Page 24 - Instrumental Analysis - Pharm D Clinical- 07-PA403

UV-visible Spectrophotometry

II- Prisms

• They act by refraction of light.
• Prisms are made of glass for use in visible region, while they are

made of quartz for use in UV region, since glass absorbs
wavelengths shorter than 330 nm.

Dispersion of light by a prism

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III- Gratings

• They act by diffraction of light.
• Grating consists of a large number of parallel lines ruled very close to each

other on aluminum or glass surface (up to 6000 line / mm).
• Grating is the most efficient dispersing system where the resulting

bandwidth is the smallest (best resolution).

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