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Chemistry - Spectroscopic techniques

Spectroscopic techniques

Spectroscopic techniques of analysis make use of the effect of
electromagnetic radiation on matter.

Atoms of different elements have different arrangements of electrons and
hence absorb and emit electromagnetic radiation to different extents.

Flame Emission spectroscopy is a simple form of qualitative analysis used
to identify the presence of particular elements in a compound by means of a
flame test.

Atomic Absorption spectroscopy (AAS) is a common form of quantitative
analysis, especially for determining amounts of particular metals present
in a sample. Atomic absorption spectroscopy (AAS) makes use of the fact
that specific quantities of energy are required to promote electrons to
higher energy levels.

Ultraviolet and Visible (UV-Visible) spectroscopy utilises the fact that
certain species in solution will absorb particular wavelengths in the
visible and / or ultraviolet regions of the spectrum of electromagnetic
radiation. The amount of light absorbed is directly related to the amount
of the species present in the sample.

Colorimetry makes use of the fact that the concentration of
light-absorbing species in a sample of a coloured solution can be estimated
by comparing the colour of the sample with the colours of solutions of
known concentration. The higher the concentration of Cu(aq) in a solution
of copper sulfate, for example, the more intense will be the blue colour of
the solution. Copper sulfate solutions are blue because Cu ions absorb
wavelengths in the orange-red region of the spectrum.

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