Page 5 - Instrumental Analysis - Pharm D Clinical- 07-PA403

UV-visible Spectrophotometry

Wave properties of EMR

1- Wavelength (λ) (Lambda):

• It is the distance between successive maxima or minima of a wave.
• For ultraviolet and visible electromagnetic radiation, the wavelength

is usually expressed in nanometers (1 nm = 10–9 m), and for infrared
radiation it is given in micrometers (1 μm = 10–6 m).

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Wave properties of EMR

2- Frequency (ν) (Nu):

• It is the number of oscillations (waves) that occur per unit time.
• The unit of frequency is the hertz (Hz), which corresponds to one

wave per second, 1 Hz = 1 s–1.
• A frequency of 106 s–1 is said to be 106 Hz, or 1 megahertz (MHz).
• The relationship between wavelength and frequency is:

c = ν λ = 3 x 108 m s–1 = 3 x 1010 cm s–1

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