FIU CHM 4130 - CHAPTER 10_Xiao_AES_2018 (59 pages)

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CHAPTER 10_Xiao_AES_2018



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Chapter 10 Atomic Emission Spectroscopy Using Plasmas Arcs or Sparks 2 VOL 2 NO 1 ISSN THE CHEMICAL EDUCATOR http journals springer ny 430 4171 9 Emission of radia on upon relaxa on from excited S s1 tate 1997 SPRINGER VERLAG NEW YORK INC EXCITED STATE h GROUND STATE Excitation and Atomization Traditionally based on Flame and Electrothermal But Plasma Arc and Spark Why 1 Higher temperature 2 Excitation conditions ICP AES Advantages Increased atomiza on excita on Inductively coupled plasmas are at least 2X as hot as flames or furnaces 6000 10000 K are common Higher temperature to prevent the formation of most interferences break down oxides and eliminate most molecular spectral interferences Wider range of elements Good emission spectra for most elements with same experimental setup can record all at the same time Can determine low concentrations of refractory compounds i e oxides Can determine non metal i e Cl Br I S Wide dynamic range Larger linear range ICP AES Disadvantages Spectra are highly complex increase probability of interferences for quantitative work Need more expensive optical equipment more difficult to maintain What is a Plasma electrically conducting gaseous mixture contains high concentration of cations and electrons zero net charge very high temperatures 10 000 K Types of Plasma Inductively coupled plasma ICP Direct current plasma DCP Microwave induced plasma MIP Inductively coupled plasma ICP ICP source is called a torch Consist of three concentric quartz tubes water cooled induction coil OF AN ICP TORCH Three concentric tubes torch up to 2 5 cm diameter Three gas streams cools outer tube defines plasma shape and delivery sample Tesal coil ionize Ar RF power provide radio frequency RF up to 2 kW ICP torch Schematic of an ICP torch and load coil showing how the inductively coupled plasma is formed Brilliant white core Ar continuum lines Flame like tail up to 2 cm Transparent region measurements made Hotter than flame 10 000K more complete



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