kev e - and H + ECR source Shock wave Molecular ices 3 C 2 H 2 C 6 H 6 2 C 3 H 3 Dust impact Europa

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1 B Sivaraman

2 kev e - and H + Shock wave Molecular ices ECR source 3 C 2 H 2 C 6 H 6 Europa Dust impact 2 C 3 H 3 C 6 H 6

3 Temperature, K 273 K 70 / K K < 20 K

4 New molecules (ISM) C 60 - C H 30 2 O Time (year)

5 Icy satellites Chemistry / Physics? Europa Ganymede Callisto Rhea Dione

6 Exclusive Satellites

7 Magnetospheres Complex, dynamic chemistry labs that mix the species flowing through them in turbulent, mathematically complicated ways. They act as (Delitsky and Lane, JGR, 2002).

8 Satellites in Magnetosphere (Delitsky and Lane, JGR, 2002).

9 Solid Gas

10 Reactions Generation - 0 Generation - 1 Generation - 2 Sivaraman et al, Chem Phys Lett, 2014

11 Ice Chemistry H/H 2 < 1 H/H 2 > 1 Bare grain chemistry e.g. H 2 formation

12 Irradiation & Implantation KINETIC ENERGY, ev Inelastic Interactions, Ionization, Excitation Elastic Chemical Epitherm Interactions, Inter Region, Displacements, actions Excited Replacements Species Thermal Reactions, Diffusion

13 Simulating Space 10-3 mbar Pressure in a light bulb 10-6 mbar Pressure in a TV tube mbar The average pressure on the surface of Mars 10-5 mbar Pressure in the upper atmosphere - 27 ºC The lowest temperature recorded in the UK - 89 ºC The lowest temperature recorded on Earth ºC The boiling point of water 38 ºC The highest temperature recorded in the UK 0 ºC Freezing point of water - 60 ºC The average temperature on the surface of Mars mbar Pressure in an ultra high vacuum chamber ºC The boiling point of liquid nitrogen mbar Pressure in interstellar space ºC Temperature in interstellar space ºC Absolute zero

14 Spectroscopy - Probing molecules in the ice phase

15 Open Cyclic (??)

16 What happened to C 6 H 6 (or even C 3 H 3 )? in CH4 (Neon Matrix) [(C 13 )?? ] [C 2 H 2 and C 4 H 4 was observed!!] Lin et al., J Phys Chem A, 2014

17 PAH from simple units!!

18 Benzene dissociation

19 Ion Irradiated Frozen Benzene (Strazulla et al, A&A, 1991)

20 Benzene, H + and UV Irradiation (Ruiterkamp et al, A&A, 2005) MIS HC 2 CH 3 - methylacetylene (only in Matrix isolation) Lots of C 2 H 2 and clusters of C 2 H 2

21 Benzene dissociation in UV (gas phase) Boechat-Roberty H M et al. MNRAS 2009

22 NUMBER OF MOLECULES COMETARY MOLECULES Vs YEAR C 3 H YEAR Probable detection of organic dust borne aromatic C 3 H Korth et al, Nature, 1989.

23 Benzene synthesis

24 Benzene formation from Acetylene (C 2 H 2 ) Zhou et al 2010

25 First proposal (Interstellar Combustion chemistry) (Cherchneff, et al. 1992) C 3 H 3 was proposed to play a key role in C 6 H 6 formation in the ISM.

26 Hunt for propargyl radical Experimental plan

27 Propargyl alcohol (C 3 H 3 OH) Propargyl Alcohol Propenal CH 2 CHCHO Propenal in ISM Dickens et al, Spec Chim Acta, Confirmed by, Hollis et al, ApJ, 2004.

28 Absorbance The propargyl alcohol (C 3 H 3 OH) Wavenumber (cm -1 ) Accepted in ApJ, Sivaraman et al (2014)

29 Observed peak positions of amorphous and crystalline propargyl alcohol. 85 K 180 K (Amorphous) (Crystalline) Assignment dimer band CH stretch CH 2 sym stretch (Fermi resonance) CH 2 bending overtone (Fermi resonance) combination band CO stretch overtone * CH 2 bending * CH 2 wagging CH stretch overtone CO stretch CH 2 scissoring CC stretch * CH bending * CH (out of plane) bending CCO bending based on Nyquist 1971 * also assigned to dimer band Accepted in ApJ, Sivaraman et al (2014)

30 Hunt for PAH First ring closure Accepted in ApJ, Sivaraman et al (2014)

31 Propargyl radical (C 3 H 3 ) signature Annealed after irradiation (180 K) At the end of irradiation (2 kev) Amorphous propargyl alcohol (85 K)

32 c-benzene (C 6 H 6 ) Accepted in ApJ, Sivaraman et al (2014)

33 C 3 H 3 C 6 H 6 Aromatic Complex Aromatic Infrared Band (AIB)

34 AIB Aromatic Infrared Band Observed in the Spitzer Infrared Spectra Residues Soot formation

35 Spitzer spectra Synthesizing C 60 in ISM NGC 4371 region (unpublished)

36 Residues Soot formation! Soot formation Dust particles Dust particles collision Dust - Dust collision Dust - Ice collision

37 Proposed (1992) and Experimentally proved (2014)