Question

Three major spectroscopic methods for elemental analysis atoms are Atomic Absorption Spectroscopy, Atomic Emission Spectroscopy, and Atomic Mass Spectroscopy. Describe 3-4 major parts of the experimental setup for each of the three methods.

Answer 1

Atomic spectroscopy is the technique for determining the elemental composition o a n analyte by its electromagnetic or mass spectrum. There are three widely accepted analytical methods.

1. Atomic absorption spectrometry
2. Atomic emission spectrometry
3. Atomic mass spectrometry

Atomic absorption spectrometry is a very common technique for detecting metals and metalloids in samples. It also measures the concentration of metals in the sample. Basic principle is that the free atoms generated in an atomizer can absorb radiation at specific frequency. The instrument contains Howllow cathode lamp, monochromator, detector, nebulizer and atomizer. Common radiation source in AAS is hollow cathode lamp. Nebulizer sucks up liquid samples at controlled rate. Elements are analyzed in atomizer. Atomization is done by exposing the analyte to high temperatures in a flame or graphite furnace. Monochromator is used to select the specific wavelength of light absorbed by the sample and exclude other wavelengths. The selection of specific light allows the determination of the selected element in the presence of others. The light selected by the monochromator is directed onto a detector. Here the detector converts the light signal into an electrical signal proportional to the light intensity. The processing of electrical signal is fulfilled by a signal amplifier. Finally by the calibration curve determines the unknown concentration of an element in a solution.

Atomic emission spectrometry measures the intensity of emitted radiation. Basic principle of AES is that the electrons of an atom moves from higher energy level to lower energy level and they emit extra amount of energy in the form of light which consists of photons. The instrument comprises on source, atomizer, monochromator and detector. Atomizer analyses elements in their atomic state. Monochromator is used to transmit narrow band of wavelength which is chosen from wavelength of wider range available. Element is detected by detector.

Atomic mass spectrometry is an analytical technique that measures the mass to charge particles. The method is used for determining masses particles, or determining the elemental composition of a sample or molecule. The instrument comprises on, ion source, analyzer and detector. Ion source produces gaseous ions from the substance. Analyzer resolves the ions into their characteristics mass components according to their mass to charge ratio. Detector is used to detect the ions and record the relative abundance of each of the resolved ionic species and converts the ions into electrical signals.