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A study on charged fullerenes embedded in helium nanodroplets confirms their existence in interstellar space

Irradiation with pulses of infrared light of fullerene ions embedded in liquid helium nanodroplets has revealed transitions between the solid, liquid and superfluid phases of the helium layers surrounding the charged fullerene. The accuracy of these measurements, performed in an environment similar to that found in interstellar space, confirms the presence of fullerenes in space and opens the door to the characterization of diffuse interstellar clouds associated with other species rich in carbon.

Helium nanodroplets provide a unique tool for the study of properties of molecules under conditions similar to those found in interstellar space: low temperatures and almost total absence of interaction with the environment. The latter is the consequence of the superfluidity of liquid helium, which prevents embedded molecules to experience any friction when they move inside. However, the introduction of charged molecular species inside these nanodroplets produces substantial modifications in the latter, especially in the first layers of solvation around the charged molecule.

Using photoelectron spectroscopy techniques in combination with molecular dynamics calculations, the properties of the first helium layers that form around the C60+ fullerene have been studied in the framework of a wide international collaboration involving researchers from Universidad Autónoma de Madrid, IMDEA-Nanoscience and IFIMAC Condensed Matter Physics Center. The results demonstrate the appearance of phase transitions in the first helium layers as the number of helium atoms increases. In particular, it is observed a transition from a solid phase of helium (usually referred to as the “Atkins snowball”, see figure), to a liquid phase, when the second layer begins to form, and finally to the superfluidity phase. All this happens before reaching a hundred helium atoms. The precision required to reveal such changes is of the order of 0.05 nanometers, which explains why such phenomena have gone unnoticed to date.

Given the insulation and low temperature environment provided by helium nanodroplets, the method has confirmed the assignment of two diffuse interstellar bands (DIB) to the presence of the C60+ ion in space, which demonstrates the important role of fullerenes as a carbon reservoir in the universe. The work published in the journal Nature Communications shows that, with the accuracy achieved in this study, the absorption spectra of other astrophysically relevant species can be determined, such as smaller fullerenes, polycyclic aromatic hydrocarbons and their derivatives.

 

noticia-fulerenos

Figure 1. The measurement principle. Fullerene C60+ (whose carbon atoms are represented by black spheres), surrounded by an “Atkins snowball” formed by a layer of helium atoms (transparent spheres surrounding the C60+), is irradiated by a laser pulse of infrared light, which leads to the evaporation of helium atoms. The wavelength of the absorbed light depends on the number of helium atoms initially adsorbed on the C60+.

 

Reference:

Atomically resolved phase transition of fullerene cations solvated in helium droplets
M. Kuhn, M. Renzler, J. Postler, S. Ralser, S. Spieler, M. Simpson, H. Linnartz, A.G.G.M. Tielens, J. Cami, A. Mauracher, Y. Wang, M. Alcamí, F. Martín, M.K. Beyer, R. Wester, A. Lindinger & P. Scheier
Nat. Commun. 7, 13550 doi: 10.1038/ncomms13550 (2016)

 

 

Course on Parallel Programming with OpenMP and MPI

A new edition of the course on Parallel Computing will be held next November 2nd, 2016. The goal of the course is the understanding and practice fundamental concepts about parallel programming with OpenMP  and MPI.

More information here

parallel-computing

 

PhD fellowships -ITN-EJD: Theoretical Chemistry and Computational Modelling TCCM

A Consortium of 12 European Universities and 14 associated partners, including 9 private companies, under the coordination of the Universidad Autonoma of Madrid, offers 15 fully-funded 3-year PhD fellowships within the European Joint Doctorate Program in Theoretical Chemistry and Computational Modelling (EJD-TCCM), funded under the framework of the Innovative Training Networks of the Marie Sklodowska-Curie Action ITN-EJD-642294. TCCM. A detailed list of the projects and the institutions involved can be consulted on our website.

We offer

  • A 3-year European Joint Doctorate with cross-disciplinary thesis research in a stimulating, international scientific environment.
  • Working in top European Universities in at least two different countries
  • Supervision and mentorship by a team of internationally renowned experts.
  • Advanced training (scientific, transferable skills, career orientation) opportunities in English.
  • 2-10 month placement in private companies
  • An employment contract with full social security coverage

How to Apply

Applications must be submitted online at our website.

Deadline: 15th April 2015. PhD projects start in summer/autumn 2015. We look forward to hearing from you!

 

PhD and Postdoctoral positions on Theoretical Attosecond Molecular Dynamics

The Universidad Autónoma de Madrid (UAM) offers several postdoc and PhD positions linked to the ERC Advanced Grant project X-Chem (XUV/X-ray lasers for ultrafast electronic control in molecules), starting no later than September, 2015. The successful applicants shall develop a research project on “Theoretical Attosecond Molecular Dynamics” to theoretically investigate the coupled electron and nuclear dynamics induced by attosecond laser pulses and strong electromagnetic fields on small and mid-size molecules. The work will be performed in close collaboration with experimental groups.

More information can be found here

Prospect candidates must have an adequate degree in Physics or Chemical Physics and strong background in atomic, molecular and optical physics, attosecond physics, scattering theory, numerical methods, and programming. Transnational mobility will be positively evaluated.

Application procedure

Interested candidates are kindly requested to check all details about the application procedure for  PhD positions and  post-doc positions.

Applications not complying with the call guidelines may be discarded.

Deadline for Postdoc applications: February 15th, 2015

Deadline for PhD applications: March 15th 2015

 

Postdoctoral position opened in quantum chemistry

A one-year postdoctoral contract is available in the Campus group.The aim of the project is to develop a theory for the description of dynamical processes involving energy and charge transfer in molecule-surface interactions. The project involves the use state-of-the-art methodologies to study these complex processes in periodic systems.

Requirements:

  1. Hold a PhD in Physics or Chemical Physics
  2. Strong background in quantum chemistry, including the modeling of electronic excited states
  3. Experience in FORTRAN programming, treatment of periodic systems and/or dynamical calculations will be positively considered

The postdoc position will start between March 1st and June 1st 2015.

Further information can be found here:

The deadline for applications is February 1st 2015.

 

Ultrafast Electron Dynamics in a Biomolecule Initiated by Attosecond Pulses

Several european researchers have been able to induce and measure an ultrafast charge migration in a complex molecule. This phenomenon precede any structural rearrangement of molecules and is the basis of many biological processes. The work has been published in the journal Science.

The work arises from a cooperation among several European researchers. A clear experimental evidence of ultrafast charge dynamics in the phenylalanine amino acid, after prompt ionization induced by attosecond pulses, has been found. 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 theoretical work has been done by David Ayuso, Alicia Palacios and Fernando Martín, from the CampuS group.

 

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Master

Our group belongs to the Erasmus Mundus European program, which offers opportunities to obtain a master to European and non-European students. More details in Jobs.

 

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