Fo ma ion o OCS
in in e s ella ices
Ra ael Ma ín-Doménech, Ka in I. Öbe g, Guille mo M. Muñoz Ca o, Héc o
Ca ascosa, Asunción Fuen e, Mahesh Rajappan
10/03/25
TOWARDS NEW FRONTIERS | 10-14 MARCH 2025 | ESO GARCHING
1.- In oduc ion S chemis y in he dense ISM
Laas & Caselli 2019Calmon e e al. 2016McClu e e al. 2023
Rela i e abundances o S-bea ing molecules in ice man les
S/H
C edi s: A. Fuen e
S locked
in ices?
Ice obse a ions wi h JWST
•Melissa McClu e
•Zak Smi h
•Angèle Tailla d (de ec abili y o S-bea ing)
•Ka e ina Sla icinska (de ec ion o NH4SH)
2/17
H2O:CS2 3:1
CO:CS2 7:1
CO2:CS2 7:1
2.- Labo a o y Expe imen s Me hodology
1
3
4
13 2
6
9
810 12
12
5
11
14
1 UHV chambe
2 Tu bomolecula pump
3 C yos a
4 Gas line
5 Gas dose
6 Elec on gun
7a/7b Nd:YAG lase s
8 Dye lase
9 OPO
10 VUV cell
11 VUV guiding a m
12 FTIR spec ome e
13 QMS
14 Re-ToF MS (hinde ed)
7a
7b
Maksyu enko e al. 2022
The SPACE TIGER se up a he C A
3/17
H218O:CS2 3:1
13C18O:CS2 7:1
13C18O2:CS2 7:1
Labo a o y expe imen s unde as ophysically ele an condi ions
2.- Labo a o y Expe imen s Me hodology
UHV chambe
(base p essu e in he 10-10 o ange)
ELG-2/EGPS-1022 low ene gy
elec on sou ce.
I adia ion equi alen o CR
du ing ~5x106 yea s
Subs a e can be cooled down o 7 K
4/17
FTIR spec ome e
2.- Me hodology Moni o ing he ice
Labo a o y expe imen s unde as ophysically ele an condi ions
5/17
2.- Me hodology Moni o ing he gas
Quad upole Mass Spec ome e
(QMS)
•The mal deso p ion → Tempe a u e
P og ammed Deso p ion (TPD)
Tempe a u e
m/z = 44 signal
Labo a o y expe imen s unde as ophysically ele an condi ions
6/17
3.- Resul s H218O : CS2 + e- i adia ion
S chemis y
Ma ín-Doménech e al. 2024
7/17
3.- Resul s H218O : CS2 + e- i adia ion
S chemis y
Ma ín-Doménech e al. 2024
8/17
3.- Resul s H218O : CS2 + e- i adia ion
S chemis y
Ma ín-Doménech e al. 2024
9/17
4.- Conclusions
•Dissocia ion o CS2 molecules upon ene ge ic p ocessing leads o he
o ma ion o se e al de ec able S-bea ing p oduc s: OCS, SO2, C3S2,
S2.
•Sul u chemis y in CS2-bea ing ices could be domina ed by he
o ma ion o unde ec able long sul u chains.
•Fo ma ion o OCS h ough he CS+O → OCS pa hway seems o be
mo e e icien han CO+S → OCS unde he same condi ions.
CS+O could play a ole especially in wa m egions wi h no CO ice.
16/17
LSAIP
Guille mo M. Muñoz Ca o
Héc o Ca ascosa de Lucas
B uno Esc ibano
Ca los del Bu go Oli a es
SUL4LIFE
Asunción Fuen e
Angèle Tailla d
Da id Na a o Almaida
Öbe g As ochemis y G oup
Ka in I. Öbe g
Mahesh Rajappan
Ele a Piacen ino
Suchi a Na ayanan
Alexia Simon
Ma issa Maney
LCF/BQ/PI22/11910030
Danke schön!
1.- In oduc ion OCS - expe imen s
➢In gene al, wo OCS ice o ma ion pa hways ha e been p oposed in he li e a u e
CS + O → OCS
CO + S → OCS
➢Bo h pa hways ha e been es ed in he labo a o y
•CS2 + O a 15-70 K (Wa d e al. 2012)
•e- i adia ion o CS2:O2 a 12 K (Mai y & Kaise 2013)
•H+ i adia ion o CO:H2S, CO2:H2S, CO:SO2, CO2:SO2 a 10 K (Fe an e e al. 2008)
•H+ i adia ion o CO:H2S, CO:SO2 a 16-20 K (Ga ozzo e al. 2010)
•UV i adia ion o CO:H2S, CO2:H2S a 14 K (Chen e al. 2015)
OCS o ma ion pa hways
CO sou ce (CO o CO2) + S sou ce (H2S o SO2) + i adia ion
CS sou ce (CS2) + O sou ce (O o O2) + i adia ion
CO+S p e e ed, bu con ibu ion depends on he a ailabili y o eac an s AND ela i e eac ion a es
1.- In oduc ion Models
➢In gene al, wo OCS ice o ma ion pa hways ha e been p oposed in he li e a u e
CS + O → OCS
CO + S → OCS
OCS o ma ion pa hways
THIS WORK: CO:CS2 and CO2:CS2 + e- i adia ion a 7-50 K
1. Compa e he ela i e e iciencies o bo h pa hways unde he same
condi ions (CO, CS, O, S p esen ) and s udy he e ec o i adia ion
empe a u e
2. Explo e he chemis y o CS2 molecules in ealis ic ice en i onmen s (also
H2O ice ma ix)
➢De ec ed in come s
➢P edic ed in ice models (Laas & Caselli 2019)
➢De ec ed as one o he p oduc s upon ene ge ic p ocessing o CO:H2S and CO:SO2 ice mix u es
➢P oposed pa en molecule o he de ec ed CS in he gas phase
Appendix CS2:O2 + e- i adia ion
Mai y & Kaise 2013
CS2:O2 + e- i adia ion
Appendix Repo ed expe imen s
Ma ín-Doménech e al. 2024
Appendix Mass balance
Column densi ies (x 1E15
molecules/cm2)
Expe imen 1 Expe imen 2
Species Ini ial Final Ini ial Final
13C18O2
182 135 172 124
CS2 24 10 31 12
13C18O
057 058
C18O 012 013
C18O2 0 1.1 0 1.3
S18O2 0 8 0 9
S18O3 0 1.1 0 1.3
18O13CS
0 0.3 0 0.3
18OCS 0 1.2 0 1.2
C3S2 0 0.4 0 0.4
S2 0 0.7 0 0.8
To al S-
bea ing
24 21
To al
Sul u 48 33
Appendix 13C18O2 : CS2 + e- i adia ion
Ma ín-Doménech e al. 2024
Appendix 13C18O2 : CS2 + e- i adia ion
18O13CS IR assignmen
Ma ín-Doménech e al. 2024
Appendix 13C18O2 : CS2 + e- i adia ion
TPD cu es o p oduc s o he han OCS a 7 K
Ma ín-Doménech e al. 2024
Appendix 13C18O2 : CS2 + VUV pho on i adia ion
IR e olu ion du ing TPD o he ice sample i adia ed a 10 K
Addi ional con ibu ion o he IR band (p obably 13C18O3) ha disappea s a 80 K
%18OCS (CS+O) a he end o he expe imen = 78%
Ma ín-Doménech e al. 2024
3.- Resul s 13C18O : CS2 + e- i adia ion
CS2CS S
13C18O
18O
13C
18O13CS
18OCS
+
+
This pa hway is a o ed!!...
Bu we can s ill s udy he S
chemis y and he e olu ion
o OCS o ma ion wi h T
OCS o ma ion pa hways
Appendix 13C18O : CS2 + e- i adia ion
Ma ín-Doménech e al. 2024
Appendix 13C18O : CS2 + e- i adia ion
OCS o ma ion pa hways a 7-25 K
Ma ín-Doménech e al. 2024
Appendix 13C18O : CS2 + e- i adia ion
OCS o ma ion pa hways a 7-25 K
7 K 15 K 25 K
Ma ín-Doménech e al. 2024
Appendix 13C18O : CS2 + e- i adia ion
TPD cu es o p oduc s o he han OCS a 7 K
Ma ín-Doménech e al. 2024
Appendix 13C18O : CS2 + e- i adia ion
Ma ín-Doménech e al. 2024
Appendix 13C18O : CS2 + e- i adia ion
De ec ion o C2S
Appendix H2O:CS2 / H218O:CS2 + e- i adia ion
3.- Resul s H218O : CS2 + e- i adia ion
CS2CS
H218O
18OH.
H
18OCS
+
+
S
