Optical Properties of Isolated Molecules and Clusters
Trapped ion Laser Induced Fluorescence (TLIF) is an experiment for luminescence spectroscopy of
isolated trapped ions in the gas phase. It combines the advantages of mass
spectrometric analysis with laser induced luminescence characterization of the
species studied. Ions are electro-sprayed using a nano electrospray ionization
source (nano-ESI), trapped, mass selected and thermalized down to liquid
nitrogen temperature in the center of a Paul trap. Trapped ions are excited by continuous wave lasers (argon ion-, diode- or dye-laser) crossing the ion cloud.
Luminescence collected by an inverted microscope is either integrated using a
photomultiplier or dispersed using a spectrograph coupled to a CCD
camera.
TLIF allows determination of intrinsic
properties of organic and inorganic emitters. It provides information on
energy levels of the emitting states, on the time constants of radiative
and non-radiative processes (currently over the 10-6 to
102 s range), as well as on the influence of solvent interactions on
the processes involved. TLIF offers unique capabilities such as the study
of different charge and aggegation states as well as stoichiometries not available in condensed phase. It also
allows performing reactivity studies between excited states and gas-phase
species such as oxygen.
Vibronic coupling of the ligand-centered phosphorescence of gas-phase lanthanide complexes

Correlation of structure, gas-phase photoluminescence and ion-mobility spectroscopy with DFT and ligand-field theory

Nonanuclear Eu- and Gd-complexes
We report the intrinsic luminescence properties of nonanuclear europium(III) and gadolinium(III) 9-hydroxyphenalen-1-one (HPLN)−hydroxo complexes. Luminescence spectra of [Eu9(PLN)16(OH)10]+ ions reveal an europium-centered emission dominated by a 4-fold split Eu(III) hypersensitive transition. The corresponding Gd(III) complex shows a broad emission from a ligand based triplet state with an onset of about 1000 wavenumbers in excess of the europium emission. As supported by photoluminescence lifetime measurements for both complexes, we deduce an efficient europium sensitization via PLN-based triplet states. The luminescence spectra of the complexes are discussed in terms of a square antiprismatic europium/gadolinium core structure as suggested by density functional computations. J. Phys. Chem. Lett, 2014, 5, 1727 and Inorganic Chemistry, 2016, 55, 3316
Intrinsic fluorescence properties of rhodamine cations
The gas phase triplet state lifetimes and dispersed fluorescence spectra of several types of rhodamine cations thermalized at 85 K have been investigated. The measured triplet lifetimes of rhodamine cations Rh6G+, Rh575+, RhB+, and Rh101+ are the order of seconds, several orders of magnitude longer than those typically observed for the same dyes in optical condensed phase measurements. Dispersed fluorescence emission spectra in the gas phase at 85 K have been measured and compared to density functional calculations.
More see JPC A, 2010, 114, 5509-5514 and PCCP 2013, 15, 8162-8170
Europium complexes
Gas phase dispersed photoluminescence spectra of europium (III)
9-hydroxylphenalen-1-one (HPLN) complexes cationized by alkali metals,
[Eu(PLN)3M]+ with M=Li, Na, K, Rb, and Cs, have been studied. The mass selected
alkali cation adducts display a split hypersensitive Eu3+ emission band. One of
the two emission components shows a linear dependence on the radius of the
alkali cation whereas the other component displays a quadratic dependence
thereon. In addition, the relative intensities of both components invert in the
same order. The experimental results are interpreted with the support of density
functional calculations and Judd-Ofelt theory, yielding also structural
information on the isolated [Eu(PLN)3M]+ chromophores. More see JPC A, 2013
TLIF publications
- Vibronic Coupling Analysis of the Ligand-Centered Phosphorescence of Gas-Phase Gd(III) and Lu(III) 9-Oxophenalen-1-one Complexes
J. Chmela, J.-F. Greisch, M. E. Harding, W. Klopper, M. M. Kappes and D. Schooss
Journal of Physical Chemistry A, 2018, 122, 2461 - Correlation of the structural information obtained for europium-chelate ensembles from gas-phase photoluminescence and ion-mobility spectroscopy with density-functional computations and ligand-field theory
J. F. Greisch, J. Chmela, M. E. Harding, D. Wunderlich, B. Schafer, M. Ruben, W. Klopper, D. Schooss and M. M. Kappes
Physical Chemistry Chemical Physics, 2017, 19, 6105 - Gas-Phase Photoluminescence Characterization of Stoichiometrically Pure Nonanuclear Lanthanoid Hydroxo Complexes Comprising Europium or Gadolinium
J. F. Greisch, J. Chmela, M. E. Harding, W. Klopper, M. M. Kappes and D. Schooss
Inorganic Chemistry, 2016, 55, 3316 - Photoluminescence Spectroscopy of Mass-Selected Electrosprayed Ions Embedded in Cryogenic Rare-Gas Matrixes
B. Kern, J.F. Greisch, D. Strelnikov, P. Weis, A. Bottcher, M. Ruben, B. Schafer, D. Schooss and M.M. Kappes
Analytical Chemistry, 2015, 87, 11901 - Characterization of Nonanuclear Europium and Gadolinium Complexes by Gas-Phase Luminescence Spectroscopy
J.-F. Greisch, M. E. Harding, B. Schäfer, M. Ruben, W. Klopper, M. M. Kappes and D. Schooss
Journal of Physical Chemistry Letters, 2014, 5, 1717 - Substitutional Photoluminescence Modulation in Adducts of a Europium Chelate with a Range of Alkali Metal Cations: A Gas-Phase Study
J.-F. Greisch, M. E. Harding, B. Schäfer, M. Rotter, M. Ruben, W. Klopper, M. M. Kappes and D. Schooss
Journal of Physical Chemistry A, 2013 - Intrinsic fluorescence properties of rhodamine cations in gas-phase: triplet lifetimes and dispersed fluorescence spectra
J. F. Greisch, M. E. Harding, M. Kordel, W. Klopper, M. M. Kappes and D. Schooss
Physical Chemistry Chemical Physics, 2013, 15, 8162-8170 - Laser-Induced Fluorescence of Rhodamine 6G Cations in the Gas Phase: A Lower Bound to the Lifetime of the First Triplet State
M. Kordel, D. Schooss, C. Neiss, L. Walter and M. M. Kappes
Journal of Physical Chemistry A, 2010, 114, 5509-5514