Thermal desorption study of selected austenitic stainless steel:

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Thermal desorption study of selected austenitic
stainless steel Bache, J.-P., J.Vacuum Science
and Technology A21, 167(2003).
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Thermal desorption study of selected austenitic
stainless steel Bache, J.-P., J.Vacuum Science
and Technology A21, 167(2003).
ARCMelted in electric arc furnace
MC(N) precipitates
AODArc-oxygen decarburation
ESRElectro slag remelting
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Precipitates
MC TiC/TiC M(CN) Nb(CN)/Ti(CN)/AlN M23C6
Cr16Fe5Mo2)C6(FeCr)23C6(Cr17Fe4-5)C6 M6C
(CrCoMoNi)6(TiNi)6C(Fe3Mo3)C Austenitic
Stainless Steels, Microstructure and Mechanical
Properties P.Marshall (Elsevier Applied Science,
1984),pp.32.
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Surface desorption bulk
outgassing Non-uniformity (poly crystalline,
interfaces, precipitates
Temperature uniformity is most important
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TDS?????
316 Ti ARCAOD
316LN ESR
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?H2???
950? 2h heating Complete outgassing

TDS after charging H2
No vented 480? peak Air vented 680 and 800?
peaks
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Comments on TDS measurement

• Surface composition change monitored by XPS
• 110? oxide and hydroxide of Cr and Fe H2O
• 270? reduction of iron oxide, decrease of H2O
  and C
• 570? increase of Cr hydroxide, Segregation of Mn
  and Si
• 870? complete reduction of oxide, metallic
  surface
• Origin of desorption peak
• 480? peak diffusible interstitial H. Ed0.52eV
• 600-800? reduction of Fe or Cr oxide
• Cracks in the thick oxide layer causes sharp peak
  above 600? in case of air bake process
• 500-600? peak for 316 Ti Hydrogen trapped at
  precipitates

Hydrogen charging without air vent
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Electron Stimulated Desorption (ESD)
Y.Ishikawa, Rev.Phys.Chem.Japan 16,83, 117 (1942).

1. M.L.Knotek Rep. Prog. Phys. 47,1499(1984).
2. M.L.Knotek Physics Today September, 24 (1984).
3. R.D.Ramsier, T.T.Yates Surface Science Report
   12, 246(1991).
4. Desorption induced by electron transition (DIET)
   1Springer series in chemical physics, 24,1(1983).

Ta getter
FE tube
W surface
filament
tip
doser
e-gun
Menzel, Gomer J Chem Phys 41(1964)3311.
RedheadCan.J.Phys. 42(1964)886.
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Arakawa-Tuzi
(C.Oshima)
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??????Electron stimulated desorption
(ESD)Desorption induced by electronic
transition(DIET)
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Menzel-Gomer-Redhead model (MGR)
?neutral
M.L.KnotekRep.Prog.Phys. 47(1984)1499.
?Franck-Condon excitation to antibonding state
Escape probability
vvelocity
Srslope
??????
For H/W(001), D/W(001)
Franck-Condon
Quantum mechanical formulation
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Threshold energy
N2
Thershold energy 5eV for N2 10eV for CO
CO
CO
Knotek?Fig.8.
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Knotek-Feibelman model for ionic surfaces
Maximal valency ionic compound
K2O,CaO,ScO3,V2O5 Maximal valency Cation is
ionized to electron configuration of rare gas atom
Ti 4 in TiO2
O desorption
Core-hole
Sub-maximal valency
Maximal valency
3 electrons of O2- released
No O desorption
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Antoniewicz model for physisorbed molecules
P.R.Antoniewicz, Phys.Rev. B21, 3811(1980).
????
?positive ion formation ? attraction by image
force
Surface electron density
Repulsion by Pauli principle
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ESDIADElectron Stimulated Desorption Angular
Distribution
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NH3, H2O/ Ni(111)
Czyzewski, Maday, Yates Phys.Rev.Lett. 32,
777(1974).
NH3 O/Ni(111)
H from NH3
H2O
H2O O/Ni(111)
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Photo stimulated desorption in accelerators
CERN 99-05, Dynamic outgassing, O.Groebner
Total radiation power
W
E GeV I mA r m bending radius
Photon flux per circumference m-1
Total gas desorption
Dynamic pressure rise
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D beam dose mAh
a0.61
Straight line constant S
Data for OFHC copper
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Before degass process
After degass process
! High temperature degass is efficient For
thermal outgassing. Not so efficiebt for photo
induced outgassing.
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Beam induced gas desorption
ppressure in the beam line
Particle balance
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Low energy photon induced desorption PSD
Ag plated
D2
H2
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Electron induced desorption from cryogenic
surfaces
Bass, Sanche Low Temperature Physics 29, 202
(2003).
O- desorption Dissociative Electron Attachment
(DEA)