Julia LaskinChief Scientist, Fundamental and Computational Sciences Directorate, Chemical and Material Sciences Division, Chemical Structure and Dynamics
http://emslbios.pnl.gov/id/laskin_j Updated: December 6, 2010
Activation and Dissociation of Large Ions in Mass Spectrometry
The general objective of our research is to achieve a fundamental understanding of the reaction kinetics and dynamics of activating and dissociating complex molecular ions. These processes are the scientific foundation for tandem mass spectrometry, one of the most important analytical methods developed in the last century. We investigate the collisional activation and dissociation of protonated model peptides, a particularly important class of complex molecules whose characterization by tandem mass spectrometry is central to the emerging field of proteomics. Collisional activation of large ions in a single collision with a specially prepared surface - surface-induced dissociation (SID) - is a promising method for investigating fundamental questions of ion activation and may be a preferred method for practical applications, especially in Fourier Transform Ion Cyclotron Resonance mass spectrometry (FT-ICR MS).
We investigate the dynamics of SID of large molecules and the influence of physical and chemical properties of SID targets on the efficiency energy transfer into complex ions using time- and collision energy-resolved measurements in FT-ICR MS. Theoretical modeling of experimental data provides information on the energetics and dynamics of complex ion dissociation processes. In particular we focus on
1) understanding the transition from statistical to non-statistical fragmentation (shattering) in large ions;
2) comparison of dissociation energetics of covalent bonds in protonated species and the corresponding radical cations;
3) the energetics and dynamics of dissociation of non-covalent bonds in large floppy ions.
Soft-Landing of Peptide Ions on Surfaces
Interaction of ions with surfaces is an area of active fundamental research in surface science relevant to a broad range of other scientific disciplines such as materials science, mass spectrometry, imaging and spectroscopy. Two major processes are dominant for low-energy (0-100 eV) ion-surface collisions: reactive and non-reactive scattering of ions and ion loss on the surface as a result of neutralization or soft-landing (SL) of projectile ions. SL and a related process of reactive landing (RL) of ions, in which ion is covalently attached to the surface, are unique processes that occur during collisions of low-energy ions with self-assembled monolayer (SAM) surfaces. Exposure of surfaces to ions of known mass and composition presents a highly specific approach for surface modification relevant for a variety of applications in material science and biotechnology.
Fundamental studies on SL of peptide ions are carried out in collaboration with Prof. Graham Cooks's group (Purdue) using the newly developed capability to conduct secondary ion mass spectrometry studies in FT-ICR MS. In addition, deposition of large ions on surfaces is studied using a novel ion deposition chamber. Physical and chemical characterization of surfaces following SL or RL is carried out using a range of surface characterization techniques available at EMSL including surface probe microscopy (AFM/STM/EFM), TOF-SIMS, FT-ICR SIMS, and infrared reflection spectroscopy (IRRAS).
Analysis of Secondary Organic Aerosols
Another recent area of research is related to characterization of chemical composition of secondary organic aerosols (SOA). In particular, we are interested in understanding kinetics and mechanisms of formation of large organic polymers that constitute a significant fraction of SOA, identification of their chemical structure, and studying the effect of these polymers on physical properties of aerosols relevant to climate change.
Ph.D. in Physical Chemistry, The Hebrew University of Jerusalem, Israel, 1998
M.Sc. in Physics, Leningrad Polytechnical Institute, Russia, 1990
Awards, Honors, & Appointments
Sara Wolf Foundation Award in Physical Chemistry, The Hebrew University of Jerusalem, 1995
Excellence Award of the Israel Chemical Society, 1996
Award of the Farkas Center for Light Induced Processes, The Hebrew University of Jerusalem, 1997
M. T. Thomas Award for outstanding postdoctoral achievment, 2002
Presidential Early Career Award (PECASE), 2007
DOE's Office of Science Early Career Scientist and Engineer Award, 2007
DOE's Office of Science outstanding mentor award, 2008
Biemann Medal - American Society for Mass Spectrometry , 2008