Ion irradiation of N2O Simulated Astrophysical Ice (SAI) Relevance to the ISM and trans-neptunian Objects

Transcription

1 Ion irradiation of N2O Simulated Astrophysical Ice (SAI) Relevance to the ISM and trans-neptunian Objects Guilherme Camelier Almeida 1 Co-Workers: Cíntia P. da Costa 1, Ana Lucia F. Barros 2 and Enio Frota da Silveira 1 1 Van de Graaff Laboratory - PUC-Rio 2 Centro Federal de Educação Tecnológica (CEFET-Rio) gcalmeida@vdg.fis.puc-rio.br

2 THE SAI CULTURE Culture: The customs and beliefs, art, way of life and social organization of a particular country or group. (Oxford Dictionary) XXI Century Rush Lack of Time Padronization SAI Simulated Astrophysical Ice 2

3 Motivation: The New Horizons Mission Launched by NASA on 19 January of Runned 4,8x10 9 Km until Pluto. Met Pluto on July 14 of Collected about 64Gb of Data. It will take about 5 months plus to collect all data on Earth. Revealed that Pluto has an Atmosphere rich in N 2 with H 2 O, CH 4 and CO frozen on surface. Left Pluto on January 2016 and went further to study the KBO s

4 PLUTO DWARTH PLANET (2006) D = Km CHARON LARGEST MOON D = 1207 Km

5 Where is New Horizons Now?

6 a) S. A. Stern, et al. Science, 2015, 350, aad1815. Heart Sputnik Planum

7 S. A. Stern, et al. Science, 2015, 350, aad1815 H 2 O N 2

8 The Van de Graaff Laboratory (VDG -PUC-Rio) (1) (2) (3) (1) VDG Accelerator (2) 90 0 Magnet (3)Control Room lmw7k H +, He +, C +, N +, N 2+, O +, Ar + Beams (0.5-4 MeV )

9 VDG Experimental Station

10 Beamline FTIR Beamline UHV Chamber Overview Cryrostat Head He Cryostat Sample Deposition System Sample Rotating System Low Pressure Detector (Ion Gauge) FTIR Spectrometer ZnSe Windows Gate Valve

11 Results and Discussion

12 [b] This work. [c] Fulvio et al. (16K). [d] Lapinski et al. (10K) [12] Results and Discussion N 0 = 1 A v τ ν dv Peak Position b (cm -1 ) Peak Position c,d (cm -1 ) Peak Area Assignments Band Strength A v (x cm molecules -1 ) c 3499 d 1.91 ν 1 + ν a c 2575 d ν a 0.15 b c 2466 d 0.33 ν 1 + 2ν a c 2235 d 82.5 ν b c 1291 d 17.0 ν a 1.07 b c 1167 d 0.4 2ν a d 4.31 ν a

13 Results and Discussion Wavenumber (cm -1 ) Mode Molecule 1863 NO Monomer Stretch e,f,g NO * 1836 (A ) NO Stretch h N 2 O ON-NO Antisymetric Strech g N 2 O (B 2u ) NO Stretch i / (A) N 2 O 4 /N 2 O 5 Antisymetric NO Stretch j 1710 (B) Antisymetric NO Stretch h,j N 2 O (B 3u ) NO Strech i N 2 O Antisymetric strech k NO Antisymetric stretch k O NO 2 Antisymetric stretch L N 2 O NO 2 Symetric stretch L N 2 O Deformation of NO 2 Group L N 2 O 3 N 2 O Ice Irradiation N x O y (x = 1-2 and y = 1-5) oxides and O 3 * In ice phase, NO is arranged in (NO) 2 units which has a different structure from the dimer N 2 O 2 (Reference d). e Fateley, Bent and Crawford Jr. (1959), f Varetti and Pimentel (1971), g Krim, (1998), h Stirling et al. (1994), i Wiener and Nixon, (1957), j Hisatsune, Devlin and Wada (1962), k Shimanouchi (1977), L Nour, Chen and Laane (1983).

14 Ice Thickness Measurement N 0 = 1 A v τ ν dv L ice = N 0M ρa 104 M = g/mol ρ N2O solid = 1.16 g/cm 3 N 0 = 3.34x10 18 molecules/cm 2 L ice = 2.1 µm

15 IR Absorbance Ice Radiolysis X Ice Compaction A MeV Ion Tale Ion Fluence (10 13 ions cm -2 )

16 Destruction and Compaction Cross Sections S F = S 0 e σ df S 0 ζe σ c+ σ d F Ice Porosity ζ = (S 0 - S P )/S 0

17 Results and Discussion

18 ] ) ( 2 1 [ 2,, 0 F F N eff i d i f Formation and Destruction Cross Sections Daughter Species )] exp( ) [exp( ) (,,, 0 F F N F N d i d i d d i f i ] ) ( 2 1 [ ) ( 2,, 0 F F N F N i d d i f i If σ d F <<1, This Equation can be reduced into:

19 Low Fluence Region

20 High Fluence Region

21 PHYSICAL CHEMISTRY ASPECTS Main Dissociation 14 N + N 2 O N 2 + O (1) N 2 O 14 N + N + NO (2) O + O O 2 (3) O + O 2 O 3 (4) N + O NO (5) N + O 2 NO 2 (6) Hot Plasma Reactions N + NO 2 2NO (7) n NO 2 + O NO + O 2 (8) n n Spealman and Rodebush (1935)

22 HOW ICE CHEMISTRY OCCURS? COLDER REGIONS NO + O NO 2 (OK) (9) N 2 O + O N 2 O 2 (OK) (10) N 2 O + O 2 N 2 O 3 (OK) (11) N 2 O + O 3 N 2 O 4 (WRONG) (12) N 2 O + 2O 2 N 2 O 5 (WRONG) (13) N 2 O + O 3 + O N 2 O 5 (Very Very WRONG) (14) 2NO 2 N 2 O 4 (MORE LIKELY) (15) 2NO 2 + O N 2 O 5 (MORE LIKELY) (16) (Inner Track Reactions)

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24 Conclusions The Relative band strengths for all N 2 O FTIR Bands found were determined. The most abundant oxide produced was NO 2 followed by NO, N 2 O 3, N 2 O 2, O 3, N 2 O 4 and N 2 O 5. We were able to separate the ice compaction and the ice radiolysis effects and determine the destruction cross sections σ d and compaction cross sections σ c for all N 2 O vibration modes. The compounds produced by 14 N + ion irradiation are the same as the ones produced by 1 kev electrons (Prof. Nigel Mason s Work) o However the dynamics of production revealed to be completely different. The formation cross sections, σ f,i, as well as the destruction cross sections, σ d,i, for the compounds produced by solid N 2 O radiolysis were determined. These data may also be helpful for future astronomical investigations beyond Neptune s orbit and also for a better understanding of interstellar nitrogen chemistry. O B.Sivaraman, et al. Chem. Phys. Lett., 2008, 460,

25 You don t really know Brazil until you know Rio de Janeiro (Seu Jorge) OBRIGADO!

26 Acknowledgments : CNPq, CAPES, FAPERJ Prof. Daniele Fulvio (PUC-Rio) and Prof. Luis A. Mendes (UFBA) References a) S. A. Stern, et al. Science, 2015, 350, aad1815. b) Almeida, G.C., De Barros, A.L.F., Da Costa, C.P., Silveira, E.F. Icarus, 2016 (in revision) c) D. Fulvio, G. A. Baratta, M. E. Palumbo and N. J. Mason, Spectrochim.Acta A 2009, 72, d) A. Lapinski, J. S. Larsen, J. Waluk and J. G. Radziszewski, J. Chem. Phys., 2001, 115, e) W. G. Fateley, H. A. Bent and B. Crawford Jr., J. Chem. Phys., 1959, 31, f) E. L. Varetti and G. C. Pimentel, J. Chem. Phys., 1971, 55, g) L. Krim, J. Mol. Struct., 1998, 471, h) A. Stirling, I. Pápai, J. Mink and D. R. Salahub, J. Chem. Phys., 1994, 100, i) R. N. Wiener and E. R. Nixon, J. Chem. Phys., 1957, 26, j) I. C. Hisatsune, J. P. Devlin and Y. Wada, Spectrochim. Acta, 1962, 18, k) T. Shimanouchi, J. Phys. Chem. Ref. Data, 1977, 6, L) E. M. Nour, L. H. Chen and J. Laane, J. Phys. Chem., 1983, 87, m) C. S. Jamieson, C. J. Bennett, A. M. Mebel and R. I. Kaiser, Astrophys. J., 2005, 624, n) M. L. Spealman and W. H. Rodebush, J. Am. Chem. Soc., 1935, 57, o) B. Sivaraman, S. Ptasinska, S. Jheeta and N. Mason, Chem. Phys. Lett., 2008, 460,