Cold Ion-Molecule Reactions in the Extreme Environment of a Coulomb Crystal

Coulomb crystals provide a unique environment in which to study ion-neutral gas-phase reactions. In these cold, trapped ensembles, we are able to study the kinetics and dynamics of small molecular systems. These measurements have connections to chemistry in the Interstellar Medium (ISM) and planetary atmospheres. This Feature Article will describe recent work in our laboratory that uses Coulomb crystals to study translationally cold, ion-neutral reactions. We provide a description of how the various affordances of our experimental system allow for detailed studies of the reaction mechanisms and the corresponding products. In particular, we will describe quantum-state resolved reactions, isomer-dependent reactions, and reactions with a rarely studied, astrophysically relevant ion, CCl+.

UV-vis spectroscopy of gas-phase ions

Photodissociation action spectroscopy has made a great progress in expanding investigations of gas-phase ion structures. This review deals with aspects of gas-phase ion electronic excitations that result in wavelength-dependent dissociation and light emission via fluorescence, chiefly covering the ultraviolet and visible regions of the spectrum. The principles are briefly outlined and a few examples of instrumentation are presented. The main thrust of the review is to collect and selectively present applications of UV-vis action spectroscopy to studies of stable gas-phase ion structures and combinations of spectroscopy with ion mobility, collision-induced dissociation, and ion-ion reactions leading to the generation of reactive intermediates and electronic energy transfer.

Laser Photodissocation, Action Spectroscopy and Mass Spectrometry Unite to Detect and Separate Isomers

The separation and detection of isomers remains a challenge for many areas of mass spectrometry. This article highlights laser photodissociation and ion mobility strategies that have been deployed to tackle...

Facile simultaneous synthesis of tetraaniline nanostructures/silver nanoparticles as heterogeneous catalyst for the efficient catalytic reduction of 4-nitrophenol to 4-aminophenol

Nanocomposites of tetraaniline (TAN) nanostructures/silver nanoparticles (Ag NPs) were synthesized by an interfacial polymerization method using N-phenyl-1, 4-phenylenediamine (NPPD), AgNO₃ and ammonium persulphate (APS) as monomer, oxidizing agent in immiscible solvent toluene–water respectively. The structure and morphology of the as-prepared TAN and Ag NPs were investigated by UV-visible spectroscopy, Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and thermogravimetry (TG). The results of FTIR spectroscopy confirmed the formation of TAN and Ag NPs and those of XRD showed the presence of the face centred cubic (fcc) phase of Ag NPs. The FESEM and TEM images gave direct evidence that Ag NPs stabilized with the TAN nanostructures. TGA indicated the enhanced thermal stability of the nanocomposites (NCs). The catalytic activity of TAN/Ag NCs was investigated for the model reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) in the presence of excess sodium borohydride.

Nanocomposites of tetraaniline/silver nanoparticles were synthesised using an interfacial polymerisation method. The catalytic activity was investigated for the model reduction of 4-nitrophenol to 4-aminophenol in the presence of excess sodium borohydride.

Intrinsic electronic spectra of cryogenically prepared protoporphyrin IX ions in vacuo – deprotonation-induced Stark shifts

We present electronic spectra containing the Q_x and Q_y absorption bands of singly and doubly deprotonated protoporphyrin IX, prepared as mass selected ions in vacuo at cryogenic temperatures, revealing vibronic structure of both bands.

Cryogenic Ion Spectroscopy of the Green Fluorescent Protein Chromophore in Vacuo

We present the spectrum of the S₁ ← S₀ transition of an anionic model for the chromophore of the green fluorescent protein in vacuo at cryogenic temperatures, showing previously unresolved vibrational features, and resolving the band origin at 20 930 cm^-1 (477.8 nm) with unprecedented accuracy. The vibrational spectrum establishes that the molecule is in the Z isomer at low temperature. At increased temperature, the S₁ ← S₀ band shifts to the red, which we tentatively attribute to emergent population of the E isomer.