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atomic Mass Spectrometry

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Chapter 11, Skoog, Holler, and Nieman, Principles of Instrumental Analysis – PowerPoint PPT presentation – PowerPoint PPT presentation

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Title: atomic Mass Spectrometry


1
Atomic Mass Spectrometry
Chapter 11
Chapter 11
Chapter 11
Chapter 11
Chapter 11
Chapter 11
Chapter 11
Chapter 11
Chapter 11
Chapter 11
Chapter 11
Chapter 11
Chapter 11
Chapter 11
Chapter 11
Chapter 11
Chapter 11
Chapter 11
Chapter 11
Chapter 11
Chapter 11
Chapter 11
Chapter 11
Chapter 11
Chapter 11
Chapter 11
Chapter 11
Chapter 11
Chapter 11
Chapter 11
Chapter 11
Chapter 11
Chapter 11
Chapter 11
Chapter 11
Chapter 11
Chapter 11
Chapter 11
Chapter 11
Chapter 11
Chapter 11
Chapter 11
Chapter 11
Chapter 11
Chapter 11
Chapter 11
Chapter 11
Chapter 11
Chapter 11
Chapter 11
Chapter 11
Chapter 11
Chapter 11
Chapter 11
Chapter 11
Chapter 11
Chapter 11
Chapter 11
Chapter 11
Chapter 11
Chapter 11
Chapter 11
Chapter 11
Chapter 11
Chapter 11
Chapter 11
Chapter 11
Chapter 11
Chapter 11
Chapter 11
Chapter 11
Chapter 11
Chapter 11
2
Atomic Weights in Mass Spectrometry
3
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4
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5
Componetnts of a Mass Spectrometer
10-5 to 10-8 torr
Gaseous ion sources
Mass analyzer
Ion transducer
Signal processor
Ion inlet
Vacuum pump
6
Discrete Dynode Eectron Multiplier
Ion beam
Detector slit
-1900V
-1700V
-1500V
-1300V
-1100V
-900V
-700V
-500V
-300V
-100V
Electrons
-2000V
-1800V
-1600V
-1400V
-1200V
-1000V
-800V
-600V
-400V
-200V
mA
7
Continuous Dynode Electron Multiplier
Resistive conductive surface
2kV
GND
8
Quadrupole Mass Spectrometer
Ions with stable trajectories
Ions with unstable trajectories
Ion source
Dc and ac oltages
9
High-Pass Mass Filter
Positve dc potential
Superimposed ac potential
Ions enter with the same kinetic energy.
Ions with lower mass are more affected by ac
potential and have unstable trajectories.
Ions with higher mass are less affected by ac
potential and have stable trajectories.
Positive ions are focused by dc potential.
Ions are defocused by the ac potential.
10
Low-Pass Mass Filter
Negative dc potential
Superimposed ac potential
y
z
Ions enter with the same kinetic energy.
Ions with higher mass are more affected by ac
potential and have unstable trajectories.
Ions with lower mass are less affected by ac
potential and have stable trajectories.
Positive ions are defocused by dc potential.
Ions are defocused by the ac potential.
11
Quadrupole Mass Filter
Ion source
Ions with stable Trajectories.
y
x
z
12
Mass Scan with Quadrupole Analyzer
1500
200
1000
100
dc potential (V)
500
Radio frequency potential(V)
0
0
-500
-100
-1000
-200
-1500
Time
m/z
13
Time-of-Flight Mass Spectrometer
Ions spread due to different velocities.
Acceleration region
Drift tube
Ion detector
Ions are accelerated by an electric field pulse
(103-104V) to the same kinetic energy.
A laser pulse (0.25 ms) ionize the sample.
Vacuum
m/e
Laser
14
Double Focusing Mass Spectrometer
Lighter ions
31o 50
Spark source
Magnetic analyzer
Magnetic field separates ions according to m/z.
Accelerating slit
Heavier ions
Focal plane
Electrostatic analyzer
90o
The electrostatic field serves to focus a narrow
band of knietic energies.
Photographic plate
15
ICP/MS
Hydride generation
Sampling cone
Ion lenses
Skimmer cone
GC SFC
Coolant flow
Quadruples
Electrothermal vaporization
Spray chamber
Nebulizer
Electron multiplier
Auxiliary flow
Flow injection
HPLC
Diffusion pumps
Expansion stage
Nebulizer flow
Solution sample
16
Standard Rock Sample by Laser Ablation ICPMS
28Si
56Fe
27Al
Channel counts
24Mg
23Na
16O
40Ar
39K
14N
40Ca
12C
48Tl
0
20
40
60
17
Suggestions Appreciated! Chemistry
Depatement, Shiraz University,
IRAN nzmaleki_at_gmail.com Sites.google.com/site/simi
nstrumentslab
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