Chemical analysis of surfaces and organic thin films
by means of SIMS
Secondary ion mass spectrometry (SIMS)
– Static SIMS (SSIMS) vs. dynamic SIMS –
Cu (111) surface 1 ps after the
bombardment with a Cu atom having
an energy of 5 keV.
(H.M. Urbassek: Molecular-dynamic
simulation of sputtering. Nuclear Instru-
ments and methods in Physics Research,
VOL B 122 (1997), S. 427-441)
1 2 3 4 6 8 10
10
10
10
10
10
10-1
-2
-3
-4
-5
-6
rel. yield
culster size (Ag)
experiment
n
Monte Carlo
moleculardynamis (500 ps)
moleculardynamic(nascent)
X+ + -
surface
ion gun
beam of primary ions
of the sample
desorbed neutral particle
desorbed anion
desorbed cation
shock wave
X+ + -
ion gun
desorbed
desorbed anion
desorbed cation
shock wave
SNMS
SIMS
SIMS
mass analyzer m/z
neutral particle
Quadruple secondary ion mass spectrometer
detector
alternating voltage
Sector field secondary ion mass spectrometer
detektorH
Secondary ion mass spectrometry (SIMS)
– Units to separate (molecule) ions of different masses –
Sector field secondary ion mass spectrometer
– NanoSIMS 50 (Cameca, Paris, France) –
Si- BSi-
silicon doped with boron,
line width 0,14 µm,
acquisition time: 16 min (ONERA, France)
sample
extractor
tube
+
reflector
detector
Ar ions
pulsed
22
kin t
s
2
mv
2m
E
+--
Ar+
U = 10 kV Ekin
+-0
+
J.C. Vickerman
Charles Evans
A. Benninghoven
Static secondary ion mass spectrometry (SSIMS)
– Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) –
Time-of-Flight Seconday Ion Mass Spectrometry (ToF-SIMS)
– Pulsed primary ion beam –
x/y deflector
lense
extraction unit
anode
gas inlet
ion source
90° deflector
focus
sample
lense
buncher deflector
buncher
puls length 59...1888 ps
sample deflector
2 2
kin t
s
2
m v
2 m
E
20 40 100 140 160 180 200
m/z [amu] 50 100 150 200
count rate
C 2 H 2 + SiO
+
C +
polystyrene fingerprint spectrum
C 2 H 3 +
C H 3 +
C H 2 +
C H 3 +
Si , + C 2 H 4
+
C 2 H 5 +
C 3 H 3 +
,
C 3 H 5 +
C 3 H 7 +
C 4 H 5 +
C 4 H 7 +
C 4 H 9 +
C 5 H 5 +
C 6 H 5 +
C 7 H 7 +
C 8 H 9 +
C 9 H 7 +
C H C H 2
Time-of-Flight Seconday Ion Mass Spectrometry (ToF-SIMS)
– Spectral information –
Time-of-Flight Seconday Ion Mass Spectrometry (ToF-SIMS)
– Excellent mass resolution – PTFE after its treatment in a hydrogen plasma –
69.0 81.0 119.0 .5 .6 .6
CF 3 + C 2 F 5
+ C 2 F 3 +
C 6 H 9 +
unmodified PTFE
69.0 81.0 119.0 .6 .6 .5 m/z [amu]
C 5 H 9 +
C 6 F 2 H 2 +
CF 3 + C 2 F 3
+ C 2 F 5 + C 6 H 9
+
C 5 H 7 N +
F
F
H H
H +
plasma-treated PTFE
m/z measured mm calculated mc = |mm-mc|
CF3+ 68.9873 68.9952 0.0079
C5H9+ 69.0695 69.0717 0.0022
C2F3+ 80.9888 80.9952 0.0064
C6H9+ 81.0645 81.0717 0.0072
C2F5+ 118.9858 118.9920 0.0062
C6H9F2+ 119.0659 119.0685 0.0026
All values were given in [amu]
Fragmentation mechanisms
– e.g. Polymers with aromatic units –
CH2 CH CH3
C CH2
103 amu
- H- H
- ethylene 27 amu
77 amu
39 amu
- ethylene
51 amu
- propylene (41 amu)
CH2 CH CH3
CH2 CH CH2
77 amu- phen- H
51 amu
39 amu- H2
128 amu
152 amu
178 amu
m/z [amu]60 80 100 120
Polystyren auf SilberAg107
Ag109 HC CH2
Cl
m/z [amu]500 700 900 1100
x 13
m = 14,014 amu (CH
HC CH2
+
Poly(4-chlorstyren)
-
2)
Fragmentation mechanisms
– e.g. Polymers with aromatic units –
Polystyrene on silver substrate
Poly(4-chloro styrene)
Analysis of additives in polymers
– No chance for XPS –
600 640 68060 180100 140 220 260 300
277233
m/z [amu]
637
HO
H3C
CH2 CH2 C
O
CH2CH2O CH2CH2 O C
O
CH2CH2 OH
CH3
O
Irganox 245
600 640 68060 180100 140 220
235
191
m/z [amu]
HO CH2 CH2 C
O
O CH2(CH2)4CH2 O C
O
CH2CH2 OH
Irganox 259
595
[M–H]-
[M–H]-
Analysis of additives, impurities, modifiers etc.
Application note of ToF-SIMS
– Grafting of styrene and maleic anhydride on polyolefin surfaces –
There are polystyrene sequences
[Sty-Sty-Sty] ?
There are maleic anhydride sequences
[MSA-MSA-MSA] ?
There are hydrolyzed maleic anhydride
groups?
C H 2 C H
O O O
H H C H 2 C H
+ monomers, + initiator
m/z [amu]160 180 200
147
152
161
165
203
205178
207
215
217233
150 170 190 210 220
152
165
178
205 C CH CH2C
207 C CH CH3CH
147 H2C CH2 CH2
C
O+
161 H2C CH2 CH2 CH2
C
O+
203 HC CH2
OO
CH2
CO
C
CH
215 HC C CH2 CH
CO
C
CH2
O O
217 CH CH2 CH
CO
C
CH2
O O
H2C
233 HC C CH2 CH CH2
C CO O
OH OH
20 m/z [amu]40 60 80
x 200 200 µm
15.02 amu 22.99 amu 29.04 amu 38.97 amu 62.94 amu 77.04 amu
281.08 amu197.00 amu91.06 amu
low count rate high count rate
50 µm
Imaging-ToF-SIMS
– Laterally structured poly(-benzyl glutamate) –
20 m/z [amu]40 60 80
x 200 200 µm
15.99 amu 26.02 amu 31.97 amu 32.98 amu 89.08 amu 89.12 amu
163.12 amu 196.96 amu 213.03 amu 394.01 amu 394.08 amu
Total ion image and linescan high count rate
Imaging-ToF-SIMS
– Laterally structured poly(-benzyl glutamate) –
Summary
SSIMS [ToF-SIMS]
SSIMS is a method oriented to detect and analyse molecules on the surface of samples
analysis of molecule species [chemical structure and mass of the polymer's repeating units
type of monomer
non-quantitative surface analysis [semi-quantitative surface analysis],
analysis of end groups Endgruppen determination of molar masses and molar mass
distributions on surfaces
analysis of additives, impurities, modifiers etc. [traces can be detected],
analysis of structural changes caused by surface mofication, functionalization, and aging.