Discuss the principles of atomic emission spectroscopy?

Answer 1

Firstly, the sample to be analysed is atomised and mixed with fuel in a nebuliser. It is then combusted providing the molecules and ions to become atoms. A hollow-cathode lamp containing the corresponding metal as in the solution (ie. solution of Cu ions = Cu metal used in lamp) is shone through the flame. With the energy provided by the flame, the atoms become 'excited' absorbing photons of light of a specific wavelength. The wavelength of light is isolated by a monochromator and a photomultiplier is used to magnify the current produced by the light so that it may be detected and processed by a computer. The amount of light absorbed (obtained by: initial light produced by lamp - final light detected) is directly proportional to the amount of cations present in the solution.

Answer 2

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. Emission spectroscopy developed in the late 19th century and efforts in theoretical explanation of atomic emission spectra eventually led to quantum mechanics.

Answer 3

This liquid-solid chromatography is based on the (re) partition of solutes between the adsorbent and fixed mobile liquid phase. Each solute is subjected to a retention force (by adsorption) and a driving force by the mobile phase. The resulting equilibrium leads to a differential migration of the solutes in the sample to be analyzed, which allows their separation.

Adsorption: Adsorption is the attachment of molecules dissolved in the solid phase. This binding is due to the establishment of secondary bonds between the adsorbent surface and the adsorbed molecule: dipole-ion bonding or dipole-dipole or van der Waals bonding.

Adsorbents: These are very divided solid (adsorption is a surface phenomenon), thus 1 g of alumina for chromatography may represent a surface of about 100 m2. we distinguish

Adsorbents low adsorption capacity, such as alumina, talc or sodium carbonate.

Adsorbents strong as silica gel.

Answer 4

Atomic emission spectroscopy involves using a high temperature to excite atoms in a sample, causing them to emit characteristic wavelengths of light. Each element emits a unique set of wavelengths due to electron transitions within the atoms. By measuring the intensity and wavelength of emitted light, a qualitative and quantitative analysis of the elements present in a sample can be performed.