Biomedical Engineering Reference
In-Depth Information
1
Introduction to Spectroscopy
By the Sun and its brightness
Quran, 91:1
History
The first spectroscopic experiments were recorded by Sir Isaac Newton
in the seventeenth century in which he used, for the first time, a glass
prism for spectral dispersion and introduced the term spectrum in his
classic volume Opticks (1704). The early nineteenth century saw major
achievements in spectroscopy with the invention of optical grating
(1500 lines in the Sun's spectrum) by Joseph Fraunhofer (Figure 1.1). He
developed the first grating spectroscope and by using this spectroscope,
German physicist Kirchhoff detected sodium in the Sun's spectrum
(Figure 1.2). Further developments in spectroscopic studies were achieved
by many scientists in the late nineteenth and twentieth century. The fol-
lowing achievements have contributed tremendously to the understand-
ing of spectroscopy.
J. J. Balmer discovered the Balmer series of lines in the hydrogen spectrum
in 1885. Discovery of concave grating by Henry A. Rowland in 1887 revolu-
tionised experimental spectroscopy. Discovery of electrons and the atomic
nucleus by English physicists J. J. Thompson (1897) and Ernest Rutherford
(1911), the first principles of quantum theory by Max Planck  (1900),
discovery of quantum mechanics by Werner Heisenberg (1932) and Erwin
Schrodinger  (1933), and the first real quantitative spectral analysis by
G. Scheibe, W. Gerlach, and E. Schweitzer (1925) [1-3].
Spectroscopy can be defined as an analysis technique to study the interac-
tion of electromagnetic radiation with atoms and molecules. The scattering
of a light after interaction with matter grades into its component energies
(colours). The resultant dissection of energies can be used to analysis that
matter's physical properties. Matter is composed of atoms; in a stable state
the atoms of molecules are in an electronic, vibrational, and rotational state.
When electromagnetic radiation interacts with these stable atoms or mol-
ecules, they may undergo transitions in an energy state, that is, stable state
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