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Surfaces processes IIChemical routes

François Dulieu

LERMA

Paris Observatory and Cergy Pontoise University

F- Dulieu – LERMA – Chemistry and Infrared Spectroscopy of Interstellar Dust – June 2012, Nijmegen II/III

Molecules detected in 2002 in astrophysical environments

Surface processes I

Order of magnitudesStickingDesorptionComparison of methods (TPD, RAIRS, STM)

Surface processes IIChemical routes

Surface processes IIIDiffusion on surfaceDiffusion in bulkEnergetic aspects

Studied in lab.


“Thermal cold surface Chemistry”, today

And H2O

2 ,

NH

2OH (?), CH

3NH

2 ...


H CO O2

O O3

NO C2/3

H4/6

HCN H2

H H2

H2CO

CH3OH

H2O

2

H2O

+

OH+

H2O

2

H2O

+

NH2OH

NO2

CH2NH

CH3NH

2

O OH+

CO2

(?) (O2/O

3 ) C

2/3H

4/6O

OH HCOOHH

2CO

3

CO2

HNO3

+++

H2O

“Thermal cold surface (fast) chemistry”

No bulk chemistryNo irradiation (UV, electrons, Ions...)

Review ofreactions

H+H

CO + H

Water formation

CO2 formation

HCOOH, H2CO3

C2H4O

NH2 -X

conclusion


H CO O2

O NO C2/3

H4/6

HCN H2

H H2

H2CO

CH3OH

H2O

2

H2O

OH NH2OH

NO2

CH2NH

CH3NH

2

O OH CO2

(?) (O2/O

3 ) C

2/3H

4/6O

OH HCOOHH

2CO

3

CO2

HNO3

+++

H2O

“Thermal cold surface (fast) chemistry”

Num

ber

of m

olec

ule

s

Year

Review ofreactions

H+H

CO + H

Water formation

CO2 formation

HCOOH, H2CO3

C2H4O

NH2 -X

conclusion


H2 formation, a world in itself ! (Experiments only...)

On silicatesEfficiencies & process, see numerous Vidali and coworkers, (Cazaux et al)Energetic aspects, Lemaire et al 2010

On carbonaceous materialsEfficiencies & process : Vidali et al, Menella,

Zecho et al, Hornekaer et al …Energetic aspects, S. Price and coworkers

On water Ice :Efficiencies & process : Vidali et al, Amiaud et al 2007, Hornekaer et al 2003, Watanabe et al 2010.Energetic aspects : Hornekaer et al 2003, Congiu et al 2009,

Review ofreactions

H+H

CO + H

Water formation

CO2 formation

HCOOH, H2CO3

C2H4O

NH2 -X

conclusion


CO + H

CO + H HCO

tunnelling

Pirim et al, 2010, J. Phys. Chem. A

H2CO

Review ofreactions

H+H

CO + H

Water formation

CO2 formation

HCOOH, H2CO3

C2H4O

NH2 -X

conclusion

CO H2 H

3 K

10 K


CO + H

CO + H HCOtunnelling

Pirim et al, 2010, J. Phys. Chem. A

H2CO H

2COH CH

3OH

Fuchs et al, 2009, A&A

Review ofreactions

H+H

CO + H

Water formation

CO2 formation

HCOOH, H2CO3

C2H4O

NH2 -X

conclusion


CO + HCO + H HCO

tunnellingH

2CO H

2COH CH

3OH

tunnelling

Review ofreactions

H+H

CO + H

Water formation

CO2 formation

HCOOH, H2CO3

C2H4O

NH2 -X

conclusion

Review ofreactions

H+H

CO + H

Water formation

CO2 formation

HCOOH, H2CO3

C2H4O

NH2 -X

conclusion

F- Dulieu – LERMA – Chemistry and Infrared Spectroscopy of Interstellar Dust – June 2012, Nijmegen

Oxygen and Hydrogen experimentsO beam H beam

Ozone

About 20 reactions... + different experimental conditions and methods

Review ofreactions

H+H

CO + H

Water formation

CO2 formation

HCOOH, H2CO3

C2H4O

NH2 -X

conclusion


Oxygen and Hydrogen experimentsO beam H beam

Water is easy to form experimentally !

O + H

O2 + H

O3 + H

Water is one of the compound easily formedon cold surfaces (10 - 50K)

Dulieu et al 2010, Vidali et al 2011

Miyauchi et al 2008, Ioppolo et al 2008Matar et al 2008, Oba et al 2009, Ioppolo et al 2010, Cuppen et al 2010

Mokrane et al 2009, Romanzin et al2011

Water formation rate >> CO + H ; CO+OH … > H + H

Water is amorphous and compact (Oba et al 2009, Accolla thesis)

Review ofreactions

H+H

CO + H

Water formation

CO2 formation

HCOOH, H2CO3

C2H4O

NH2 -X

conclusion


Experimental agreement ?

3 itemsNo doubt

2 itemsstrong evidences

1 itemweak evidence

No item?

See Dulieu 2011IAU 280

Review ofreactions

H+H

CO + H

Water formation

CO2 formation

HCOOH, H2CO3

C2H4O

NH2 -X

conclusion


Water formation (sub monolayer)

O2 + D → OD

O2D + D → D

2O

2

D2O

2+D → D

2O+OD

OD+ D → D2O

No barrier model. The probability of reaction is proportional to the surface concentration of reactants.

O2

HO2

H2O

2 OH

H2O

(D+D is small as longAs other product is present )

Review ofreactions

H+H

CO + H

Water formation

CO2 formation

HCOOH, H2CO3

C2H4O

NH2 -X

conclusion


O2 + D

O3+ D @ 10K

O3 + D @ 45 K

O3 +H → O2 + OHO2 desorb below 45 K

Signal O2

TPD, sub-monolayer regime


Review ofreactions

H+H

CO + H

Water formation

CO2 formation

HCOOH, H2CO3

C2H4O

NH2 -X

conclusion


O2 + D → O2DO2D + D → D2O2D2O2+D → D2O+ODOD+ D → OD

Signal H2O2

Signal H2O

Signal H2O2

OH + H ?

H2O

2 is almost always < H

2O

O3+ H @ 10K

O3 + H @ 45 K

O2 + H


Review ofreactions

H+H

CO + H

Water formation

CO2 formation

HCOOH, H2CO3

C2H4O

NH2 -X

conclusion


Water formation “Multilayer”

Ioppolo et al PCCP 2010, IR spectroscopy, growing a O

2+ H layers (35 ML)

Much more H2O

2 than H

2O

Low H2O

2 comsuption

Probably H+H → H2

is the most active reaction !

H needs to penetrate through thesample

Review ofreactions

H+H

CO + H

Water formation

CO2 formation

HCOOH, H2CO3

C2H4O

NH2 -X

conclusion


Water formation

Can explainMost of the signal,But chemical desorptionIs missing

Review ofreactions

H+H

CO + H

Water formation

CO2 formation

HCOOH, H2CO3

C2H4O

NH2 -X

conclusion


Water formation O2

HO2

H2O

2 OH

H2O

Can explainMost of the signal,But chemical desorptionIs missing

Review ofreactions

H+H

CO + H

Water formation

CO2 formation

HCOOH, H2CO3

C2H4O

NH2 -X

conclusion


Water formation

- Chemical desorption

- Substrate dependancy

Still to do :

Review ofreactions

H+H

CO + H

Water formation

CO2 formation

HCOOH, H2CO3

C2H4O

NH2 -X

conclusion


CO + OH reaction on cold surfaces

Photochemistry : CO + OH → CO2 + H

CO + OH on surfaces but “bulk or matrix” conditionsOba et al 2010, Ioppollo et al 2011, Zins et al 2011

© Noble et al 2011

No pure OH beam → in situ control of OH formation

Comparison of surfaces, coverage, temperature andChemical networks

Review ofreactions

H+H

CO + H

Water formation

CO2 formation

HCOOH, H2CO3

C2H4O

NH2 -X

conclusion


CO + OH reaction on cold surfacesH addition to CO/O2 mixtureOr CO/O3 mixture © Noble et al 2011

CO/O2 + H

Slow

HCO +HH

2CO

CO/HO2 + H

Slow

CO/H2O

2 + H

CO/OH / H2O

+ H

CO/ H2O / H

2O

CO2

+H

CO/O3 + H CO/OH + H

@ 50K

CO / H

2O

Review ofreactions

H+H

CO + H

Water formation

CO2 formation

HCOOH, H2CO3

C2H4O

NH2 -X

conclusion


CO + OH reaction on cold surfacesO2 and O3 pathways

© Noble et al 2011

CO2 is always a tiny compounds (max 4 %)No important substrate effectKinetics is different starting from O3 and O2

CO/O3 + H

CO/O2 + H

CO2

CO

Review ofreactions

H+H

CO + H

Water formation

CO2 formation

HCOOH, H2CO3

C2H4O

NH2 -X

conclusion


CO + OH reaction on cold surfacesH addition to CO/O2 mixture

© Noble et al 2011

CO2 is always a tiny compounds (max 4 %)No important substrate effectKinetics is different starting from O3 and O2

CO/O3 + H

CO/O2 + H

CO2

CO

Review ofreactions

H+H

CO + H

Water formation

CO2 formation

HCOOH, H2CO3

C2H4O

NH2 -X

conclusion


CO/O2 mixture + H (Ioppolo et al 2011) CO + OH mixture(Oba et al 2010)

From Goumans et al 2008

Review ofreactions

H+H

CO + H

Water formation

CO2 formation

HCOOH, H2CO3

C2H4O

NH2 -X

conclusion


© Congiu et al 2012, ApJ L et soumis a JCP

CO/O2 + H

- IR spectroscopy vs Mass spectroscopy

- Bulk chemistry vs surface chemistry

NH2OH synthesis via NO +H

Review ofreactions

H+H

CO + H

Water formation

CO2 formation

HCOOH, H2CO3

C2H4O

NH2 -X

conclusion



© Congiu et al 2012, ApJ

NO (et éventuellement (NO)2) exposé à H ou D à 10 K disparait

CO/O2 + H

Review ofreactions

H+H

CO + H

Water formation

CO2 formation

HCOOH, H2CO3

C2H4O

NH2 -X

conclusion


Synthèse de NH2OH via NO +H

© Congiu et al 2012, ApJ L et soumis a JCP

CO/O2 + H

Review ofreactions

H+H

CO + H

Water formation

CO2 formation

HCOOH, H2CO3

C2H4O

NH2 -X

conclusion


© Congiu et al 2012, ApJ

CO/O2 + H


Review ofreactions

H+H

CO + H

Water formation

CO2 formation

HCOOH, H2CO3

C2H4O

NH2 -X

conclusion


© Congiu et al 2012, ApJ L and submitted to JCP© Fedoroseev et al 2012, submitted to JCP

- IR spectroscopy vs Mass spectroscopy

- Bulk chemistry vs surface chemistry

- "Fast” chemistry vs “slow” chemistry

Review ofreactions

H+H

CO + H

Water formation

CO2 formation

HCOOH, H2CO3

C2H4O

NH2 -X

conclusion


HCN + H

© Theulé et al 2011, A&A

Review ofreactions

H+H

CO + H

Water formation

CO2 formation

HCOOH, H2CO3

C2H4O

NH2 -X

conclusion


C2H4 + O → C2H4O

© Ward & Price 2011, ApJ

Review ofreactions

H+H

CO + H

Water formation

CO2 formation

HCOOH, H2CO3

C2H4O

NH2 -X

conclusion


C2H4 + O → C2H4O

© Ward & Price 2011, ApJ

==

Review ofreactions

H+H

CO + H

Water formation

CO2 formation

HCOOH, H2CO3

C2H4O

NH2 -X

conclusion


“Fast and slow chemistry”Surface and bulk chemistry

© Mispealer, 2012, A&A

Review ofreactions

H+H

CO + H

Water formation

CO2 formation

HCOOH, H2CO3

C2H4O

NH2 -X

conclusion


Surface, dynamic matrix and bulk chemistry

More and more molecules …

Be carrefull when you compare results.

Surface: competition of fast process - stable products and fast reactions

Matrix dynamically grown : - radicals may survive- “secondary” reactions can happen- can be surface reactions if the reaction are faster than the growth

(T dependant)

Bulk chemistry- driven by slow reorganisation of the ice- in competition with desorption

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