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Spectroscopy
Instrument components
The EM Spectrum
The EM spectrum explained

EM Spectrum and Analytical Chemistry

Radiation Type	Radiation Source	Frequency Range (Hz)	Wavelength Range	Type of Transitions
gamma rays		1020 - 1024	<10-12 m	nuclear
X-rays		1017 - 1020	1nm - 1 pm	inner electron
ultraviolet	deuterium lamp	1015 - 1017	400 nm - 1 nm	outer electron. Electronic transitions, vibrational fine structure
visible	Tungsten lamp	4 - 7.5 x 1014	750 nm - 400 nm
near-infrared	Tungsten, dye laser	1 x 1014 - 4 x 1014	2500 nm - 750 nm (2.5 um - 750 nm)	outer electron molecular vibrations. Vibrational transitions, rotational fine structure
infrared	nerst glower, globar, Xe,Ar, discharge lamp	1013 - 1014	250,000 - 2,500 nm (25um - 2.5 um)	outer electron, molecular vibrations. Vibrational transitions, rotational fine structure
microwaves		3 x 1011 - 1013	250,000 - 1,000,000,000 nm (1 mm - 25 um)	molecular rotations,electron spin flips*, Rotational transitions
radio waves		<3 x 1011	>1 mm	nuclear spin flips*
* energy levels split by a magnetic field.

The Colors of Visible Radiation ¹

Wavelength Range nm	Color seen by Instrument Absorption color	Color seen by Human Eye Complement color
400 - 465	Violet	Yellowish green
465 - 482	Blue	Yellow
482 - 487	Greenish blue	Orange
487 - 493	Blue green	Red orange
493 - 498	Bluish green	Red
498 - 530	Green	Red purple
530 - 559	Yellowish green	Reddish purple
559 - 571	Yellow green	Purple
571 - 576	Greenish yellow	Violet
576 - 580	Yellow	Blue
580 - 587	Yellowish orange	Blue
587 - 597	Orange	Greenish blue
597 - 617	Reddish orange	Blue green
617 - 780	Red	Blue green

Reference:
1. "Analytical Absorption Spectroscopy", D.B. Judd; M.G. Melon (Ed.)
Chap. 9, Wiley, New York, 1950.



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