Themed collection Optical spectroscopy coupled with mass spectrometry methods

This themed issue reports on recent progress in the fast developing field of spectroscopy of ions by means of mass spectrometry coupled with optical spectroscopy. It focuses on both the experimental and theoretical aspects of this topic.

Molecular ions drifting through buffer gas are exposed to tunable laser light causing a detectable change in their collision cross section and arrival time at the ion detector. The effect can be exploited to obtain action electronic spectra for selected molecular isomers in the gas phase.

Anharmonic behavior of sulfated glucosamine resolved by hybrid GVPT2 approach.

Vibrational spectroscopy of size selected clusters reveals the extent to which interactions with Fe₂⁺ weaken proximate C–H bonds in methane ligands.

Gas-phase reduction of a Zn(II) complex followed by IR spectroscopy shows that the incoming electron is localized on the metal rather than on the ligand.

The first observation and characterization of the [heme Fe^III–O₂]⁺ complex. Determination of the Fe^III–O₂ binding energy.

Met–Trp oxidized products formed by γ radiolysis and their vibrational signatures.

IRMPD spectroscopy and theoretical studies reveal that a diverse mixture of minor 2,4-dihydroxy and O4 protonated tautomeric conformations of the protonated forms of uridine and 2′-deoxyuridine are populated by ESI.

The Driven Molecular Dynamics approach has been adapted and associated with the AMOEBA polarizable force field to assign and visualize vibrational modes in infrared spectra obtained by molecular dynamics simulations.

Photoexcitation of a T-shaped benzene dimer provides a sandwiched excimer in 10 ps accompanying a 1000 times faster intracluster vibrational energy redistribution rate than that of the benzene monomer.

Nonlinear effects in infrared action spectroscopy are experimentally quantified and successfully modeled for different inorganic clusters.

The sulfate ion is found to lie at the cluster surface in both cases.

We report infrared multiple photon dissociation spectra of cryogenically-cooled H₂PO₄⁻(H₂O)_n anions (n = 2–12) in the spectral range of the stretching and bending modes of the solute anion (600–1800 cm⁻¹).

Crown ethers show a dramatic effect on the electronic spectra and fragmentation patterns of guest species.

Action spectroscopy and first principles calculations are performed to characterize the optical properties of prodigiosin, and its sensibility to protonation, counter-ion binding, and isomerization.

Single water molecule hydration stabilizes two quasi-isoenergetic complexes of cytosine⋯Ag⁺.

The combination of conformation selective far-IR/UV double resonance spectroscopy with Born–Oppenheimer molecular dynamics (BOMD) simulations is presented here for the structural characterization of the Ac-Phe-Pro-NH₂ peptide in the far-infrared spectral domain, i.e. for radiation below 800 cm⁻¹.

Gas-phase two-photon UV action spectra of protonated quinoline and isoquinoline cations are reported revealing two broad, vibrationally-structured electronic bands and multiple photoproduct channels.

A moderate-resolution infrared multiple photon dissociation (IRMPD) spectrum of protonated bis(2-methoxyethyl) ether (diglyme) was obtained using a grating-tuned CO₂ laser.

The gas phase structures of (de)protonated O-sulfoserine ions have been revealed by infrared multiple photon dissociation (IRMPD) spectroscopy and computations.

Highly polarized water networks are found in the micro hydaration of protonated trimethylamine.

Excited state properties of cold protonated ions are revealed by a combination of laser spectroscopy and ab initio calculations.

Gas-phase IR spectroscopy, ion–molecule reactions, collision-induced dissociation and computational chemistry in combination form a powerful tool to gain insights into the structure of one-electron oxidised guanine in DNA and its resultant chemistry.

We explore conformational space of triply protonated bradykinin. Three conformational families are mobility-separated and spectroscopically characterized. Kinetically trapped structures are identified via annealing.

Distance-sensitive energy transfer and molecular dynamics are used to generate experimentally corroborated structures for peptides in the gas phase.

The conformational flexibility effect on the valence and core electronic structures of D-cycloserine.

The true colors of chlorophyll a and b, isolated in vacuo, are revealed from a combination of gas-phase ion spectroscopy and TD-DFT calculations.

Zinc and cadmium dications bind cysteine in tridentate structures at the amine and carbonyl groups and deprotonated sulfur atom.

The effects of ionisation and protonation on the geometric and electronic structure of a prototypical aromatic amino-alcohol with two chiral centres are revealed by IR and UV spectroscopy.

The VUV photoionisation and photofragmentation of a mass-selected, ligated silver deuteride nanocluster was studied.

The hydroxide frequency in MOH(H₂O)⁺ is a sensitive probe of charge transfer.

The electrostatic potential map of the neutral guanine tetrad showing the negative hole in the centre.

The combination of Laval expansions with single photon VUV ionization and linear time of flight mass spectrometry allows one to study weakly-bound molecular aggregates under equilibrium conditions.

Where does the proton go?

Calculations and IR spectra reveal the effects of anharmonicity and dispersion on the cation–π interaction in this prototypical neurotransmitter.

We investigate the solvent effects on photodissociation dynamics of the S–H bond in ethanethiol CH₃CH₂SH (EtSH).

Action spectroscopy of substance P, a model undecapeptide, has been probed from 5.2 eV to 20 eV.