Protonation isomers of gas-phase nicotineH+ are separated and assigned using a combination of FAIMS and UV photodissociation action spectroscopy.

Ion-trap mass spectrometry maps the discrete steps in the reaction of I− and Br− with gaseous ozone.

The influence of oriented electric fields on chemical reactivity and photochemistry is an area of increasing interest. Within a molecule, different protonation sites offer the opportunity to control the location of charge and thus orientation of electric fields. New techniques are thus needed to discriminate between protonation isomers in order to understand this effect. This investigation reports the UV-photodissociation action spectroscopy of two protonation isomers (protomers) of 1,3-diazanaphthalene (quinazoline) arising from protonation of a nitrogen at either the 1- or 3-position. It is shown that these protomers are separable by field-asymmetric ion mobility spectrometry (FAIMS) with confirmation provided by UV-photodissociation (PD) action spectroscopy. Vibronic features in the UVPD action spectra and computational input allow assignment of the origin transitions to the S1 and S5 states of both protomers. These experiments also provide vital benchmarks for protomer-specific calculations and examination of isomer-resolved reaction kinetics and thermodynamics.

The low-lying electronic states of Irgacure 2959, a Norrish-type I photoinitiator, complexed with a single metal cation are investigated in the gas-phase by photodissociation action spectroscopy. Analysis of the band-shifts using quantum chemical calculations (TD-DFT and SCS-CC2) reveals the underlying influence of the charge on the key electronic energy levels. Since the

Ultraviolet-photodissociation (UVPD) mass spectrometry is an emerging analytical tool for structural elucidation of biomolecules including lipids. Gas phase UVPD of ionised fatty acids (FAs) can promote fragmentation that is diagnostic...