Tutorial: SIMS Basics - University of...

Tutorial: SIMS Basics

Noriko Kita (WiscSIMS, UW-Madison) HighRes2015 1

•  Overview of SIMS

•  Sputtering process

•  Electron-gun

•  Mass spectrum

•  Detectors

•  WiscSIMS modification

•  Isotope Analyses

Please stop me anytime for questions!

Secondary Ion Mass Spectrometer (SIMS)

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IMS 1280

Secondary Ions

Electron

Beam ?e?e

Primary Ions+Cs

Sample

?O

Electrostatic Lens

Electrostatic Deflector

Aperture or Slit

Collector

Motion Axis

Flight

Tube

Energy Slit

Primary Beam

Mass Filter

Field Aperture

Entrance Slit and

Contrast Aperture

Normal Incidence

Electron Gun

Airlock

Sample Stage

Sample

Duo-

Plasmatron

Cs-

Source

Detectors

Magnet

Electrostatic

Analyzer (ESA)

Sample & Secondary Ions Electron Gun Detection

Primary Ion Source

ESA Magnet CAMECA IMS 1280

•  Primary Ions (Cs+/O−)

•  Secondary Ions from sample

•  Electron-gun

•  Electrostatic Analyzer (ESA)

•  Sector Magnet

•  Ion Detectors

Double Focusing Mass Spectrometer


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Double Focusing Mass Spectrometers

§  Large radius (high mass resolution: M/ΔM ≥ 5,000)

Ø  IMS1270/1280/1280HR: Stable isotope, Geochronology, Nuclear forensic

Ø  SHRIMP: Geochronology (zircon U-Pb ages)

Ø  NanoSIMS: High spatial resolution (50nm beam) Imaging, biological applications

§  Conventional SIMS (low mass resolution): IMF 7f/ 7fGeo:

TOF (Time of flight): Shallow depth analysis, thin film

--------------------------- R = 585 mm

----------------- R = 1,000 mm

------- R = 120 mm

Sector Magnet radius


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Analytical volume 2µm - 10µm diameter ~1µm depth à 0.3 ng to a few pg

Surface analysis - trace element - elemental mapping - isotope ratios

Secondary ions are produced by the sputtering of primary ions

±10kV

Secondary Ion

Primary Ion (+10kV/−13kV)

Magnetic Field Electrostatic Field

Double focusing Mass Spectrometer

18O 16O

Ion counters Sample

E-gun

Simplified Schematic of SIMS

SIMS Analysis Spots

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selected [Bralower et al., 1995; Kelly et al., 1998; Tripatiet al., 2003]. The calcareous nannofossil biozonation con-structed for this section indicates that the stratigraphyextends relatively uninterrupted from the late Paleocenethrough the early Eocene (zones NP9 to NP14a) [Bralower and

Mutterlose, 1995]. Accordingly, the age model employedin this study was constructed using the published nanno-fossil biostratigraphy [Bralower and Mutterlose, 1995] andthe ages assigned to the datums upon which this biozona-tion is based [Berggren et al., 1995]. Thus, age estimates

Table 1. Sample Core Depths, Assigned Calcareous Nannofossil Zones, and Estimated Agesa

Datumb Biozone Sample ID Age (Ma)

SedimentationRate, Linear(m/Myr)

Depth,865B (mbsf)

Depth,865C (mbsf)

FO D. sublodoensis NP14 865B 9H‐4 10 49.70 2.67 79.60LO D. orthostylus NP13 865B 9H‐6 70 50.60 4.00 83.20FO D. lodoensis NP12 865B 10H‐4 60 52.85 2.84 89.60FO T. contortus NP11 865B 10H‐5 111/865C

11H‐2 13453.61 2.64/5.6 91.61 91.74

FO D. diastypus NP10 865B 11H‐6 70/865C12H‐3 138

55.00 7.62/7.94 102.20 102.68

FO D. multiradiatus NP9 865C 13H‐5 80 56.20 9.93 114.60

aCore depths [Bralower and Mutterlose, 1995] and ages [Berggren et al., 1995] assigned to various nannofossil biostratigraphic datums for calculatinglinear sedimentation rates that were used to construct a chronostratigraphic framework for the late Paleocene–early Eocene section from Site 865.

bFO, first occurrence; LO, last occurrence.

Figure 1. (a) Scanning electron microscope (SEM) image of a test of Morozovella velascoensis (ODPSite 865) in edge view. (b) Enlargement of the chamber wall and muricae. Several mural pores are high-lighted by arrows. Blade‐shaped diagenetic crystallites are cemented on top of the biogenic muricae.(c, d) High contrast SEM backscattered electron images of a polished morozovellid test. Figure 1c is across section taken perpendicular to the coiling axis of a M. velascoensis test from the 300–355 mm sievefraction, with a width of 450 mm (Hole 865C, 103.10 mbsf). Figure 1d is an enlargement of a cross sectionof the same test, showing muricae fused into a keel‐like structure at the test periphery. (e) SEM image ofthe gold‐coated sample displaying a ∼10 mm ion microprobe pit for d18O analysis. Textures in the pit areetched by the Cs+ beam.

KOZDON ET AL.: d18O IN MURICAE BASES BY ION MICROPROBE PA3206PA3206

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Cs+ primary beam 10-15 µm spots

Comet sample return; Nakashima et al. (2012)

Cs+ primary beam 1-2 µm spots

Foraminifera; Kozdon et al. (2011)

Primary Ion intensity ~ 2 nA Precisions of oxygen isotope ratios ~ 0.3‰

3 pA 1-2 ‰

“Large” Spot “Small” Spot

Most of elements in periodic table are ionized

HighRes2015 6 Modified from Evans Analytical Group: http://www.eaglabs.com/mc/sims-theory.html

Cs+/Sec(−) O−/Sec(+)

- Noble gases do not ionize. - Nitrogen in carbon bearing phase: CN−

Ionization efficiency varies significantly from 0.1 to 10%

Secondary Ions

±10kV

Primary Ions Cs: +10kV O−: −13kV

Sample Higher electro-negativity: O−, C−, S−, Si−

Higher ionization tendency: Mg+, Ca+, Pb+

Secondary Ions: Ionization Efficiency

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Ionization efficiencies = (N of secondary ions)/ (N of atoms sputtered)

O− in silicate, carbonates, oxide minerals ~10%

C− in carbonates ≤ 0.3%

Si− in quartz ~ 1%

Secondary Ion intensities Calcite (CaCO3) C− = 2×107 cps O− = 2×109 cps Ca− ~0 (ionized as CaO−) Quartz (SiO2) O− = 2×109 cps Si− = 1×108 cps

Instrumental bias on isotope ratio = (18O−/16O−)SIMS /(18O/16O)True

oxygen isotope (18O/16O) in silicate, carbonates, oxide minerals: ±10‰

carbon isotope (13C/12C) in calcite: −40‰

silicon isotope (30Si/28Si) in quartz: −30‰

Sputtering of samples

HighRes2015 8 IMS 1280

Secondary Ions

Electron

Beam ?e?e

Primary Ions+Cs

Sample

?O

Electrostatic Lens


Aperture or Slit

Collector

Motion Axis

Flight

Tube

Energy Slit

Primary Beam

Mass Filter

Field Aperture

Entrance Slit and

Contrast Aperture

Normal Incidence

Electron Gun

Airlock

Sample Stage

Sample

Duo-

Plasmatron

Cs-

Source

Detectors

Magnet

Electrostatic

Analyzer (ESA)

−10kV

Cs+ +10kV

+10kV

O− −13kV

Ion Sources

Sample

Impact Energy 20-23 keV

Entrance of secondary optics (Main chamber door is opened)

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Sample holder Insulator

Sample holder is held at ± 10kV Sample holders (original 25mm and new 32 mm)

20 mm 22 mm

Sputtering Process

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Ejection of electron from sample surface causes charging of sample --- electron gun

Initial kinetic energy of secondary ions

--- double focusing mass spectrometer Formation of multiple atomic and molecular ions, divalent ions

--- high mass resolution power by large radius sector magnet

These factors determined the performance of the instrument for high precision stable isotope analyses

Primary ion implantation and ejection of atoms from interior

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IMS 1280

Secondary Ions

Electron

Beam ?e?e

Primary Ions+Cs

Sample

?O

Electrostatic Lens


Aperture or Slit

Collector

Motion Axis

Flight

Tube

Energy Slit

Primary Beam

Mass Filter

Field Aperture

Entrance Slit and

Contrast Aperture

Normal Incidence

Electron Gun

Airlock

Sample Stage

Sample

Duo-

Plasmatron

Cs-

Source

Detectors

Magnet

Electrostatic

Analyzer (ESA)

-  Primary ions are implanted to the interior of sample.

-  Atoms in the sample are displaced by collision cascade.

Primary Ion 133Cs+ Impact energy 20 keV

Lattice structure is destroyed: amorphous layer (~30nm)

0V

-10kV

Some atoms are ejected from surface

“Sputtering"

Secondary ion production and extraction to mass spectrometer

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IMS 1280

Secondary Ions

Electron

Beam ?e?e

Primary Ions+Cs

Sample

?O

Electrostatic Lens


Aperture or Slit

Collector

Motion Axis

Flight

Tube

Energy Slit

Primary Beam

Mass Filter

Field Aperture

Entrance Slit and

Contrast Aperture

Normal Incidence

Electron Gun

Airlock

Sample Stage

Sample

Duo-

Plasmatron

Cs-

Source

Detectors

Magnet

Electrostatic

Analyzer (ESA)

0V

-10kV

Extraction

Sample High Voltage

Most (>90%) atoms and molecules are neutral. Some are ionized and are accelerated by 10kV electro-static field.

e

e e

e

e e e e

e

e

e

e e e

e

e

e

e e

e e

e e

e e

e

atomic ions (−)

neutral atoms

molecular ions (−)

neutral molecules

Electrons (−) e


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IMS 1280

Secondary Ions

Electron

Beam ?e?e

Primary Ions+Cs

Sample

?O

Electrostatic Lens


Aperture or Slit

Collector

Motion Axis

Flight

Tube

Energy Slit

Primary Beam

Mass Filter

Field Aperture

Entrance Slit and

Contrast Aperture

Normal Incidence

Electron Gun

Airlock

Sample Stage

Sample

Duo-

Plasmatron

Cs-

Source

Detectors

Magnet

Electrostatic

Analyzer (ESA)

0V

-10kV atomic ions (−)

neutral atoms


neutral molecules

Electrons (−) e

Extraction

Sample High Voltage

e

e e

e

e e e e

e

e

e

e e e

e

e

e

e e

e e

e e

e e

e

Gold coat e e e e e e

Electron is easily ejected out from the sample by the same -10kV field !

Your samples are insulators!!


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IMS 1280

Secondary Ions

Electron

Beam ?e?e

Primary Ions+Cs

Sample

?O

Electrostatic Lens


Aperture or Slit

Collector

Motion Axis

Flight

Tube

Energy Slit

Primary Beam

Mass Filter

Field Aperture

Entrance Slit and

Contrast Aperture

Normal Incidence

Electron Gun

Airlock

Sample Stage

Sample

Duo-

Plasmatron

Cs-

Source

Detectors

Magnet

Electrostatic

Analyzer (ESA)

0V


neutral atoms


neutral molecules

Electrons (−) e

Extraction

Sample High Voltage

e

e e

e

e e e e

e

e

e

e e e

e

e

e

e e

e e

e e

e e

e

What will happen if electrons are lost?

Secondary ions can not pass through the mass spectrometer,

which is tuned for -10kV extraction voltage.

-9.9kV -9.5kV -9.0kV


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IMS 1280

Secondary Ions

Electron

Beam ?e?e

Primary Ions+Cs

Sample

?O

Electrostatic Lens


Aperture or Slit

Collector

Motion Axis

Flight

Tube

Energy Slit

Primary Beam

Mass Filter

Field Aperture

Entrance Slit and

Contrast Aperture

Normal Incidence

Electron Gun

Airlock

Sample Stage

Sample

Duo-

Plasmatron

Cs-

Source

Detectors

Magnet

Electrostatic

Analyzer (ESA)

0V


neutral atoms


neutral molecules

Electrons (−) e

Extraction

Sample High Voltage

e

e e

e

e e e e

e

e

e

e e e

e

e

e

e e

e e

e e

e e

e

What would happen if we can not supply any electrons?

?? kV

Electrostatic discharge! …on your sample?

Electron Gun for Charge Compensation


Secondary Ions

Electron

Beam ?e?e

Primary Ions+Cs

Sample

?O

Electrostatic Lens


Aperture or Slit

Collector

Motion Axis

Flight

Tube

Energy Slit

Primary Beam

Mass Filter

Field Aperture

Entrance Slit and

Contrast Aperture

Normal Incidence

Electron Gun

Airlock

Sample Stage

Sample

Duo-

Plasmatron

Cs-

Source

Detectors

Magnet

Electrostatic

Analyzer (ESA)

Electron Gun

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0V

Deceleration

Electron Cloud (50µA, 100-150µm): electron energy =0 eV

e e e e

e e e e e

e e

e e

e e e e

e e e e e

e e e e e

e e e e

electron is attracted to sample surface until the charge is compensated.

+++++++ When charge build up by sputtering

Acceleration voltage: -10kV

-10kV

Electron gun: -10 kV Sample acceleration: -10 kV

Sample

Electron Gun for Charge Compensation

IMS 1280

Secondary Ions

Electron

Beam ?e?e

Primary Ions+Cs

Sample

?O

Electrostatic Lens


Aperture or Slit

Collector

Motion Axis

Flight

Tube

Energy Slit

Primary Beam

Mass Filter

Field Aperture

Entrance Slit and

Contrast Aperture

Normal Incidence

Electron Gun

Airlock

Sample Stage

Sample

Duo-

Plasmatron

Cs-

Source

Detectors

Magnet

Electrostatic

Analyzer (ESA)

Double Focusing Mass Spectrometer


Secondary Ions

Electron

Beam ?e?e

Primary Ions+Cs

Sample

?O

Electrostatic Lens


Aperture or Slit

Collector

Motion Axis

Flight

Tube

Energy Slit

Primary Beam

Mass Filter

Field Aperture

Entrance Slit and

Contrast Aperture

Normal Incidence

Electron Gun

Airlock

Sample Stage

Sample

Duo-

Plasmatron

Cs-

Source

Detectors

Magnet

Electrostatic

Analyzer (ESA)

ESA Magnet

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Initial Kinetic Energy of Secondary Ions

Sputtering process may provide initial kinetic energy to ions

-10kV

0V

Ion without initial kinetic energy

Acceleration by electrostatic field Vs

mivi2/2 =qeVs vi

Ion with initial kinetic energy and angles

v0

v = vi + v0

Trajectory of ions with variable energies and angles will be different

Sample

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Electrostatic Analyzer (ESA)

IMS 1280

Secondary Ions

Electron

Beam ?e?e

Primary Ions+Cs

Sample

?O

Electrostatic Lens


Aperture or Slit

Collector

Motion Axis

Flight

Tube

Energy Slit

Primary Beam

Mass Filter

Field Aperture

Entrance Slit and

Contrast Aperture

Normal Incidence

Electron Gun

Airlock

Sample Stage

Sample

Duo-

Plasmatron

Cs-

Source

Detectors

Magnet

Electrostatic

Analyzer (ESA)

ESA

Energy slit

faster ions

slower ions

ESA

Energy Slit

Ions with variable angles

ESA

Energy Slit

Ions with variable energy

Ions with variable angles: Focus Ions with variable energy: Dispersion Focus

Dispersion

Magnet

Exit slit

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Sector Magnet: Ions with different masses

IMS 1280

Secondary Ions

Electron

Beam ?e?e

Primary Ions+Cs

Sample

?O

Electrostatic Lens


Aperture or Slit

Collector

Motion Axis

Flight

Tube

Energy Slit

Primary Beam

Mass Filter

Field Aperture

Entrance Slit and

Contrast Aperture

Normal Incidence

Electron Gun

Airlock

Sample Stage

Sample

Duo-

Plasmatron

Cs-

Source

Detectors

Magnet

Electrostatic

Analyzer (ESA)

Magnet

Exit slit

m

m-1 m+1

Magnet separate ions with different mass

Magnet

Exit slit

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Sector Magnet: Ions with the same mass

IMS 1280

Secondary Ions

Electron

Beam ?e?e

Primary Ions+Cs

Sample

?O

Electrostatic Lens


Aperture or Slit

Collector

Motion Axis

Flight

Tube

Energy Slit

Primary Beam

Mass Filter

Field Aperture

Entrance Slit and

Contrast Aperture

Normal Incidence

Electron Gun

Airlock

Sample Stage

Sample

Duo-

Plasmatron

Cs-

Source

Detectors

Magnet

Electrostatic

Analyzer (ESA)

Magnet

Exit slit slower faster

different energy

Magnet

Exit slit

different angles Ions with different angles: Focus Ions with different energy: Dispersion

Similar to ESA

Focus Dispersion

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Double focusing mass spectrometer

Focus Ions with variable initial energy Focus ions with variable angles

Dispersions made by ESA and Magnet are coupled to focus ions with variable energy.

From Cameca IMS manual

Ions ejected with variable angles and energy

Magnet ESA

Ions ejected with variable angles

Energy slit

lens

Entrance slit

Exity slit

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Detailed schematics of IMS 1280 Primary Column Magnet (PBMF) Lens: 5 Deflector: 7 Stigmator: 2 Aperture: 2

Secondary optics Magnet ESA Lens: 10 Deflector: 6 Stigmator: 3 Hexapole: 3 Slit: 3 Aperture: 2 Detectors FC: 6 EM: 4 MCP ESA: 6

Electron Gun Coil: 2 Lens: 1 Deflector: 2 Quadrapole: 1

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Mass Spectrum and Stability (NMR)

17O: MRP ~ 4,000; 16O, 18O: MRP ~2,200

17O

16OH +0.0036 amu

18O

16O

0.0045 amu 10% height

Magnetic field is regulated by NMR sensor. Drift (ΔB) <5 ppm for 12 hours

Hall Probe

NMR Probe

NMR Probes

Flight Tube

NMR (Nuclear Magnetic Resonance) sensors between electro-magnets

*Hall Probe stability: ~30 ppm for 1 hour

MRP=(M/ΔM): mass resolving power

30 ppm

Multi-collectors

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Ion Transmission

Transmission vs. Mass resolution

0.01

0.10

1.00

10.00

100 1000 10000 100000Mass resolution

Re

lati

ve

tra

ns

mis

sio

n

IMS 6f (Cs+)

IMS 1270 (Cs+)

Nanosims 50 (C-)

CAMECA

17O 18O/16O

WiscSIMS IMS 1280

§  Oxygen 2 isotope >90%

§  C isotope >90%

§  Oxygen 3 isotope >70%

Large radius SIMS

Small radius SIMS

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Ion Detectors

§  FC (Faraday cup): Direct ion current measurements >106 cps

§  EM (electron multiplier): Pulse counting <106 cps

Series of dynodes (N~20): each ejects 2-3 electrons 108 electrons produced per single ion – detected as an electronic pulse

Stable Gain Slower response (sec) Thermal noise (~1000 cps) Amp

Ion current 2×109 cps = 3×10-11 A

R =1011 ohm

V = I × R

3V

Low noise <0.01 cps Fast response (20-70 ns) Gain drift

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Ion Detectors

§  FC (Faraday cup): Direct ion current measurements

§  EM (electron multiplier): Pulse counting

§  MCP (multi-channel plate): Direct ion imaging

•  Multi-collection FC system is originally designed by Finnigan MAT. •  Very similar to modern ICP-MS and TIMS instruments.

Magnet

Multi-collection system: 5 movable detectors (2FC, 3EM) 2 additional FCs on L2 and H2

Mono-collection system: 2FCs and 1 EM

Total 10

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Ion Detectors and Detection System

!Looked from the the side

Looked from the top

Magnet

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Types of analyses using SIMS

Spot analysis: High precision stable isotope analyses Trace element analyses

Scanning Ion Imaging (SII): NanoSIMS

Trace element, isotope mapping Resolution = Primary beam size (0.5µm - 3 µm)

Direct Ion Image:

IMS 1280/7f series works as “ion microscope”. MCP detection SCAPS detector (Hokkaido 1270 and Hawaii 1280) Resolution = Optical resolution (~0.5 µm)

Example of SII (Ushikubo et al. 2008)

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Modification of WiscSIMS IMS 1280: 6 holder airlock system (2009)

Option from Cameca: Original system only keeps one additional sample.

§  Reduced time for pumping individual samples §  Especially important for modern bio-minerals containing

more moistures and organic matters

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Modification of WiscSIMS IMS 1280 (UV light microscope, 2011)

Kita et al. (2015, JAAS)

IMS 1280 Optical microscope

Original: White halogen lump Resolution ~3.5 µm Chromatic abberation

UV light optics 356 nm LED HD camera Resolution ~1.3 µm * Replaced multiple optical components.

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New sample viewing software “Badgerscope©” (2012)

Kita et al. (2015, JAAS)

Image processing

New software to view HD-camera

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Modification of WiscSIMS IMS 1280: NanoDeflector (2014)

Defouilloy et al. (This meeting, poster)

Accuracy of aiming ≥1 µm Stage minimum step =1 µm Primary beam deflection minimum = 1µm

Apply additional voltage to beam deflector

Resolution: 0.1 µm

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Oxygen isotope analyses

Instrument is fully tuned including detector positions and magnetic field. -  Move to standard

grain in your sample.

-  Move to your analysis position.

click

36





-  Press START

Acquisition takes 3min

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37


During first 1 min, there will be series of scanning. This is called “DTFA Scan” that adjustment of primary beam misalignment against secondary ion optical axis.

Cs+

O-

DTFA (XY)

DTFA-Scan

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38

After the analysis: import new data to excel sheet

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Select next row

Click Macro-button

39

After the analysis: import new data to excel sheet

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HighRes2015 40





-  Move to next position

click

Repeat this 12 hours

Tutorial: SIMS Basics - University of...

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