Laser Consortium Journal Clubs and Discussion Meetings

Tuesday, 4 March 2014

Allan: JC: Frequency-resolved optical gating capable of carrier-envelope phase determination

http://www.nature.com/ncomms/2013/131115/ncomms3820/full/ncomms3820.html

Recent progress of the coherent light synthesis technology has brought the generation of single-cycle pulses within our reach. To exploit the full potential of such a single-cycle pulse in any applications, it is highly important to obtain the full information of its electric field. Here we propose a novel pulse characterization scheme, which enables us to determine not only the intensity and phase profiles of ultrashort pulses but also their absolute carrier-envelope phase values. The method is based on a combination of frequency-resolved optical gating and electro-optic sampling, which can be extended to a self-referencing scheme to determine the electric field evolution of few-cycle ultrashort pulses. We have experimentally demonstrated the technique to characterize sub-single-cycle infrared pulses, and numerically studied the capability of the scheme to incorporate a self-referencing technique and to extend the wavelength range to visible region.

Tuesday, 25 February 2014

Lukas: JC: Femtosecond M2,3-Edge Spectroscopy of Transition-Metal Oxides: Photoinduced Oxidation State Change in a-Fe2O3

Femtosecond M2,3-Edge Spectroscopy of Transition-Metal Oxides: Photoinduced Oxidation State Change in a-Fe2O3

http://pubs.acs.org/doi/abs/10.1021/jz401997d?prevSearch=%255BContrib%253A%2Bstephen%2BLeone%255D&searchHistoryKey=

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.