| Fourier transform ion cyclotron mass spectrometry (FT-ICR MS) has received considerable attention for its ability to make mass measurements with a combination of resolution and accuracy that is higher than any other mass spectrometer. It can be used to obtain high-resolution mass spectra from ions generated by practically every known ionization method, to perform tandem mass spectrometric measurements, and to examine ion chemistry and photochemistry. Its versatility follows from the fact that it is an ion trapping instrument. The instrument mass analyzes and detects ions using methods which are unique among mass spectrometers.; FT-ICR MS was used to measure the binding energies of cyclodextrin:amino acid complexes in the gas-phase. Cyclodextrins are cyclic oligosaccharides that form truncated, cone-shaped molecules. The most common are referred to as α-, β-, and γ-cyclodextrin which contain 6, 7, and 8 glucose units in the ring, respectively. The cavity that is formed by these molecules is hydrophobic, which lends to their ability as a “host” molecule for the study of host-guest chemistry. Collision-induced dissociation was used to measure the binding energies between the cyclodextrin host molecules and amino acid guest ions.; FT-ICR MS was also used to study the photodissociation of polycyclic aromatic hydrocarbon cations that are of interstellar importance. It has become a widely accepted notion that PAH cations are the carriers of the diffuse interstellar bands that have been measured for years by astronomers. The unknown link is to find exactly what PAH cations are responsible for the bands. Experiments have been performed to answer this question. Two major themes are repeated for the fluorene, acenaphthylene, diphenylacetylene, and naphthalene cations: monitoring the generation of new ions formed as a function of trapping time in the analyzer cell, and analyzing the products that are generated after irradiation from a xenon arc lamp. Results from the first series of experiments reveal that new ions are being formed which result from ion-molecule reactions between neutral parents and parent ions. The second set of experiments show that the ions generated from the ion-molecule reactions are fragmenting into smaller ions as a result of the irradiation from the xenon arc lamp. |
