Mots-clés de l'auteur: cold ion spectroscopy ; UV spectroscopy ; high-resolution mass spectrometry ; photodissociation ; Orbitrap ; UV-MS ; gas phase ; biomolecular ions ; isomers ; conformers ; FRET ; phosphorylated peptides ; opioid peptides ; ephedrine ; gramicidin S ; homatropine ; leucine enkephalin.

Gas Phase Ion Chemistry, Volume 2 covers the advances in gas phase ion chemistry. The book discusses the stabilities of positive ions from equilibrium gas-phase basicity measurements; the experimental methods used to determine molecular electron affinities, specifically photoelectron spectroscopy, photodetachment spectroscopy, charge transfer, and collisional ionization; and the gas-phase acidity scale. The text also describes the basis of the technique of chemical ionization mass spectrometry; the energetics and mechanisms of unimolecular reactions of positive ions; and the photodissociation of gas-phase ions. The applications of molecular beam techniques to the study of ion-molecule collisions; as well as the variational treatment of charge transfer reactions are also encompassed. Chemists and biochemists will find the book invaluable.

The series Topics in Current Chemistry presents critical reviews of the present and future trends in modern chemical research. The scope of coverage is all areas of chemical science including the interfaces with related disciplines such as biology, medicine and materials science. The goal of each thematic volume is to give the non-specialist reader, whether in academia or industry, a comprehensive insight into an area where new research is emerging which is of interest to a larger scientific audience. Each review within the volume critically surveys one aspect of that topic and places it within the context of the volume as a whole. The most significant developments of the last 5 to 10 years are presented using selected examples to illustrate the principles discussed. The coverage is not intended to be an exhaustive summary of the field or include large quantities of data, but should rather be conceptual, concentrating on the methodological thinking that will allow the non-specialist reader to understand the information presented. Contributions also offer an outlook on potential future developments in the field. Review articles for the individual volumes are invited by the volume editors. Readership: research chemists at universities or in industry, graduate students.

The series Topics in Current Chemistry presents critical reviews of the present and future trends in modern chemical research. The scope of coverage is all areas of chemical science including the interfaces with related disciplines such as biology, medicine and materials science. The goal of each thematic volume is to give the non-specialist reader, whether in academia or industry, a comprehensive insight into an area where new research is emerging which is of interest to a larger scientific audience. Each review within the volume critically surveys one aspect of that topic and places it within the context of the volume as a whole. The most significant developments of the last 5 to 10 years are presented using selected examples to illustrate the principles discussed. The coverage is not intended to be an exhaustive summary of the field or include large quantities of data, but should rather be conceptual, concentrating on the methodological thinking that will allow the non-specialist reader to understand the information presented. Contributions also offer an outlook on potential future developments in the field. Review articles for the individual volumes are invited by the volume editors. Readership: research chemists at universities or in industry, graduate students.

The internal energy distribution undergoing collision-induced dissociation (CID) in the cell of a quadrupole ion trap (QIT) mass spectrometer can be characterized by the effective temperature, which would help determine the activation energy and entropy. Here, the relationship in a Bruker QIT has been reexamined based on kinetic measurements at two qz values. An observed linear relationship between ion effective temperatures and resonant activation amplitudes appears qualitatively different from simplified theoretical simulation, which is in agreement with previous results on Finnigan ion trap. However, the normalization process aiming to compensate for the m/z dependency of the required fragmentation energy that is used successfully in Finnigan-geometry traps is not entirely successful for use in Bruker-geometry trans. The calibration determined here roughly indicates the relationship between ion effective temperature, resonant excitation amplitude and ion m/z. However, Successful extraction of the dissociation energetics still requires a better accuracy of the calibration.

This book provides a concise overview of the photophysics and spectroscopy of bio chromophore ions. The book "Photophysics of Ionic Biochromophores" summarizes important recent advances in the spectroscopy of isolated biomolecular ions in vacuo, which has within the last decade become a highly active research field. Advanced instrumental apparatus and the steady increase in more and more powerful computers have made this development possible, both for experimentalists and theoreticians. Applied techniques described here include absorption and fluorescence spectroscopy, which are excellent indicators of environmental effects and can thus shed light on the intrinsic electronic structures of ions without perturbations from e.g. water molecules, counter ions, nearby charges, and polar amino acid residues. When compared with spectra of the chromophores in their natural environment, such spectra allow to identify possible perturbations. At the same time gas-phase spectra provide important benchmarks for quantum chemistry calculations of electronically excited states. This volume focuses on biological systems from protein biochromophores, e.g. the protonated Schiff-base retinal responsible for vision, and individual aromatic amino acids to peptides and whole proteins, studied using visible, ultraviolet and vacuum ultraviolet light. Work on DNA nucleotides and strands that are amenable to mass spectrometric studies because of the negatively charged sugarphosphate backbone are also presented. DNA strands represent an example of the interplay between multiple chromophores, which is even harder to model correctly than just single chromophores due to spatially extended excited states and weak coupling terms. The experimental techniques used to measure spectra and commonly used theoretical methods are described with a discussion on limitations and advantages. The volume includes an updated status of the field and interesting future directions such as cold ion spectroscopy.

Advances in Gas Phase Ion Chemistry

Optical spectroscopy combined with mass spectrometry provides a unique opportunity to probe the intrinsic properties of biologically-relevant ions in the gas phase, free from the interfering effects of solvent interactions in the condensed phase. Electrospray ionization allows large biomolecules to be transferred intact into the gas phase for mass analysis. Modern mass spectrometers provide excellent sensitivity, mass-resolution and can efficiently isolate a single ionic species from a complex mixture. However, the extent to which biomolecules retain their solution-phase conformations in the gas phase is largely unknown. Therefore, there is considerable interest in applying spectroscopic methods to biological ions in vacuuo. Due to the low number densities of ions in storage devices, traditional absorption measurements are not feasible, requiring more sensitive analytical methods. Two such techniques are laser-inducedfluorescence (LIF) and photo-dissociation (PD) action spectroscopy, both of which measure the consequence of absorption. The work in this dissertation describes applications of optical spectroscopic methods to interrogate mass-selected ions using a variety of ion storage apparatus including a Fourier transform ion cyclotron resonance mass spectrometer, a quadrupole ion trap and an electrostatic ion storage ring. First, the conformations of small cationized arginine complexes have been investigated using infrared multiple-photon dissociation (IRMPD) action spectroscopy in the IR fingerprint region of the spectrum (200-1800 cm-1). Second, an apparatus incorporating a quadrupole ion trap has been constructed in our laboratory to perform LIF and PD-action spectroscopy. The gas-phase fluorescence and photodissociation properties of three Rhodamine dyes have been investigated including fluorescence excitation and dispersed fluorescence spectra. Finally, the latter chapters describe the use of electronic action spectroscopy to investigate a model chromophore o.