1. Intermediate and High Voltage Microscopy
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2. د. عمر عبد القادر

3. The greater the accelerating voltage the shorter the l
Therefore, a 50,000 volt (50 kV) electron has a wavelength of nm and a 1MeV electron has a wavelength of nm!
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4. A million volt (MeV) TEM must maintain an accelerating voltage that is stable to within 0.5 volts.
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5. A million volt (MeV) TEM must maintain an accelerating voltage that is stable to within 0.5 volts. With this coupled with a field emission source one can achieve resolutions that are in the range of 0.5Å
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6. Hitachi 3 MeV is the most powerful TEM ever made
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7. Operator Hitachi 3 MeV is the most powerful TEM ever made
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8. It requires its own separate building
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9. Advantages of High Voltage EM
Increased Resolution: Although still a long way from a theoretical resolution of nm. the best actual resolution has been achieved with a 1 MeV field emission TEM.
Nanocrystalline structure of silicon
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10. Advantages of High Voltage EM
Increased Resolution: Although still a long way from a theoretical resolution of nm. the best actual resolution has been achieved with a 1 MeV field emission TEM.
1 MeV kV kV
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11. Advantages of High Voltage EM
Increased Specimen Penetration: As accelerating voltage increases the ability of the beam to penetrate also increases.
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12. Dendrite in 3 mm thick section
Advantages of High Voltage EM
Increased Depth of Information: The great depth of information allows an entire thick section to be viewed at once.
Dendrite in 3 mm thick section
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13. Mitotic cell stereo pair
Advantages of High Voltage EM
Increased Depth of Information: It also allows for stereo pairs to be created from thick sections.
Mitotic cell stereo pair
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14. Advantages of High Voltage EM
Reduced Beam Damage: The increased speed of the electrons actually decreases the likelihood of an inelastic collision.
The same section viewed with 1 MeV vs. 100 kV will have less contrast due to fewer scattered electrons
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15. The Boulder Laboratory for 3-Dimensional Electron Microscopy of Cells is located at the University of Colorado. It is a National Resource Center supported by the National Center for Research Resources (NCRR) at the National Institutes of Health (NIH).
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16. Intermediate Voltage (200-400 kV)
JEOL JEM-4000FX
Hitachi H-9000NAR
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