Technical Developments

AM-CSIC group

FOLLOW-UP NEWS (Mid 2014)

New IR spectroscopy data in the laboratory in combination with theoretical modeling of solid structures and a detailed comparison with astronomical observations rule out the presence of pure and amorphous CO₂ ice in space (AM-CSIC team in national collaboration).

FOLLOW-UP NEWS (Feb 2013)

The AM-CSIC Group has completed the implementation of the spectroscopic capabilities of the ISAC ultra-high-vacuum chamber (ISAC stands for “Interstellar Astrochemistry Chamber) at the Centro de Astrobiología in order to perform medium and far-infrared spectroscopy. Such improvements have been achieved through the acquisition of several instrumentation and components:

• MgF₂ and CaF₂ windows: these are used for the sample deposition of interstellar and circunstellar mantle analogues (H₂O, CO, CH₃OH, CO₂, NH₃, …) as well as acetylene (C₂H₂) to study the possible formation of Polycyclic Aromatic Hydrocarbons (PAHs)
• CVD Diamond windows for ultra-high-vacuum: These will allow to make spectroscopy in ultra-high-vacuum conditions in the range between 250 nm to 30 cm^-1. Diamond windows reduce significantly absorption problems, fluctuations from the source emissivity and the intrisic weakness of the absorption bands
• Solid-state beam splitter: this accessory will be used to spread the spectral working range of the FTIR Vertex 70 spectrometer to the medium and far-infrared
• Raman spectrometer: implementation of Raman spectroscopy at the ISAC chamber. In-situ Raman spectroscopy of ice samples, together with the infrared spectroscopy, will allow to associate the far-infrared bands to a concrete ice structure, both amorphous and crystalline types. This method will characterise the structure of the ice mantles in the interstellar dense clouds and the circumstellar medium. Raman spectroscopy will also detect organic products even at cryogenic temperatures

GEM-UVA group

Implementation of a high-resolution Molecular Beam Fourier Transform – Microwave spectrometer in the centimeter and millimeter wave frequency range. The existing 4 – 18 GHz frequency range will be extended to cover 60 GHz. Implementation of static absorption spectrometer to reach the 1 THz frequencies. All these techniques will allow the measurements of the rotational spectra in molecules of astrophysical interest, including:

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FOLLOW-UP NEWS (feb 2013)

The LHM-UCM group has constructed a new molecular beam apparatus has been built as stated at the beginning of 2012 to produce intense anion beams and perform anion spectroscopy (see figure below). Preliminary photodetachment data of H^—₂ have been obtained. The group is working to increase the sensitivity of this technique with a multi pass mirror system for laser beam and the improvement of the pressure stability of the discharge. The first target will be C₅H^— (photodetachment and polarisation).

PAST NEWS (Feb 2012)
The LHM-UCM group have developed a molecular-beam setup to produce intense anion beams to be studied through high resolution spectroscopy (characterisation of the anion sources, mass spectra and anions deceleration). A general view of the experimental setup is shown below. A new source of high-voltage cathode discharge coupled to a supersonic expansion valve nozzle has been acquired.

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GFM-CSIC group

 

Incorporation of a high power pulsed laser and construction of a new plasma refrigerated reactor in order to measure low temperature (5 – 200 K) state-to-state collision rate coefficients from the rotational population evolution in supersonic gas jets. An experimental methodology to measure vibration-translation collision rate coefficients at high temperature, and fast kinetics and energy transfer in plasmas by pulsed excitation will also be developed.

FOLLOW-UP NEWS (Feb 2013)

• High-res Infrared Spectroscopy Laboratory: the setup for frequency measurements has been completed with the final acquisition of the wavemeter (delivered in September 2012). The fine tuning of the multi pass cell with hollow cathode discharge has been completed for the production of molecular ions. The goal is to obtain better vibration-rotation transition frequencies of molecular ions (see figure below).

• Cold Plasmas Laboratory: The ionic chemistry of various hydrogen mixtures (H₂/N₂, H₂/O₂, and H₂/air) has been studied in low-pressure hollow cathode discharges. The major ions identified in the different discharges (H⁺₃, N₂H⁺, H₃O⁺ and NH⁺₄) have been also found in astronomical observations or predicted in astrochemical models. These results support the predictions of some astrochemical models indicating that NH⁺₄ ions could be dominant in warm astronomical environments where H₂O and NH₃ molecules evaporate from dust grain mantles (see Publication number [85] in 2012 ASTROMOL Publications).
• Molecular Fluid Dynamics Laboratory: Five complete series of H₂O+He supersonic jets have been measured and analysed. The first experimental results of the inellastic collisional rates for ortho-H₂O with He at 100 K and 40 K are shown (see Publication: G. Tejeda et al., AIP Conf. Proc. 1501, 1305 (2012)).

PAST NEWS (Feb 2012)

• Cold Plasmas Laboratory: The high resolution visible spectrometer Jobin-Yvon FHR1000 has been acquired and adjusted. Several emission measurements of H₂ and H₂+N₂ discharges are in progress. An equipment for coupling effects in inductive discharges with radio frequency on a Pyrex shielded reactor is being adjusted in order to minimize the effects of reactions at the surface.
• High-res Infrared Spectroscopy Laboratory: The adjustment of the difference-frequency infrared spectrometer is in progress.
• Molecular Fluid Dynamics Laboratory: We have improved the source for water vapour in expansion chamber experiments with a sophisticated system to control the temperature, pressure and flux of the components. This allows to generate H₂O and its mixtures with He and H₂ controlled expansions in between 40 and 1000 mbar. The experimental set-up has been substantially improved with the acquisition of two high-capacity pumps.

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QYCA-UCLM group

 

Setting up of a pulsed Laval supersonic nozzle apparatus with laser-induced fluorescence detection for kinetic studies (CRESU)in order to achieve temperatures as low as 10 K. The characteristics of each Laval nozzle will be critical to reach a specific temperature range and that implies the desigh of several nozzles to cover the desired range of temperatures. The goal is the combination of two different techniques (discharge flow and CRESU) to investigate the temperature dependende of the reaction rates.

FOLLOW-UP NEWS (Feb 2013)

The pulsed CRESU experimental setup has been successfully completed. The setup will be validated through 2013 with the study of the reaction of OH with 1-butene at 23 K thus obtaining the first experimental results. See figure below to have a look at the whole experimental setup at the end of 2012.

PAST NEWS (Feb 2012)
The QYCA-UCLM group have designed the reaction chamber for the pulsed Laval supersonic nozzle apparatus (CRESU). The essential parts of the CRESU system are the spinning rotor gauge, the nozzle and the reaction chamber. The spinning rotor gauge and its engine, which will be coupled to the nozzle, have just been acquired. The acquisition of the nozzle and the chamber reaction, which are being developed at the University of Rennes I, will be completed in mid 2012. The experimental set-up is shown below.

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ABIDIN-CSIC group

 

Development of new time-dependant numerical codes to treat inellastic and reactive collisions involving more than 3 atoms. Extension of Quantum Statistical Methods to treat diatomic and triatomic reactions such as the HD + H₃⁺ ⇒ H₂D⁺ + H₂ isotopic exchange reaction. Development of ab initio methods to derive molecular structures, dipolar moments and theoretical rovibrational levels. Theoretical determination of energy levels and spectra of molecular clusters.

FOLLOW-UP NEWS (Feb 2013)

• Simulation of the infrared pre-dissociation spectrum of H₅⁺ (see publications number [54] and [55] in 2012 ASTROMOL Publications)
• Development of a dynamically biased statistical model to describe the evolution of the ortho/para conversion in the H₂ + H₃⁺ → H₃⁺ + H₂ reaction from statistical to a more direct mechanism, using quasi-classical trajectories (QCT) (see publication number [50] in 2012 ASTROMOL Publications)
• Study of the dynamics and kinetics of the Li + H₂⁺ reaction and its isotopic variants (D₂⁺ and T₂⁺) with the DINQUIM-UCM group. The calculated reaction rates will be used in astrophysical models (see publication number [59] in 2012 ASTROMOL Publications). The study of the dynamics and kinetics of the C⁺ + H₂ reaction with the AM-CSIC group will be published at the beginning of 2013.
• Calculation of the potential energy curves (including orbital-spin coupling) of the Ca⁺ + H, Mg + H and Sr + H systems in order to study the depolarisation of the Ca⁺(2P and 2D) electronic excited states in collisions with atomic hydrogen. Furthermore, such collisions have been studied through the development of programs to resolve coupled differential equations resulting from the Schrödinger equation and the depolarisation coefficients have been calculated. This work (2013) has been carried out together with the RT-IAC group.

PAST NEWS (Feb 2012)
The ABIDIN-CSIC group have reached the following goals:

• Calculation of the Potential Energy Surface of the H₅⁺ system, including all the degrees of freedom.
• Characterisation of bound states, the predissociative, vibrationally excited states involved in the electric dipole transitions of H₅⁺.
• Accurate time dependent wave packet calculations for the Li+HF, N+OH, O+HF y Li+H₂⁺ reactions. These results should have an important impact in the study of the chemistry of these molecules and their possible detection in the Interstellar Medium.

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LEMQC-UMU group

 

Development of empirical and ab initio methods to calculate the potential energy and dipolar moment functions of molecular species. Determination of global Potential Energy Surfaces (PESs) of inelastic systems for which global PESs are not available.

FOLLOW-UP NEWS (Feb 2013)

• Calculation of the pure rotational and vibration-rotation spectra of the NaCl and KCl molecules and their corresponding isotopic species by using both high-accurate potential energy curves and semiempirical dipole momentum functions.
• Calculation of the transition frequencies between highly-excited rotational and rovibrational states in linear triatomic molecules (CO₂ and N₂O) and their corresponding isotopic species. Extension to other triatomic molecules of astrophysical interest is foreseen throughout this year.

PAST NEWS (Feb 2012)
The LEMQC-UMU group have treated the theoretical characterisation of the rovibrational spectrum of linear triatomic molecules: N₂O, CO₂, FCN and HCN. Hence:

• The frequencies of rotational transitions for N₂O (main isotopologue: 14-14-16; isotopologue: 14-15-16) have been calculated.
• The spectroscopic constants G_v and B_v for CO₂ (isotopologue ¹⁶OCO; main isotopologue 16-12-16 and isotopologue 16-13-17), FCN (isotoplogue 19-13-14) have been calculated.
• The spectroscopic constants G_v and B_v for HCN together with the frequencies of rotational transitions have been calculated.

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