The benzylium and tropylium cations identified as two stable C7H7+ isomers

The picture, which is a cover of the journal ChemPhysChem, schematizes the production of the C7H7 ion by dissociative ionization of toluene and the identification, by infrared spectroscopy, of the two isomers produced: the cations benzylium (right) and tropylium (left).

Experiments driven by an international team involving the Institute for Research in Astrophysics and Planetary Sciences (IRAP, Université de Toulouse/CNRS) and the Laboratory of Quantum Chemistry and Physics (LCPQ, Université de Toulouse/CNRS), enabled to identify the two stable isomers of C7H7+ ion.

The ion C7H7is a well-known species in mass spectrometry, formed by ionization of hydrocarbons such as toluene. The two most stable structures proposed for this ion are benzylium and tropylium ions. The first (a benzene with a methylene group) could be identified by its chemical reactivity, but is not the case of the second, whose structure consisting of an aromatic cycle of 7 carbons is predicted by quantum chemistry calculations.

Two structures have been identified for C7H7+ and the vibrational spectra obtained are in agreement with those of benzylium and tropylium ions calculated with the density functional theory. In addition, measures in depletion helped to show that no other isomer was present and this for different precursors used in the production of C7H7+.

The study took advantage of the FELion line, installed on the free electron laser FELIX, in the Netherlands. FELion includes a cryogenic ion trap that allows attaching an atom of rare gas on the ions studied. This technique of tagging allows to implement a spectroscopy of action by dissociating the complexion/atom of rare gas with a single infrared photon unlike the technique usually used of multiple absorption of photons to attain the threshold of dissociation of the ion. This technique has the advantage to probe ions without heating them and so without disrupting their structure through processes of isomerization.

This work of identification of C7H7+ isomers opens up prospects for the study of the growth paths of the hydrocarbon ions in complex environments both on Earth (chemistry of flames, and plasmas) or space (interstellar chemistry and planetary atmospheres as Titan’s).

This interdisciplinary work (INSU/INP/INC) has been initiated as part of the ERC Synergy NANOCOSMOS project in collaboration with the CSIC (Madrid) and involves a collaboration between the universities of Toulouse and Cologne as part of the European Training Network (ETN) EUROPAH.

Scientific paper: 

P. Jusko, A. Simon, S.Banhatti, S. Brünken, C. Joblin (2018) DirectEvidence of the Benzylium and Tropylium Cations as the two long-lived Isomersof C7H7+, ChemPhysChem, doi:10.1002/cphc.201800744 – Archives ouvertes: hal-01880438, arXiv:1809.09375

Link to the INSU news page: Les cations de benzylium et tropylium identifiés comme les deux isomères stables de C7H7+


New Nanocosmos Doctor

Some news from the young team surrounding our PI from Toulouse, Christine Joblin. Sarah Rodríguez Castillo (third on the left, first row) presented on October 30th 2018 her PhD thesis entitled “Study on the dissociation of astro-PAHs”, that was carried out at the University of Toulouse/CNRS in the framework of the Nanocosmos projet.

Congratulations on this great achievement, Doctor!


Polycyclic Aromatic Hydrocarbons (PAHs) are revealed in astrophysical environments thanks to their characteristic infrared emission after these molecules are subjected to the vacuum ultraviolet (VUV) radiation from nearby massive stars. This interaction regulates their charge state, stability and dissociation mechanisms, which in turn affect the energy balance and the chemistry of the gas in the interstellar medium. In particular, PAHs could contribute to the formation of the most abundant molecule, H2, in photodissociation regions (PDRs). This work aims at contributing to these topics by quantifying the VUV photoprocessing of specific medium-sized PAH cations through experimental studies complemented by computational investigations.The experimental results were gathered from two campaigns at synchrotron facilities: ion trap experiments allowed us to obtain the yields of ionization and fragmentation and the branching ratios between the different photoevents, while from iPEPICO spectroscopy we obtained breakdown curves and RRKM-fitted dissociation rates. We detail the case of the fragmentation processes of two isomers of dibenzopyrene cation (C24H14+) in order to assess the impact of structure on these processes. We present Density Functional Theory calculations and Molecular Dynamics simulations, which evidence the relevance of structure and planarity in these mechanisms and provide a better view on the dissociation pathways and energetics.This work brings significant new data for models that describe the chemical evolution of PAHs in astrophysical environments, including the first measurement of the ionization yield of medium-sized PAH cations as well as several dissociation rates. We also report a new mechanism, involving specific structures with bay areas, that would need to be considered while evaluating the contribution of PAHs to the formation of H2 in PDRs.

The documentary about NANOCOSMOS nominated for BICC awards

BICC is the acronym for “XXIX Bienal Internacional de Cine Científico Ronda-Madrid-México 2018”, the biennial international event for science movies. Our documentary “NANOCOSMOS: Un viaje a lo pequeño” has been selected as finalist in this contest within the category of “Science documentary”.

We are very proud to do our bit in science communication!  Even if we don’t get any prize, we acknowledge the jury for considering our movie for the contest.  We will stay tuned for the date of the ceremony. Let’s cross fingers!

Link to the BICC press release (in Spanish).

Horizon Europe: The New Search and Innovation Framework Programme: Challenges and Opportunities

Next week NANOCOSMOS will be in the workshop “Horizon Europe: The New Search and Innovation Framework Programme: Challenges and Opportunities“, organized in the Universidad Menéndez Pelayo (UIMP) by the Ministry of Science, Innovation and Universities and the Spanish Science Research Council (CSIC) . With several panels, this meeting joins some of the relevant scientific and industrial players around new opportunities and challenges in Horizon Europe for the period 2021-2027. The program of the meeting overviews the three major pillars of the Commission’s proposal, covering all forms of innovation, global challenges through research and innovation for the uptake of innovative solutions in industry and society, as well as investigator driven high quality research and infrastructures.  NANOCOSMOS will be represented by one of its Principal Investigators, José Cernicharo, in the panel “The ERC in Horizon Europe – A Reflection on Interdisciplinarity and Multipotentialities.”

Ve la luz el documental “Nanocosmos: un viaje a lo pequeño”


El documental, que cuenta en formato road-movie los entresijos del nacimiento de los granos de polvo en el espacio, está financiado por la Fundación Española para la Ciencia y la Tecnología – Ministerio de Economía, Industria y Competitividad y el Consejo Superior de Investigaciones Científicas (CSIC) y ha sido producido por la empresa LuzLux.

Tras seis meses de trabajo, el equipo formado por personal de CSIC y la productora LuzLux, entre otros, ha finalizado el documental “Nanocosmos: un viaje a lo pequeño”, una película de carretera que habla del reto tecnológico y humano que hay tras el desarrollo de instrumentación en el área de la astrofísica de laboratorio.

La historia se desarrolla en tres planos: el viaje del equipo de grabación desde Madrid hasta Toulouse, los experimentos de laboratorio explicados por sus responsables y el propio viaje de los granos de polvo cósmico desde que nacen en la envoltura de una estrella evolucionada hasta que pasan a formar parte de algo mucho más grande (una estrella, un planeta o, por qué no, un ser vivo).

Este trabajo quiere transmitir las expectativas de los equipos que luchan por comprender este proceso, el reto tecnológico y humano que supone construir máquinas complejas y lograr reproducir en un laboratorio lo que ocurre en el espacio. El documental, de 40 minutos de duración, circulará por circuitos de cine científico y canales específicos de divulgación científica durante un año, tras lo que estará disponible en la página web de Nanocosmos.

En este enlace podrán ver el tráiler que anuncia el documental, que está disponible en español  con subtítulos en inglés y en francés. También hay una versión con subtítulos en español para personas con discapacidad auditiva.


After six months of work, the team formed by CSIC staff and the LuzLux production company, among others, has completed the documentary “Nanocosmos, un viaje a lo pequeño” (a journey to the origins of dust grains), a road movie which talks about the technological and human challenge that lies behind the development of instruments in the area of Laboratory Astrophysics.

The story unfolds in three levels: the journey of the recording team from Madrid (Spain) to Toulouse (France), the laboratory experiments explained by its principal investigators and the journey of the cosmic dust grains since they are born in the envelope of an evolved star until they become part of something bigger (a star, a planet or, why not, a living being).

This work wants to transmit the expectations of the teams struggling to understand this process, the technological and human challenge involved in building complex machines whith a goal: to reproduce in a laboratory what happens in space. The 40-minute documentary will circulate along circuits of scientific movies and specific science channels for a year, and after that it will be available on the Nanocosmos’ website.

In this link you can see the trailer announcing the documentary. The movie is available in Spanish with subtitles in English and French.