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Clinical Pharmacy-Pharm D Level Three 2 Semester 2024/2025 Pharmaceutical Technology (PT 607)

where
d= resolving power (nm)
α = half opening angle of objective (radians)

V= accelerating voltage
Problem:
Determine the maximum resolution in nm of an electron microscope when the

applied voltage is 100000 volts, and the value of alpha is 0.01 radians.
Solution:
α = 0.01
V=100000

d=0.753/α√V
d=0.753/ . √
=0.23nm

3.Transmission and Scanning Electron Microscopy

Advantages Disadvantages

1. Particles are individually 1. Very expensive
examined 2. Time consuming sample
2. Visual means to see sub-micron preparation
specimens
3. Particle shape can be measured 3. Materials such as emulsions
difficult/impossible to measure
4. Not for routine use

4.Automatic and Image Analysis Microscopes

Advantages Disadvantages

1. Faster and less operator 1. Can be very expensive
fatigue than manual 2. No human judgment retained

2. No operator bias e.g. to separate out aggregates,
select or reject particles etc.
(unlike semi-automatic)

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