1. Ionization and Mass Analyzers Ionizations –Electron Ionization - “hard” –Chemical Ionization - “soft” –MALDI - desorption –FAB - desorption –Laser Post Ionization - increase signal! –Ion Bombardment (SIMS) - soft or hard Depends on ion fluence Mass Analyzers –Analyze all mass/charge Time-of-flight –Pre- Select Ions Quadropole Magnetic or Electric Sectors

2. Electron Ionization Molecule + e - molecule + + 2e - Four electromagnetic poles Rapidly oscillating field If mass of ion and frequency of oscillation are comparable then the ion will oscillate towards the detector and be measured A certain mass range can be selected depending on the pole diameter Quadropole Mass Analyzer

3. Electrostatic and Magnetic Sectors http://www.cea.com/cai/simsinst/m_anal.htm B = strength of magnetic field V = ion accelerating voltage r = radius of ion curvature m = mass of ion z = charge of ion focus mass separate M = 1-50 (change by changing B)

4. Secondary Ion Mass Spectrometry “Ionization” Static SIMS = < 1 x 10 13 ions/cm 2 Ga + - + e- 1 0 ion 2 0 particles

5. Time-of-Flight Analyzer d Field Free Region +V M+M+ MCP detector -V-V V = stage voltage d = length of field free region V = voltage of detector e = charge on an electron 1.6 x 10 -19 C t = time for ion to reach detector m = mass v = velocity Sample

6. TOF-SIMS Instrument

7. Laser Postionization (LPI) Postionization parameters Postionization parameters: 800 nm, 150 fs laser pulses, 8.5 x 10 12 W/cm 2 power density Laser Beam

8. TOF-SIMS Molecule-Specific Imaging molecule-specific image Si + Cu + Ag + m/z, +ions total ion image 570 µm x 570 µm Intensity copper grid affixed to silicon substrate with silver paste Ion Gun x y

9. TOF-SIMS Identification of Plasma Membrane Lipids m/z 369 cholesterol m/z 385 (M-H) + DPPE – dipalmitoylphosphatidylethanolamine m/z 552 m/z 142 +2H * * m/z 682 (M+H) + + -

10. C. M. McQuaw; A. G. Sostarecz et. al. Langmuir 2005. 250 µm x 250 µm Are there Lipid Domains in the Inner Leaflet of the Membrane? Total Ion DPPE/Cholesterol - + 552 Cholesterolcholesterol DPPEDPPEIntensity A. G. Sostarecz; C. M. McQuaw et. al. J. Am. Chem. Soc. 2004. Au

11. Multi-Isotope Imaging Mass Spectrometry endothelial cell Image from Claude Lechene Harvard Medical School 14 N 14 N nucleus lamellipodia Atomic Mass Images

12. MIMS is a Secondary Ion Mass Spectrometry Technique http://www.cea.com/cai/simsinst/m_anal.htm B = strength of magnetic field V = ion accelerating voltage r = radius of ion curvature m = mass of ion z = charge of ion focus mass separate M = 1-50 (change by changing B) - + e- 1 0 ion 2 0 particles

13. MIMS uses an Electrostatic and Magnetic Sector Mass Analyzer *** MIMS analysis is performed as a collaborative project with Dr. Claude Lechene at the National Resource for Imaging Mass Spectrometry at Harvard Medical School focus mass separate ion 1 Image from Claude Lechene 84 % 16 % 14 N 14 N