| Autor: |
Vignoli Muniz GS; 1 Centre de Recherche sur les Ions, les Matériaux et la Photonique, Normandie Univ , ENSICAEN, UNICAEN, CEA, CNRS, CIMAP, Caen, France ., Mejía CF; 1 Centre de Recherche sur les Ions, les Matériaux et la Photonique, Normandie Univ , ENSICAEN, UNICAEN, CEA, CNRS, CIMAP, Caen, France .; 2 Departamento de Física, Pontifícia Universidade Católica do Rio de Janeiro , Rio de Janeiro, Brazil ., Martinez R; 1 Centre de Recherche sur les Ions, les Matériaux et la Photonique, Normandie Univ , ENSICAEN, UNICAEN, CEA, CNRS, CIMAP, Caen, France .; 3 Departamento de Física, Universidade Federal do Amapá , Macapá, Brazil ., Auge B; 1 Centre de Recherche sur les Ions, les Matériaux et la Photonique, Normandie Univ , ENSICAEN, UNICAEN, CEA, CNRS, CIMAP, Caen, France ., Rothard H; 1 Centre de Recherche sur les Ions, les Matériaux et la Photonique, Normandie Univ , ENSICAEN, UNICAEN, CEA, CNRS, CIMAP, Caen, France ., Domaracka A; 1 Centre de Recherche sur les Ions, les Matériaux et la Photonique, Normandie Univ , ENSICAEN, UNICAEN, CEA, CNRS, CIMAP, Caen, France ., Boduch P; 1 Centre de Recherche sur les Ions, les Matériaux et la Photonique, Normandie Univ , ENSICAEN, UNICAEN, CEA, CNRS, CIMAP, Caen, France . |
| Abstrakt: |
The presence of nucleobases in carbonaceous meteorites on Earth is an indication of the existence of this class of molecules in outer space. However, space is permeated by ionizing radiation, which can have damaging effects on these molecules. Adenine is a purine nucleobase that amalgamates important biomolecules such as DNA, RNA, and ATP. Adenine has a unique importance in biochemistry and therefore life. The aim of this work was to study the effects of cosmic ray analogues on solid adenine and estimate its survival when exposed to corpuscular radiation. Adenine films were irradiated at GANIL (Caen, France) and GSI (Darmstadt, Germany) by 820 MeV Kr 33+ , 190 MeV Ca 10+ , 92 MeV Xe 23+ , and 12 MeV C 4+ ion beams at low temperature. The evolution of adenine molecules under heavy ion irradiation was studied by IR absorption spectroscopy as a function of projectile fluence. It was found that the adenine destruction cross section (σ d ) follows an electronic stopping power (S e ) power law under the form: CS e n ; C is a constant, and the exponential n is a dimensionless quantity. Using the equation above to fit our results, we determined σ d = 4 × 10 -17 S e 1.17 , with S e in kiloelectronvolts per micrometer (keV μm -1 ). New IR absorption bands arise under irradiation of adenine and can be attributed to HCN, CN - , C 2 H 4 N 4 , CH 3 CN, and (CH 3 ) 3 CNC. These findings may help to understand the stability and chemistry related to complex organic molecules in space. The half-life of solid adenine exposed to the simulated interstellar medium cosmic ray flux was estimated as (10 ± 8) × 10 6 years. Key Words: Heavy ions-Infrared spectroscopy-Astrochemistry-Cosmic rays-Nucleobases-Adenine. Astrobiology 17, 298-308. |
