hydrogen is IR absorption spectroscopy. For this a cryogenic sample cell, able to liquefy the hydrogen isotopologues, with an open beam path for IR light, has been developed and set up.
This talk will focus on the contribution of hydrogen dimers in the liquid phase to the IR spectra. The dimer model predicts non linear effects in the IR spectra. Thus the comparison of several spectra from different samples, including hydrogen, deuterium and mixtures enables a clear identification of dimers. In the case of pure H2 a bunch of lines in between 8000 cm−1 to 8800 cm−1 and for D2 between 5900 cm−1 to 6500 cm−1, both corresponding to the 2nd vibrational branch of homomolecular dimers, are observed. A third spectrum of mixed H2 and D2 then shows in addition several lines in between, corresponding to hetreomolecular dimers. In addition these measurements have been repeated with variing compositions. And so the concentration dependence of the absorption intensity can be shown to follow predictions from this dimer model.