Primary ion beam (Cs vs O)
electronegratiivty.where you are on the periodic table
7 Ion source design
8 Why ionization?
9 Metrics of ionization performance?
- Efficiency (molecules/ion) -> lower number better
- Selectivity: diversity of molecules that are ionized (tradeoff depends on application)
- Fragmentation: soft (molecular ions only) vs. hard (fragment ions produced) -> tradeoffs depending on application
- Adducts/molecular interferences made: H+ (EI), Ar+, O+ (in ICP), Na+ (in ESI)
- Intensity (beam “brightness”. Brighter beams require physically larger instruments)
- Stability
- Collimation, energy distribution of ions
10 Types of ion sources
10.1 TIMS
10.1.1 Principles
10.1.2 Metrics
10.1.3 Uses/applications
10.1.4 Arcane knowledge/decision points
Filament choice
Ionization temperature
Ionization efficiency
Activators
Positive vs. negative ionization
Spikes
10.2 EI
10.2.1 Principles
10.2.2 Metrics
10.2.3 Uses/applications
10.2.4 Arcane knowledge/decision points
Noble gas
Time zero
Trap current
Accelerating voltage
Electron energy
Ion repeller
Trap voltage
Source plates
Half-plate
Z-plate
Octopole/flatopole
Stable isotopes
Electron energy
Linearity vs. sensitivity
Trap
Beam tightness, fragmentation patterns
Extraction
Sensitivity vs. linearity/recombination/scrambling
Source pressure
Sensivity vs linearity/recombination
Bellows pressure / capillary
Bleedout rate
R-plate
10.3 SIMS
10.3.1 Principles
10.3.2 Metrics
10.3.3 Uses/applications
10.3.4 Arcane knowledge/decision points
Beam intensity
Beam size
Beam energy density
Ion microprobe vs ion microscope
10.4 ICP
10.4.1 Principles
10.4.2 Metrics
10.4.3 Uses/applications
10.4.4 Arcane knowledge/decision points
10.5 MALDI
10.5.1 Principles
10.5.2 Metrics
10.5.3 Uses/applications
10.5.4 Arcane knowledge/decision points
10.6 ESI
10.6.1 Principles
10.6.2 Metrics
10.6.3 Uses/applications
10.6.4 Arcane knowledge/decision points
10.7 CI
10.7.1 Principles
10.7.2 Metrics
10.7.3 Uses/applications
10.7.4 Arcane knowledge/decision points
Type of chemical ionization
Flow-tube
(acetate, iodide, or water (PTR))
Atmospheric pressure drift tube
EESI
Temperature stability
Ionization pressure
Fragmentation tradeoffs