Lecture- 9 simS Ndt SIMS Basic principles Instrumentation 令 Mass resolution Modes of analysis 令 Applications Non-Destructive AnalysiS (NDa) or Non-Destructive Testing(NDT)
Lecture-9 SIMS & NDT • SIMS ❖ Basic Principles ❖ Instrumentation ❖ Mass Resolution ❖ Modes of Analysis ❖ Applications • Non-Destructive Analysis (NDA) or Non-Destructive Testing (NDT)
Instrumentation Bombardment of a sample surface with a primary ion beam followed by mass spectrometry of the emitted secondary ions constitutes secondary ion mass spectrometry (sims). Ion Sources lon sources with electron impact ionization -Duoplasmatron: Ar, O2, o- Ion sources with surface ionization- Cst ion sources lon sources with field emission -Gat liquid metal ion sources Mass Analyzers Vacuum<10-6 torr Magnetic sector analyzer Quadrupole mass analyzer · Time of flight analyzer Ion Detectors Fa p araday cu Dynode electron multiplier Ion detectors Mass analyzers lon sources SIMS CAMECA 6F Mass analyzers http://www.youtube.com/watch?v=i0-kcjxznlstow1:50
Instrumentation SIMS CAMECA 6F Ion Sources • Ion sources with electron impact ionization - Duoplasmatron: Ar+ , O2 + , O- • Ion sources with surface ionization - Cs+ ion sources • Ion sources with field emission - Ga+ liquid metal ion sources Mass Analyzers • Magnetic sector analyzer • Quadrupole mass analyzer • Time of flight analyzer Ion Detectors • Faraday cup • Dynode electron multiplier Ip Is Ion sources Ion detectors Mass Analyzers Mass analyzers Vacuum < 10−6 torr http://www.youtube.com/watch?v=IO-KCjxznLs to~1:50 Bombardment of a sample surface with a primary ion beam followed by mass spectrometry of the emitted secondary ions constitutes secondary ion mass spectrometry (SIMS)
Cs ion source Duoplasmatron ion source 23456789 Primary beam mass filter Cameca Sims Immersion lens Sample 1011-12 Dynamic emittance matching A Transfer lens system B Liquid metal source Entrance slit s 9 Ga 10. 900 electrostatic analyzer 8 11. Energy slit S 12. Intermediate lens 1 7 13. 900 magnetic sector 14. Exit slit S3 15. Projection lenses 16. Projection deflector 17. Channelplate Accelerating voltage 19 18. Fluorescence screen Secondary ions have low kinetic 18 19. Electron multiplier energies from zero to a few 20. Faraday cup hundred ev. 1, L2 and L3-electromagnetic lens vww. eaglabs com/mc/sims-instrumentation html
Cameca SIMS Accelerating voltage Secondary ions have low kinetic energies from zero to a few hundred eV. L1 , L2 and L3 - electromagnetic lens http://www.eaglabs.com/mc/sims-instrumentation.html
Energy Analyzer and Mass spectrometer esa bends lower energy ions more strongly than higher energy ions. The sputtering process produces a range of ion energies. An energy slit can be set to intercept the higl energy ions. Sweeping the magnetic field in Ma provides the separation of ions according to mass-to-charge ratios in time sequence 2 B4.2 m/q et ESA 2V Electrostatic slit Mass Analyzer (MA) analyzer(ESa) Select the Ke B Select the m/e of ions Degree(r)of deflection of ions by the magnetic filed Magnet Sector Electrostatic depends on m/g ratio Sector V- ion acceleration voltage exit Point of radius of curvature of an ion slit d ouble focus Direction Ion focal plane Energy llector Focal plane Source exit https://www.youtube.com/watch?v=nuih9-6fm6uatn3:40-5:16 https://www.youtube.com/watch?v=ezvqzimbuq8tow2:06 http://www.youtube.com/watch?v=lxafw1rftiaatw1:00-4:12
Energy Analyzer and Mass Spectrometer ESA bends lower energy ions more strongly than higher energy ions. The sputtering process produces a range of ion energies. An energy slit can be set to intercept the high energy ions. Sweeping the magnetic field in MA provides the separation of ions according to mass-to-charge ratios in time sequence. Mass Analyzer (MA) Magnet Sector Electrostatic Sector E r - radius of curvature of an ion http://www.youtube.com/watch?v=lxAfw1rftIA at~1:00-4:12 Energy Focal plane Degree (r) of deflection of ions by the magnetic filed depends on m/q ratio. V - ion acceleration voltage https://www.youtube.com/watch?v=EzvQzImBuq8 to~2:06 https://www.youtube.com/watch?v=NuIH9-6Fm6U at~3:40-5:16
Basic equations of Mass spectrometry Ions kinetic e function of mv=zv accelerating voltage(v)and charge(z V ball centrifugal F=my/ r Centrifugal force force F=BEV L Applied magnetic field trimetal force rentz force Balance as ion goes mv/r=Bzv] through flight tube Combine equations to obtain m/z=br/2V Fundamental equation of mass spectrometry Change ' mass-to-charge(m/z)ratio by m/z =m/ changing V or changing B for singly charged ions NOTE: if B, v, z constant, then r-radius of circular ion path
Basic Equations of Mass Spectrometry 1 2 2 mv zV = 2 F mv R = / F Bzv = 2 mv R Bzv / = 2 2 m z B R V / / 2 = Ion’s kinetic E function of accelerating voltage (V) and charge (z). Centrifugal force Applied magnetic field Lorentz force Balance as ion goes through flight tube Fundamental equation of mass spectrometry Combine equations to obtain: Change ‘ mass-to-charge’ (m/z) ratio by changing V or changing B. NOTE: if B, V, z constant, then: r m m/z = m/e for singly charged ions r- radius of circular ion path r r r