Elemental Analysis using Atomic Absorption and Emission Spectroscopy Bodhisatwa Das

Spectroscopy Fundamentals:Spectroscopy is the use of the absorption, emission, or scattering of electromagnetic radiation by matter to qualitatively or quantitatively study the matter or to study physical processes. The matter can be atoms, molecules, atomic or molecular ions, or solids. The interaction of radiation with matter can cause redirection of the radiation and/or transitions between the energy levels of the atoms or molecules.

Physics behind Spectroscopy• Planck’s equation : λ= hc/(E2- E1)λ = Wavelength h = Planck’s constantE2 & E1 energy levels of electron.

Beer Lambert’s Law:

Law of Diffraction(Bragg’s law):nλ= d sinθn= order of diffractionλ = wavelengthd= distance between slitsθ= angle of diffraction

Principle of Absorption spectroscopy

• Absorbance of photon of specific frequency reveals presence of specific elements.

• When light passed through a sample excites its atoms the specific atoms absorb light of specific wavelength.

• When transmitted light comes out ,the absorbed wavelengths are missing from the spectra. From this the element can be identified.

Steps Involved:• Sample preparation(dissolving in acids/water).• Calibration.• Nebulization.• Atom formation.• Flaming or light passing.• Absorption.• Detection of transmitted light.• Background correction.• Data analysis.

Principle of Emission Spectroscopy:• Emission spectroscopy is a spectroscopic technique which

examines the wavelengths of photons emitted by atoms or molecules during their transition from an excited state to a lower energy state.

• Each element emits a characteristic set of discrete wavelengths according to its electronic structure, by observing these wavelengths the elemental composition of the sample can be determined.

Types

• Flame Emission• Plasma emission• Direct arc

Data Analysis

References:

• Atomic Absorption and Emission Spectroscopy- Ed Metcalfe

• Spectroscopy -B.P Straughan,S.Walker• Practical Absorption Spectroscopy-

A.Knowless,C.Burgress

Thank You!!