1. Bok Globule Barnard 68

2. Interstellar grains
Sub-micron sizes

3. Interstellar grains
Sub-micron sizes
Cabonaceous and silicate material et ????

4. Interstellar grains
Sub-micron sizes
Cabonaceous and silicate material et ????
Who knows?

5. Gr  H…Gr  H…Gr…H  Gr…H2  H2  + Gr
Charge transfer
Exchange reaction 1
Exchange reaction 2
Exchange reaction 3

6. Gr  H…Gr  H…Gr…H  Gr…H2  H2  + Gr
Charge transfer
Exchange reaction 1
Exchange reaction 2
Exchange reaction 3

7. Gr  H…Gr  H…Gr…H  Gr…H2  H2  O+  O + Gr
H H h
Gr  H…Gr  H…Gr…H  Gr…H2  H2  O+  O Gr
Charge transfer
Exchange reaction 1
Exchange reaction 2
Exchange reaction 3

8. Gr  H…Gr  H…Gr…H  Gr…H2  H2 + Gr
H H h
Gr  H…Gr  H…Gr…H  Gr…H2  H Gr
Charge transfer
Exchange reaction 1
Exchange reaction 2
Exchange reaction 3

10. h photon or energy of reaction
Localised heating

11. Critical Temperature Tc for lift-off for various molecules adsorbed on grains by van der Waals interactions
Tc(K)
H < 3
N2 13
CO 14
CH4 19
NH3 60
H2O 92

14. Harry Kroto 2004

15. Photo dissociation tPD = 103 AB + h  A + B
Lifetimes (in yrs)
Photo dissociation tPD = AB + h  A + B
2-body collisions t2B = 103/n A + B  AB*  A + B
Radiative association tRA = 109/n yrs A + B  AB*  AB + h
Grain catalysis tGC = 109/n yrs A + B + Gr  AB + Gr
3 - body collision t3B = 1023/ n A + B + M  MAB  AB + M
t(BIG U) = 1010 yrs
n number of atoms or molecules per cm3
Harry Kroto 2004

16. Harry Kroto 2004

17. Harry Kroto 2004

18. Harry Kroto 2004