D . F anciele K uczkiewicz
How chemical complexi y lou ishes on dus g ains:
CH3SH o ma ion on cold molecula clouds
Towa ds New F on ie s
10 – 14 Ma ch, ESO Ga ching
Ma ie Cu ie Skłodowska Ac ions (MSCA) Indi idual Fellow
Labo a o y o As ophysics (L A), Leiden Uni e si y
The Ne he lands
How do molecules o m in as ophysical
en i onmen s, and wha can hey ell us abou
he physical and chemical condi ions o he
egions whe e hey a e de ec ed?
Sul u -bea ing species:
Simple: H2S, OCS, H2CS, CS₂, SO₂, S₈, NH₄SH
Complex: CH3SH,CH3CH2SH, CH2CHSH, HSCH2CH2SH
How do molecules o m in as ophysical
en i onmen s, and wha can hey ell us abou
he physical and chemical condi ions o he
egions whe e hey a e de ec ed?
Sul u chemis y … and how di e en wo ks his week add ess i
S-deple ion p oblem
Angèle Tailla d
Julia San os
Ka e ina Sla icinska
di use clouds
[S]
[H]
≈
10-5
S d a io ~ S d a io
1% s d. 10% s d.
Sola Sys em
p o oplane a y disk
dense clouds
Sul u chemis y … and how di e en wo ks his week add ess i
S-deple ion p oblem S solid-s a e chemis y
Angèle Tailla d
Julia San os
Ka e ina Sla icinska
Ra ael Ma in Domenech
Julia San os
Ka e ina Sla icinska
di use clouds
[S]
[H]
≈
10-5
S d a io ~ S d a io
1% s d.
S+gas ⟶ S-p ecu so ice
ene ge ic p ocessing (UV/CRs)
non-ene ge ic p ocessing
(a oms/ adicals)
⟶⟶
S-bea ing-p oduc
10% s d.
Sola Sys em
p o oplane a y disk
dense clouds
Sul u chemis y … and how di e en wo ks his week add ess i
S-deple ion p oblem S solid-s a e chemis y S-bea ing species
as a ace
Angèle Tailla d
Julia San os
Ka e ina Sla icinska
Ma ia Te esa Valdi ia Mena
Lau a Colzi
Ra ael Ma in Domenech
Julia San os
Ka e ina Sla icinska
di use clouds
[S]
[H]
≈
10-5
S d a io ~ S d a io
1% s d.
Tychoenic+21
S+gas ⟶ S-p ecu so ice
ene ge ic p ocessing (UV/CRs)
non-ene ge ic p ocessing
(a oms/ adicals)
⟶⟶
S-bea ing-p oduc
+Pos e s: Miguel Sanz-No o, Lau a Schölle
10% s d.
Sola Sys em
p o oplane a y disk
dense clouds
S-deple ion p oblem S-bea ing species
as a ace
di use clouds
[S]
[H]
≈
10-5
S d a io ~ S d a io
1% s d.
Tychoenic+21
10% s d.
Sola Sys em
p o oplane a y disk
dense clouds
Sul u chemis y … and how di e en wo ks his week add ess i
S solid-s a e chemis y
S+gas ⟶ S-p ecu so ice
ene ge ic p ocessing (UV/CRs)
non-ene ge ic p ocessing
(a oms/ adicals)
⟶⟶
S-bea ing-p oduc
a.k.a
Me h yl
Me ca p a n
H2S + H2/H/C ⟶ CH3SH
his wo k
CH3SH: he a ge molecule
•Fi s CH3SH de ec ion:
•Sg B2 Tu ne 1977; Linke+1979
•Fi s CH2DSH de ec ion:
•IRAS 16293-2422 Bunn+2025
CH3OH
Me h anol
Wa anabe+02; Fuchs+09; Chuang+16, 17;
Fedosee +17; San os+22
CO ⟶ HCO ⟶ H2CO ⟶ CH3O ⟶ CH3OH
+H +H +H +H
CH3SH
Me h yl Me cap an
CS ⟶ HCS ⟶ H2CS ⟶ CH3S ⟶ CH3SH
+H +H +H +H
Lambe s+18
CH3SH is he
S-analogue o CH3OH
CH3SH: he a ge molecule
•Fi s CH3SH de ec ion:
•Sg B2 Tu ne 1977; Linke+1979
•Fi s CH2DSH de ec ion:
•IRAS 16293-2422 Bunn+2025
CH3OH
Me h anol
Wa anabe+02; Fuchs+09; Chuang+16, 17;
Fedosee +17; San os+22
CO ⟶ HCO ⟶ H2CO ⟶ CH3O ⟶ CH3OH
+H +H +H +H
CH3SH
Me h yl Me cap an
CS ⟶ HCS ⟶ H2CS ⟶ CH3S ⟶ CH3SH
+H +H +H +H
Lambe s+18
CH3SH is he
S-analogue o CH3OH
Beyond CS hyd ogena ion:
Wha al e na i e pa hways lead o
CH₃SH o ma ion, and wha do hey
e eal abou sul u chemis y in s a -
o ming en i onmen s?
C + H + H2S: TPD
H2CS and CH3SH deso b a di e en empe a u es wi h dis inc
agmen a ion pa e ns
-CH3SH
- IR spec a and agmen s ma ch wi h NIST da abase
- H2CS:
- C + H2S
- Tdes highe han expec ed, migh be o ming a ime o
bigge oligome s
1400 1200 1000
0.000
0.002
0.004
H2S
Abso bance
Wa enumbe (cm-1)
C + H2S + H(H2)
C + H2S + H2
C + H2S+( ace H2)
C + H2S @35 K
CH4
CH3SH CH3SH CH3SH
CH3SH
H2CS H2CS
H2CS
Less H2
Mo e H2
C + H/H2 + H2S: IR SPECTRA
H2CS and CH3SH o ma ion in a ious H/H2 condi ions
1400 1200 1000
0.000
0.002
0.004
H2S
Abso bance
Wa enumbe (cm-1)
C + H2S + H(H2)
C + H2S + H2
C + H2S+( ace H2)
C + H2S @35 K
CH4
CH3SH CH3SH CH3SH
CH3SH
H2CS H2CS
H2CS
Less H2
Mo e H2
C + H/H2 + H2S: IR SPECTRA
H2CS and CH3SH o ma ion in a ious H/H2 condi ions
Less H/H2Mo e H/H2
0.0
0.2
0.4
0.6
0.8
1.0
C + H2S + H/H2
C + H2S + H2
C + H2S + ( ance H2)
No malized abundance*
Expe imen
CH3SH
H2CS
*No malized o he N(H2CS) o C+H2S@35 K
C + H2S (@35K)
C + H/H2 + H2S
H2CS and CH3SH o ma ion wi h di e en e iciencies
he absence o wi h e y
low H/H₂, H₂CS domina es o ma ion o CH₃SH
p edomina es
C + H2S ⟶ H2CS C ⟶ CH2
CH2 ⟶ CH3SH
C ⟶ CH2 ⟶ CH4
+H2
Con ibu es o CH4 o ma ion
Lambe s+2022
+H2
+H2
+H2S
Less H/H2Mo e H/H2
0.0
0.2
0.4
0.6
0.8
1.0
C + H2S + H/H2
C + H2S + H2
C + H2S + ( ance H2)
No malized abundance*
Expe imen
CH3SH
H2CS
*No malized o he N(H2CS) o C+H2S@35 K
C + H2S (@35K)
C + H/H2 + H2S
H2CS and CH3SH o ma ion wi h di e en e iciencies
he absence o wi h e y
low H/H₂, H₂CS domina es o ma ion o CH₃SH
p edomina es
C + H2S ⟶ H2CS C ⟶ CH2
CH2 ⟶ CH3SH
C ⟶ CH2 ⟶ CH4
+H2
Con ibu es o CH4 o ma ion
Lambe s+2022
+H2
+H2
+H2S
Beyond CS
hyd ogena ion
P es ella co e chemis y
…and whe e C + H2S + H2 is ele an
Snow & McCall, 2006
an Dishoeck & Black (1989)
H2S(s) + H2 (g) + C(g)
Whe e
is a ailable
simul aneously?
H₂ is 2 - 4 x mo e
abundan han H!
P es ella co e chemis y
…and whe e C + H2S + H2 is ele an
Ru le+99
A low abundances CO can
be des oyed by He+
and C a oms a e a ailable
a dense egions
chemical model o a collapsing cloud
P es ella co e chemis y
Inc easing densi y, dec easing empe a u e
H2 ⟶ H2+ ⟶ H3+
c H2
Cen al in gas-phase eac ions
H3+ + HD ⟶ H2D+ + H2 + 230 K
Wa son+1974
Cecca elli+PPVI 2014
H2S(s) + H2/H/C(g)
Sil ia Spezzano
Paola Caselli
H2/HD
emains
cons an !
Lab As o mee ing
Ringbe g Cas le, Oc 24
Sil ia Spezzano
Paola Caselli
H2/HD
emains
cons an !
c
c
So solid-s a e
eac ions wi h H2/HD
wouldn’ a ec
D- ac iona ion!
F anciele
K uczkiewicz
Lab As o mee ing
Ringbe g Cas le, Oc 24
Which mechanisms and
ba ie s a e in o play? C + H2 + H2S
2) “H-assis ed” mechanism
e.g. Molpece e+21,
Fe e o+23
C + H2O → H2CO
p oceeds ba ie less due o a ca aly ic e ec
p o ided by he H-bonded ne wo ks om
wa e
Molpece es+21
Molpece es+21
