The FELion cryogenic ion trap beam line at the FELIX free-electron laser laboratory: infrared signatures of primary alcohol cations

Abstract

The FELion beamline – a cryogenic 22-pole trap for vibrational spectroscopy of molecular ions at the FELIX Laboratory.

Infrared action spectroscopy of doubly charged PAHs and their contribution to the aromatic infrared bands

“…The vibrational spectra of PAH dications were recorded using the FELion cryogenic 22-pole ion trap setup coupled to the free-electron laser FEL-2 at the FELIX Laboratory (Oepts et al 1995). The FELion experimental setup has already been described in detail in Jusko et al (2019). To provide a brief overview, the respective vapors of PAHs are ionized by electron impact ionization (EI), which results in the formation of several charged fragments including the doubly charged naphthalene cation (C 10 H 8 2+ , mass-to-charge ratio of m/z=64, naph 2+ in the following) and the doubly charged phenanthrene and anthracene cations (C 14 H 10 2+ , m/z=89, phen 2+ , and anth 2+ , resp.).…”

“…Earlier IRPD studies applied to PAH ions used a molecular beam cooled by supersonic expansion, and they provided gas phase spectra of cold protonated (Ricks et al 2009) and cationic (Piest et al 1999) naphthalene and phenanthrene (Piest et al 2001) via dissociation of their weakly bound complexes with Ar. With the advent of cryogenic ion trapping techniques, IRPD spectra can now be recorded at temperatures as low as 4 K, allowing for the use of weaker bound rare-gas atoms such as He or Ne as tagging agents, introducing smaller shifts of vibrational bands in the experimental spectra (Asmis et al 2002;Jašík et al 2014;Günther et al 2017;Gerlich et al 2018;Jusko et al 2019). The advantage of IRPD compared to multiphoton IRMPD spectroscopy is that dissociation happens after absorption of a single photon, with approximately constant efficiency, resulting in experimental vibrational spectra more closely resembling the linear absorption spectrum of the ions, both in intensity and band positions.…”

Gas-Phase Vibrational Spectroscopy of the Hydrocarbon Cations l-C3H+, HC3H+, and c-C3H2+: Structures, Isomers, and the Influence of Ne-Tagging

“…The combination of a cryogenic ion trap instrument with the widely tunable free electron lasers at the FELIXa Laboratory 34 enabled us now to measure the vibrational spectra of C 3 H + and C 3 H 2 + for the first time. Broadband IR spectra covering most of the fundamental bands were recorded using infrared-predissociation (IR-PD) action spectroscopy of the isolated ions tagged with a Ne atom.…”

Rotational action spectroscopy of trapped molecular ions

“…Because of this distance a careful and tedious adjustment of the THz-setup on an optical test bench was mandatory. The experience with these first rotational measurements lead finally to the novel ion trap machine designs developed in Cologne 42,52 . Also, a hydrogen sample highly enriched in p-H 2 , produced in an external catalytic p-H 2 -generator, has been used in the experiment.…”

“…Typically, such a setup consists of an ion source, a first mass filter (which could be a quadrupole or a time-of-flight mass analyzer), the ion trap, followed again by a second mass filter and finally the ion detector. Several such cryogenic trap machines have been described in the literature in detail 35,42,[46][47][48][49][50][51][52][53] , as well as the central part, typically a multipolar cryogenic ion trap [54][55][56] . The experiments are conducted in a pulsed mode.…”