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Chapter 8 and 9 (and a little 10) Atomic Spectroscopy Instrumental Analysis Spring 2011 I. Optical Atomic Spectra • Again, these are going to be line spectra • Why are spectrum of different atoms different? Or atom vs. ion? Atomic Sodium Magnesium (I) ion emission absorbance fluorescence Schematic of absorption, emission and fluorescence by atoms in a flame. A. Atomic Emission Spectra • At room temperature all atoms in a sample are in ground state. B. Atomic Absorption Spectra • Atoms are in hot gaseous medium absorb radiation B. Atomic Fluorescence Spectra • Atoms can be made to fluoresce by irradiating the flame with an source that contains the wavelengths absorbed by the element II. Temperature and Atomic Spectra • Has large effect on number of excited and unexcited atomic particles Example • Calculate the ratio of sodium atoms in the 3p excited states to the number in the ground state at 2500K and 2510K III. Atomization • Converts sample to gaseous atoms or ionized atoms A. Nebulizer B. Flame atomization • In flame atomizer a solution of the sample is nebulized by a flow of gaseous oxidant, mixed with a gaseous fuel and then carried into a flame where atomization occurs. C. Flame • In general: II. Atomic Absorbance Instrumentation A. Radiation Sources 1. Hollow Cathode Lamp IV. Sources of Interferences A. Spectral Interferences: interfering species that give spectral lines that overlap with analyte lines B. Chemical Interference • Matrix ion may form complex • Ionization in flame V. Atomic Emission • Inductively coupled plasma A. Advantages/Disadvantages of ICP