Atomic absorption spectroscopy is the use of principles ofatomic absorption of light to determine how much of a metallicelement is in a sample. It works by using a few principles whichare faily simple and easy to understand on their own and are thencombined to make the machine and cause it to work. Let's have aquick look. When we burn something, we can, if we burn it hotenough, break it down into atoms. As metal atoms are burned, we'regoing to excite them. That is, we're going to excite theiroutermost electrons and push them to higher energy levels. Notethat there are a couple of quantum mechanical rules that anelectron must follow. First, it will only jump to a specific higherenergy level. A higher level always exists, but what that means isthat there are no "half-levels" or "sorta close" situations. Andthe jump represents a specific quantity of energy. Also, thatelectron must get exactly the right quantity (get it? quantity?quantum?) of energy in a packet to make the jump. That means thatif it doesn't get enough, it doesn't make a "half-jump" and if itgets too much, it will reject the packet of energy. The transitionwill only occur with the absorption of the exact quantity of energyneeded to make that specific transition. Good? Let's jump. We burnour sample in a flame or furnace. Then we shine a special lightthrough it. This special light is for a specific metal. It emitsphotons of just the right energy necessary for the valenceelectrons to make that jump to the next energy level. (That's the"level thingie" we just talked about.) It's a setup, 'cause wepicked our light source to have just the right energy of light forthis metal. So with the light shining and the sample burning, welook at the light coming out the other side of the flame. Therewon't be as much light coming out as went in, because some of thevalence electrons in our sample absorbed some of the light andmoved out to the next energy level for a moment. The more atoms ofthat metal we're looking for that are in our sample, the more lightphotons there are that "won't make it" through the flame. They gotabsorbed by valence electrons. With it so far? Good. One more thingand we're good. We can look at the amount of light coming throughthe flame before we burn our sample to "calibrate" the unit. Thenwe burn our sample and look at the amount of light coming throughthe flame. The more light that doesn't make it, the more that hadto have been absorbed by the metal (specifically its valenceelectrons) in our sample. And that would mean that there was "more"of the metal in our sample. We can actually quantify (tell howmuch) metal was in our sample by this method, which we call atomicabsorption spectroscopy. You got a couple of links if you wantthem. At least look at the drawing and the cool pics in the firstlink. It should lock things in for ya.