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Tuesday, 18 February 2014

Marina: DM: Laser mass spectroscopy

Mass spectrometry is the major physical method for structure determination of organic and biological molecules. The principle of this technique is generation, fragmentation and mass analysis of gaseous charged species using a variety of mass analysers (e.g. TOF, ion trap) to provide key information about the ion structure. The tremendous growth in application of mass spectrometry for detection, quantification and characterisation of molecules, especially of those of clinical interest (such as proteins), has stimulated exploration of new ionisation/dissociation techniques to enable reliable and comprehensive mass spectral analysis. Photodissociation at various light wavelengths, implemented on both ion trapping and TOF mass spectrometers, was shown to be one of the most powerful ion activation technologies. In particular, the recently introduced femtosecond laser-induced ionisation/dissociation (fs-LID) holds high promise for protein structural analysis delivering both the nonergodic ion dissociation and the indifference to the peptide molecular ion charge state. In this technique, coherent evolution of coupled many-electron and nuclear wavepackets is taking place causing an ultrafast macromolecule electron loss via the tunneling ionisation mechanism, on a timescale similar to or faster than that of bond vibrations, resulting in multiple series of peptide product ions in the mass spectra. I will discuss the laser MS technology, ion trap mass spectral instrumentation and will tell you about our plans to develop the first-of-its-kind two-dimensional femtosecond laser mass spectrometry for molecular structure determination on the basis of the covariance mapping of laser induced trapped fragments.