MassSpecAcademy/ion_source_design.qmd at main · mtrems/MassSpecAcademy · GitHub

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---
title: "Ion source design"
---


# Why ionization?


# 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

# Types of ion sources

## TIMS

### Principles

### Metrics

### Uses/applications

### Arcane knowledge/decision points

#### Filament choice

#### Ionization temperature

#### Ionization efficiency

#### Activators

#### Positive vs. negative ionization

#### Spikes


## EI {@sec-source-EI}

### Principles


### Metrics

### Uses/applications

### 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

## SIMS

### Principles


### Metrics

### Uses/applications

### Arcane knowledge/decision points

#### Primary ion beam (Cs vs O)

electronegratiivty.where you are on the periodic table

##### Cs reactions/implantation

#### Beam intensity


#### Beam size

#### Beam energy density

#### Ion microprobe vs ion microscope

## ICP

### Principles

### Metrics

### Uses/applications

### Arcane knowledge/decision points


## MALDI

### Principles

### Metrics

### Uses/applications

### Arcane knowledge/decision points

## ESI

### Principles

### Metrics

### Uses/applications

### Arcane knowledge/decision points

## CI

### Principles


### Metrics

### Uses/applications

### 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