<html><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><div><p style="margin: 0.0px 0.0px 0.0px 0.0px"><font face="Arial" size="2" style="font: 10.0px Arial"><span class="Apple-converted-space"><font class="Apple-style-span" face="Helvetica" size="3"><span class="Apple-style-span" style="font-size: 12px;">Dear BoKang,</span></font></span></font></p><p style="margin: 0.0px 0.0px 0.0px 0.0px"><br class="webkit-block-placeholder"></p><p style="margin: 0.0px 0.0px 0.0px 0.0px">Here is my slight & probably incomplete answer (I am not sure how much you already know):</p><p style="margin: 0.0px 0.0px 0.0px 0.0px"><br></p><p style="margin: 0.0px 0.0px 0.0px 0.0px">XAS and EELS give very similar experimental spectra, and are based on similar physical processes, but not exactly the same.</p><p style="margin: 0.0px 0.0px 0.0px 0.0px">In XAS, a photon is absorbed by the sample and, in transmission experiments, the resulting attenuation of the beam is measured while the photon energy is scanned (~ 0.2 - 40 keV depending on the beamline). In EELS in a TEM, the electron beam is held at one energy (e.g. ~ 300 kV) and as electrons pass through the sample, energy is lost. That energy loss is measured in Electron Energy Loss Spectroscopy (detection of ~ 0 - 2000 eV).</p><p style="margin: 0.0px 0.0px 0.0px 0.0px">ELNES is a sub-set of EELS - the Energy Loss Near-Edge Structure, typically the part of the EEL spectrum < 50 eV beyond the edge onset. The setup of the TEM can affect the EELS results, which is why there are adjustable parameters in the w2web TELNES window. </p><p style="margin: 0.0px 0.0px 0.0px 0.0px">My impression is that in XAS the allowed electronic transitions are more strictly governed by the dipole selection rules, whereas in EELS, the rules can be bent a bit more depending on the experiment. However, I have not found a lot in literature that contrasts these two techniques - a lot of people just acknowledge that they are "basically the same."</p><p style="margin: 0.0px 0.0px 0.0px 0.0px">In the end, I guess your question relates to simulating XAS or EELS with Wien2k. I am not sure how the results differ between the two tasks, myself, but would be interested in the answer.</p><p style="margin: 0.0px 0.0px 0.0px 0.0px"><br class="webkit-block-placeholder"></p><p style="margin: 0.0px 0.0px 0.0px 0.0px">Hope this helps a little,</p><p style="margin: 0.0px 0.0px 0.0px 0.0px">Ashley</p><p style="margin: 0.0px 0.0px 0.0px 0.0px"><font class="Apple-style-span" face="Arial" size="2"><span class="Apple-style-span" style="font-size: 10px;"><br class="webkit-block-placeholder"></span></font></p><p style="margin: 0.0px 0.0px 0.0px 0.0px"><font face="Arial" size="2" style="font: 10.0px Arial"><span class="Apple-converted-space"> </span></font></p> <p style="margin: 0.0px 0.0px 0.0px 0.0px"><font face="Arial" size="2" style="font: 10.0px Arial">~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~</font></p> </div><br><div><div>On Dec 4, 2007, at 2:05 PM, 波 康 wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><div>Dear wien users,</div> <div> </div> <div> Using WIEN2k code, we can calculate XAS and ELNES. I am very confused, what's the differences among XAS, ELNES and EELS. Could anyone tell me?</div> <div> </div> <div> Any reply will be appreciated!</div> <div> </div> <div> BoKang</div> <div> </div> <div> </div><div> <br class="khtml-block-placeholder"></div><hr size="1"><a href="http://cn.mail.yahoo.com/promo/carnival07/index.html?source=xy" target="blank">进入雅虎游戏嘉年华，赢取液晶显示器！</a><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">_______________________________________________</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">Wien mailing list</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><a href="mailto:Wien@zeus.theochem.tuwien.ac.at">Wien@zeus.theochem.tuwien.ac.at</a></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><a href="http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien">http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien</a></div> </blockquote></div><br></body></html>