Archive for the ‘News’ Category

The motion of the two electrons in the helium atom can be imaged and controlled with attosecond-timed laser flashes

Source: MAX-PLANCK-GESELLSCHAFT, MÜNCHEN
Original publication: 
Christian Ott, Andreas Kaldun, Luca Argenti, Philipp Raith, Kristina Meyer, Martin Laux, Yizhu Zhang, Alexander Blättermann, Steffen Hagstotz, Thomas Ding, Robert Heck, Javier Madroñero, Fernando Martín and Thomas Pfeifer

The last issue of XLIC Newsletter contains an overview on recent XLIC meetings (as the WG1 and WG3 meetings and the 2nd Annual Workshop held in Poland, past September 2014), news on forthcoming events, and several scientific highlights selected from the contributions received from XLIC participants.

You can now read it here.

The ab initio molecular dynamics code SHARC (Surface Hopping including ARbitrary Couplings) version 1.0 has been released. It is developed in the González group at the University of Vienna and its purpose is the investigation of excited-state dynamics.

SHARC

  • can treat non-adiabatic couplings at conical intersections, intersystem crossing induced by spin-orbit coupling, and laser couplings on an equal footing.
  • has interfaces to MOLPRO, MOLCAS, COLUMBUS (needs MOLCAS in this case), and analytical potentials.
  • includes auxilliary Python scripts for all steps of the setup procedure and for various analysis tasks.
  • has a comprehensive tutorial.

The developers invite you to try out the software and are looking forward to feedback. The code is free of charge for academic use.

Download and further information can be found on: http://sharc-md.org

Contact:
González group
University of Vienna. Institute of Theoretical Chemistry
Address: Währinger Str. 17, 1090 Wien. Austria
Email: sharc (at) univie.ac.at

Experimentalists involved in XLIC Action have been able to observe electron motion in a biological molecule on an attosecond timescale.

The work, reported in Science, was carried out using some of the shortest laser pulses in the world which were used as strobe lighting to track the ultrafast movement of the electrons within the nanometer-sized molecule. These attosecond laser pulses were used to initially stimulate the electrons and then to observe their resulting collective oscillations which lasted for 4300 attoseconds (billion-billionths of a second), the fastest process ever observed in a biological structure.

Explaining how electrons move on the nanoscale is crucial for the understanding of a range of processes in biology as it is this charge which initiates chemical reactions. For instance the charge produced from the interaction of ionizing radiation with DNA and its subsequent ultrafast excursions is crucial in determining the resulting damage to the DNA which can result in cell death or mutations. This knowledge is important for understanding the action of radiotherapy beams in cancer treatment.  img-expsetupBeing able to describe how light interacts with electrons on these timescales could also lead to the technological improvements such as solar cells which collect electrons more efficiently or faster microprocessors which use light rather than electrical signals for switching transistors.

The attosecond laser used to measure the electron dynamics in phenylalanine was developed at the Politecnico di Milano by Professor Mauro Nisoli and the study of electrons in biomolecules has since 2012 been the product of a collaboration with Ultrafast Belfast.

Check out more here:

 

By using attosecond pulses to promptly ionize the amino acid phenylalanine, several European researchers involved within XLIC Action have detected an ultrafast response of purely electronic origin, which is characterized by a charge oscillation with two main frequency components corresponding to periods of 2.8 fs and 4.2 fs. Electron dynamics in biomolecules on a temporal scale preceding nuclear motion is at the heart of many biological processes. This work has been published in Science.

This mixed experimental/theoretical work, undertaken by researchers from Milano, Madrid, Belfast and Trieste, has found clear experimental evidence of ultrafast charge dynamics in the phenylalanine amino acid, after prompt ionization induced by attosecond pulses. Charge migration shows up as oscillations in the yield of a doubly-charged molecular fragment produced from ionization of a second electron by a probe pulse as a function of its delay time. Two main frequencies were measured: 0.24 PHz (corresponding to a period of 4.2 fs) and 0.36 PHz (period of 2.8 fs), thus confirming the electronic origin of the measured dynamics. Numerical simulations of the temporal evolution of the electronic wave packet created by the attosecond pulse strongly support the interpretation of the experimental data in terms of charge migration.

The ability to initiate and observe purely electronic dynamics in the building blocks of life represents a crucial step forward in attosecond science, which is progressively moving towards the investigation of more and more complex systems and can be considered as a first contribution towards attobiology.

Direct measurement of the ultrafast charge dynamics in an amino acid, initiated by attosecond pulses, represents a crucial benchmark for the extension of attosecond methodology to biology. In the same way in which femtosecond pulses have contributed (and still contribute) to the investigation and understanding of important biological processes, attosecond science offers the possibility to elucidate, on a temporal scale preceding nuclear motion, subtle processes ultimately triggering and determining the response of biomolecules. img-HoleDynamicsFor instance, how the ultrafast motion of a hole in DNA created by a high-energy particle might initiate cell necrosis or mutation. The results obtained in the case of phenylalanine can be seen as the first experimental confirmation that attosecond pulses and techniques will be essential tools for understanding of dynamical processes on a temporal scale that is relevant for the evolution of crucial microscopic events at the heart of the macroscopic biological response of molecular complexes.

This study has been conducted by the following XLIC nodes:

  • IFN-CNR and Politecnico di Milano (Italy). Groups led by Francesca Calegari and Prof. Mauro Nisoli, PI of the ERC-AdG-ELYCHE project (GA nº 227355)
  • Universidad Autonoma de Madrid and IMDEA-Nanociencia (Spain). Group led by Prof. Fernando Martín, PI of the ERC-AdG-XCHEM project (GA nº 290853)
  • Center for Plasma Physics, QUB.(Dr. Jason Greenwood)
  • Università di Trieste and CNR-IOM. (Dr. Piero Decleva)

Ref. Ultrafast electron dynamics in phenylalanine initiated by attosecond pulses
F. Calegari, D. Ayuso, A. Trabattoni, L. Belshaw, S. De Camillis, S. Anumula, F. Frassetto, A. Palacios, P. Decleva, J. B. Greenwood, F. Martín, M. Nisoli
Science 346, 336-339 (2014). DOI:10.1126/science.1254061

The 1st XLIC Young Scientist Forum has been held during the 2nd  XLIC General Meeting in Gdansk University of Technology (Gdansk, Poland).

It was a special half-day with talks given by  young researchers (PhD students and post-docs). The committee of young researchers selected, on the basis of submitted abstracts, the following young speakers to give a talk at the YSF. The list is given in  alphabetical order:

  • Cedric Bomme, FLASH, Germany
  • Michael Capron, Univerty of Rennes, France
  • Aurélie Chenel, Université Paris-Sud, France
  • Simone De Camilis, Queen’s University Belfast, UK
  • Ewa Erdmann, Gdansk University of Technology, Poland
  • Tor Kjellsson, Stockholm University, Sweden
  • Sylvain Maclot, Université de Caen Basse-Normandie, France
  • Ana Martín Sómer, Universidad Autónoma de Madrid, Spain
  • Lihi Musbat, Bar Ilan universityk, Israel
  • Geert Reitsma, University of Groningen, Netherlands
  • Estefania Rossich Molina, Université Evry Val d’Essonne, France
  • Janne Solanpää, Tampere University of Technology, Finland

jangiYoung researchers participating at XLIC General Meeting also had the opportunity to present their results as a poster. Two poster sessions were foreseen in order to exchange views and stimulate discussions on research topics, and to support interdisciplinary communication between the researchers.

 

The 2nd General Meeting of the COST Action CM1204 “XUV/X-ray light and fast ions for ultrafast chemistry (XLIC)” was held from 10th to 12th of September, 2014 in Poland. Gdansk University of Technology hosted 91 guests from 22 countries. It is important to note that almost half of participants where PhD Students or Early Stage Researchers.

This three-day meeting was divided into nine speaking sessions, two of them taken by young researchers. This two sessions composed the 1st Young Scientists Forum of COST Action, where young scientists presented 12 talks selected from a set of send proposals. Other 24 lectures were given by invited speakers. From scientific point of view our meeting was very fruitful and many talks were provided by experimentalists. Some new collaborations have been set.

DSC_8573_fullAt the end of the first day, there was the XLIC Management Committee meeting and there were two  poster sessions with 84 poster contributions.

Final meeting program, participants list and book of abstracts can be downloaded following the links below.

The Local Organiser,
Józef E. Sienkiewicz
Gdańsk University of Technology, Poland
e-mail: jes@mif.pg.gda.pl

and Local organizing committee:
– Justyna Ksionek (conference office: jksionek@mif.pg.gda.pl)
– Ewa Erdmann
– Julien Guthmuller
– Jan Franz
– Patryk Jasik
– Tymon Kilich
– Marta Łabuda
– Magdalena Staniszewska
– Paweł Syty
– Marcin Wiatr
at Gdańsk University of Technology, Faculty of Applied Physics and Mathematics, ul. Narutowicza 11/12, 80-233 Gdańsk, Poland.

Related links:

The Quantum Electronics and Optics Division (QEOD) of the European Physical Society (EPS) is soliciting nominations for its biennial prize

                                            Research into the Science of Light

to be presented at the Nanometa Conference organized in Seefeld, Austria, between the 5th and 8th of January, 2015. This meeting will start the EPS-supported European Conferences for the International Year of Light.

                    Nominations will be received online until October 1st, 2014.

The EPS Prize for Research into the Science of Light is a major prize awarded in recognition of a recent work by one or more (up to three) individuals for scientific excellence in the area of electromagnetic science in its broadest sense, across the entire spectrum of electromagnetic waves.

The work for which the individual(s) is/are nominated must be such that a significant component of it was performed during the 5 years prior to the award. In addition, the award recognises research for which a significant portion of the work was carried out in Europe or in cooperation with European researchers. It may be given for either pure or applied research.

The award will be accompanied by an engraved glass medal, a certificate, and a monetary sum of 2000 euros.

Nomination packets will consist of a CV and publication list of the nominee(s), a 2 page summary of the significance of the work subject of the nomination, a suggested citation, and up to 4 letters of support. All material must be prepared in English, combined into either a single consolidated PDF file or a ZIP archive, and submitted through the link:

http://qeod.epsdivisions.org/Research_into_the_Science_of_light_Prize_2015/

European Physical Society
http://www.eps.org

An updated version of the 2nd XLIC General Meeting programme (including poster contributions) has been published. Check it here

Looking forward to see you in Gdansk!!

In selected spectral regions, the UV fission of the bond between a carbon and a halogen atom in haloalkanes can happen explosively, in timescales of the order of tens of femtoseconds. Tunable ultrashort laser pulses like those available at the CLUR (Centre for Ultrafast Lasers, at the Complutense University of Madrid) in combination with velocity map imaging techniques are necessary to follow this type of photoinduced reactions in real time.

A team of Spanish researchers involved in the XLIC Action has demonstrated a powerful scheme that goes beyond the description of the reaction, and is capable of controlling its course. The mechanism involves employing an additional “control” laser pulse that modifies (“dresses”) the potential energy surfaces, producing changes in the outcome of the reaction and the speed of the fragments. Theoretical simulations have shown how the essential new tool for the maximum degree of control is to provoke rapid changes between the field-free regime and the “dressed states” regime.

Figure NatChem

This work demonstrates that fine control of the properties of this “control” laser pulse turns it into a true “photonic scalpel” capable of manipulating chemical reactions, as well as shedding new light into the dynamics of complex molecular dynamical processes.

Their work has been published in the journal Nature Chemistry on July 20, 2014.

M. E. Corrales, J. González-Vázquez, G. Balerdi, I. R. Solá, R. de Nalda, L. Bañares, Control of ultrafast molecular photodissociation by laser field induced potentials, Nature Chemistry (2014), doi:10.1038/nchem.2006

For more information, please check: