Gas-phase electronic spectra of HCH ( = 2-6) chains.

Highly unsaturated carbon chains are generated in combustion processes and electrical discharges, and are confirmed constituents of the interstellar medium. In hydrogen-rich environments smaller carbon clusters tend to exist as linear chains, capped on each end by hydrogen atoms. Although the HCH polyacetylene chains have been extensively characterized spectroscopically, the corresponding odd HCH chains have received far less attention.

Bond dissociation energies for Fe2+, Fe2O+, and Fe2O2+ clusters determined through threshold photodissociation in a cryogenic ion trap.

Understanding and controlling the chemical behavior of iron and iron oxide clusters requires accurate thermochemical data, which, because of the complex electronic structure of transition metal clusters, can be difficult to calculate reliably. Here, dissociation energies for Fe2+, Fe2O+, and Fe2O2+ are measured using resonance enhanced photodissociation of clusters contained in a cryogenically cooled ion trap. The photodissociation action spectrum of each species exhibits an abrupt onset for the production of Fe+ photofragments from which bond dissociation energies are deduced for Fe2+ (2.

Probing Colossal Carbon Rings.

Carbon aggregates containing between 10 and 30 atoms preferentially arrange themselves as planar rings. To learn more about this exotic allotrope of carbon, electronic spectra are measured for even cyclo[]carbon radical cations (-) using two-color photodissociation action spectroscopy. To eliminate spectral contributions from other isomers, the target cyclo[]carbon radical cations are isomer-selected using a drift tube ion mobility spectrometer prior to spectroscopic interrogation.

Disentangling Electronic Spectra of Linear and Cyclic Hydrogenated Carbon Cluster Cations, CH ( = 3-10).

Electronic spectra are measured for protonated carbon clusters (CH) containing between 7 and 21 carbon atoms. Linear and cyclic CH isomers are separated and selected using a drift tube ion mobility stage before being mass selected and introduced into a cryogenically cooled ion trap. Spectra are measured using a two-color resonance-enhanced photodissociation strategy, monitoring C photofragments (H atom loss channel) as a function of excitation wavelength.

An ion mobility mass spectrometer coupled with a cryogenic ion trap for recording electronic spectra of charged, isomer-selected clusters.

Infrared and electronic spectra are indispensable for understanding the structural and energetic properties of charged molecules and clusters in the gas phase. However, the presence of isomers can potentially complicate the interpretation of spectra, even if the target molecules or clusters are mass-selected beforehand. Here, we describe an instrument for spectroscopically characterizing charged molecular clusters that have been selected according to both their isomeric form and their mass-to-charge ratio.

Electronic spectra of positively charged carbon clusters-C (n = 6-14).

Electronic spectra are measured for mass-selected C (n = 6-14) clusters over the visible and near-infrared spectral range through resonance enhanced photodissociation of clusters tagged with N molecules in a cryogenic ion trap. The carbon cluster cations are generated through laser ablation of a graphite disk and can be selected according to their collision cross section with He buffer gas and their mass prior to being trapped and spectroscopically probed. The data suggest that the C (n = 6-14) clusters have monocyclic structures with bicyclic structures becoming more prevalent for C and larger clusters.