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 Title: FIRST INFRARED PREDISSOCIATION SPECTRA OF He-TAGGED PROTONATED PRIMARY ALCOHOLS AT 4 K Author(s): Schlemmer, Stephan Contributor(s): Thorwirth, Sven; Jusko, Pavol; Brünken, Sandra; Asvany, Oskar; Oomens, J.; Redlich, Britta; Stoffels, Alexander Subject(s): Mini-symposium: Accelerator-Based Spectroscopy Abstract: Cryogenic multipole ion traps have become popular devices in the development of sensitive action-spectroscopic techniques. The low ion temperature leads to enhanced spectral resolution, and less congested spectra. In the early 2000s, a 22-pole ion trap was coupled to the Free-Electron Laser for Infrared eXperiments (FELIX), yielding infrared Laser Induced Reaction (LIR) spectra of the molecular ions chem{C_2H_2}textsuperscript{+} and chem{CH_5}textsuperscript{+}footnote{Asvany et al.: Phys. Rev.Lett. 94, 073001 (2005), Asvany et al.: Science 309, 1219-1222 (2005)}. This pioneering work showed the great opportunities combining cold mass-selected molecular ions with widely tunable broadband IR radiation. In the past year a cryogenic (T$>$3.9 K) 22-pole ion trap designed and built in Cologne (FELion) has been successfully coupled to FELIX, which in its current configuration provides continuously tunable infrared radiation from 3 $mu$m to 150 $mu$m, hence allowing to probe characteristic vibrational spectra in the so-called �fingerprint region� with a sufficient spectral energy density also allowing for multiple photon processes (IR-MPD). Here we present the first infrared predissociation spectra of He-tagged protonated methanol and ethanol (chem{MeOH_2}textsuperscript{+}/chem{EtOH_2}textsuperscript{+}) stored at 4 K. These vibrational spectra were recorded with both a commercial OPO and FELIX, covering a total spectral range from 3700 wn to 550 wn at a spectral resolution of a few wn. The H-O-H stretching and bending modes clearly distinguish the protonated alcohols from their neutral analoga. For chem{EtOH_2}textsuperscript{+}, also IR-MPD spectra of the bare ion could be recorded. The symmetric and antisymmetric H-O-H stretching bands at around 3 $mu$m show no significant shift within the given spectral resolution in comparison to those recorded with He predissociation, indicating a rather small perturbation caused by the attached He. The vibrational bands were assigned using quantum-chemical calculations on different levels of theory. The computed frequencies correspond favorably to the experimental spectra. Subsequent high resolution measurements could lead to a better structural characterization of these protonated alcohols. Issue Date: 25-Jun-15 Publisher: International Symposium on Molecular Spectroscopy Citation Info: ACS Genre: CONFERENCE PAPER/PRESENTATION Type: Text Language: English URI: http://hdl.handle.net/2142/79191 Date Available in IDEALS: 2016-01-05
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