Radiolysis of Amino Acids by Heavy and Energetic Cosmic Ray Analogs in Simulated Space Environments: α\alpha-Glycine Zwitterion Form

In this work, we studied the stability of the glycine molecule in the crystalline zwitterion form, known as {\alpha}-glycine ($^{+}$NH$_{3}$CH$_{2}$COO$^{-}$) under action of heavy cosmic ray analogs. The experiments were conducted in a high vacuum chamber at heavy ions accelerator GANIL, in Caen, France. The samples were bombarded at two temperatures (14 K and 300 K) by $^{58}$Ni$^{11+}$ ions of 46 MeV until the final fluence of $10^{13}$ ions cm$^{-2}$. The chemical evolution of the sample was evaluated in-situ using Fourrier Transformed Infrared (FTIR) spectrometer. The bombardment at 14 K produced several daughter species such as OCN$^-$, CO, CO$_2$, and CN$^-$. The results also suggest the appearing of peptide bonds during irradiation but this must be confirmed by further experiments. The halflives of glycine in Interstellar Medium were estimated to be 7.8 $\times 10^3$ years (300 K) and 2.8 $\times 10^3$ years (14 K). In the Solar System the values were 8.4 $\times 10^2$ years (300 K) and 3.6 $\times 10^3$ years (14 K). It is believed that glycine could be present in space environments that suffered aqueous changes such as the interior of comets, meteorites and planetesimals. This molecule is present in proteins of all alive beings. So, studying its stability in these environments provides further understanding about the role of this specie in the prebiotic chemistry on Earth.Comment: 28 pages, 12 figures, 9 tables. Accepted to be published at Monthly Notices of the Royal Astronomical Society (MNRAS

Employing Soft X-rays in Experimental Astrochemistry

The presence of soft x-rays is very important for the chemical evolution of interstellar medium and other astrophysical environments close to young and bright stars. Soft X-rays can penetrate deep in molecular clouds and protostellar disks and trigger chemistry in regions in which UV stellar photons do not reach. The effects of soft X-rays in astrophysical ices are also remarkable because they release secondary electrons in and on the surface of the ices, which trigger a new set or chemical reactions. In this chapter we will discuss firstly about the origin and relevance of soft X-rays in astrophysics. Next we will move to the effect of ionizing radiation in organic molecules present in astrophysical environment. We will discuss the use soft X-rays in astrochemistry laboratory studies at both gas- and solid-phase (ice). We will make a review covering our publications in this field, in particular, about the experiments employing time-of-flight spectroscopy (TOF-MS), Fourier transform infrared (FTIR) spectroscopy and photon stimulated ion desorption (PSID-TOF-MS). This study help us to understand the chemical evolution several astrophysical regions and also put constrains in the researches related with the life's origin.Comment: 34 pages, 25 figures and 2 tables. This a book chapter of "X-Ray Spectroscopy" ISBN:978-953-307-967-7; InTech Open Access Publisher (http://www.intechweb.org/). Edited by Shatendra K. Sharma. Publication date: December 201

SOBREVIVÊNCIA DA MOLÉCULA ORGÂNCIA CH3OH EM REGIÕES DE ESTRELAS JOVENS

A molécula de CH3OH é uma das espécies orgânicas mais abundantes no meio interestelar e importante precursor de espécies pré-bióticas. Nesse trabalho estudamos sua sobrevivência em um cenário típico de estrela jovem, na presença de um campo de radiação ultravioleta (UV) entre 91.2 – 205 nm. Para isso usamos o código de transferência radiativa RADMC-3D para calcular os perfis de densidade e intensidade média de fótons em toda parte do modelo. Através desses resultados, usamos a seção de choque de destruição do CH3OH na região do ultravioleta para calcular sua taxa de fotodissociação e tempo de meia vida. Concluímos que no interior do disco, a molécula pode sobreviver intacta e ser liberada para a fase gasosa por processos não-térmicos. Porém no envelope, a fotodissociação é predominante, podendo formar espécies como HCOOCH3, HOCH2CHO e CH3CH2OH

COMPREENDENDO A FORMAÇÃO DE NANOESTRUTURAS EM GELO ASTROFÍSICOS ATRAVÉS DA DINÂMICA MOLECULAR CLÁSSICA

Gelos astrofísicos (formados pela água, entre outras moléculas) atuam como um catalisador e um reservatório de espécies carbonáceas, ambas com grandes implicações para a astrobiologia. Neste trabalho, nós estudamos a formação de nanoestruturas de gelo astrofísico encontradas no meio interestelar, tendo uma folha de grafeno como substrato catalisador, utilizando-se a técnica de dinâmica molecular clássica para modelar esses ambientes astrofísicos. Para isso, projetou-se dois sistemas: o primeiro composto por grafeno e  e o segundo composto por grafeno,  e . Inicialmente construiu-se uma caixa de simulação onde a área foi delimitada pelo grafeno cuja altura variava de 4, 6, 8 e 10 nm. As moléculas foram distribuídas uniformemente por toda a caixa. A técnica de dinâmica molecular provou ser uma ferramenta promissora para entender o fenômeno da adsorção de moléculas no substrato, permitindo-nos perceber que a distribuição aleatória de moléculas no sistema interfere com a estrutura geométrica formada por uma nanoestrutura de gelo. Este estudo nos permite compreender, do ponto de vista nanométrico, a influência de alguns parâmetros físico-químicos, no que tange a formação das nanoestruturas de gelos astrofísicos, como o número de ligações de hidrogênio, o tamanho inicial da caixa de simulação, e sua densidade durante o processo de congelament

Production of Oxidants by Ion Bombardment of Icy Moons in the Outer Solar System

Our groups in Brazil, France and Italy have been active, among others in the world, in performing experiments on physical-chemical effects induced by fast ions colliding with solids (frozen gases, carbonaceous and organic materials, silicates, etc.) of astrophysical interest. The used ions span a very large range of energies, from a few keV to hundreds MeV. Here we present a summary of the results obtained so far on the formation of oxidants (hydrogen peroxide and ozone) after ion irradiation of frozen water, carbon dioxide and their mixtures. Irradiation of pure water ice produces hydrogen peroxide whatever is the used ion and at different temperatures. Irradiation of carbon dioxide and water frozen mixtures result in the production of molecules among which hydrogen peroxide and ozone. The experimental results are discussed in the light of the relevance they have to support the presence of an energy source for biosphere on Europa and other icy moons in the outer Solar System.This research has been supported by the European COST Action CM0805: The Chemical Cosmos.Boduch, P.; Da Silveira, EF.; Domaracka, A.; Gomis Hilario, O.; Lv, XY.; Palumbo, ME.; Pilling, S.... (2011). Production of Oxidants by Ion Bombardment of Icy Moons in the Outer Solar System. Advances in Astronomy. 1-10. doi:10.1155/2011/327641S11

The temperature effect on the glycine decomposition induced by 2 keV electron bombardment in space analog conditions

Glycine is the simplest proteinaceous amino acid that has been extensively detected in carbonaceous meteorites and was recently observed in the cometary samples returned to Earth by NASA’s Stardust spacecraft. In space, such species is exposed to several radiation fields at different temperatures. In aqueous solutions, this species appears mainly as zwitterionic glycine (+NH3CH2COO−) however, in solid phase, it may be found in amorphous or crystalline forms. Here, we present an experimental study on the destruction of two zwitterionic glycine crystals (α- and β-form) at two different temperatures (300 K and 14 K) by 2 keV electrons in an attempt to test the behavior and stability of this molecular species in different space environments. The samples were analyzed in situ by Fourier transform infrared spectrometry at electron fluences. The experiments were carried out under ultra-high vacuum conditions at the Molecular Physics Laboratory at the Open University at Milton Keynes, UK. The dissociation cross section of glycine is approximately 5 times higher for the 14 K samples when compared to the 300 K samples. In contrast, no significant differences emerged between the dissociation cross sections of α- and β-forms of glycine for fixed temperature experiments. We therefore conclude that the destruction cross section is more heavily dependent on temperature than the phase of the condensed glycine material. This may be associated with the opening of additional reaction routes in the frozen samples involving the trapped daughter species (e.g. CO2 and CO). The half-life of studied samples extrapolated to space conditions shows that glycine molecules on the surface of interstellar grains has less survivability and they are highly sensitive to ambient radiations, however, they can survive extended period of time in the solar system like environments. Survivability increases by a factor of 5 if the samples are at 300 K when compared to low temperature experiments at 14 K and is independent of the crystalline structure. In addition, this survival would increase if the molecular species were protected by several layers of other molecular species as trapped in comet mantles or embedded within regolith in asteroids/lunar surfaces. The understanding of the excitation and dissociation processes of organic compounds in space simulation is highly required to put constrains in the puzzle over the origin of life in the primitive Earth

Mid infrared optical constants and porosity of H2O:CH4 ices at 30 K

XI RNO, Universidad de Salamanca, Salamanca (España), 1 - 4 Septiembre, 2015; http://rno11.usal.es/programaPeer Reviewe