<html>
<head>
<meta content="text/html; charset=windows-1252"
http-equiv="Content-Type">
</head>
<body bgcolor="#FFFFFF" text="#000000">
<div class="moz-cite-prefix">Absorption coefficient can be used to
make Tauc plot and tangent method gives Tauc gap [
<a class="moz-txt-link-freetext" href="https://en.wikipedia.org/wiki/Tauc_plot">https://en.wikipedia.org/wiki/Tauc_plot</a> ].<br>
<br>
Optical gap is determined from the plot of epsilon2 (the imaginary
part of the dielectric function) using the tangent method.<br>
<br>
To visualize what Xavier describes in the posts at <br>
<br>
<a class="moz-txt-link-freetext" href="https://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/msg08951.html">https://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/msg08951.html</a><br>
<br>
see for example Figure 7 in the article titled "Band Gap
Determination from Diffuse Reflectance Measurements of Irradiated
Lead Borate Glass System Doped with TiO2 by Using Diffuse
Reflectance Technique" by S. Ebraheem and A. El-Saied [
<a class="moz-txt-link-freetext" href="http://file.scirp.org/Html/8-7701026_31475.htm">http://file.scirp.org/Html/8-7701026_31475.htm</a> ]. This article
also describes how r might be determined for the Tauc plot.<br>
<br>
On 3/7/2016 3:05 PM, said chibani wrote:<br>
</div>
<blockquote
cite="mid:CAPN4NeEw0BM5oUHbx+snhSRP16UbmYPmL=7kV2tL3V0Q_Vv5iQ@mail.gmail.com"
type="cite">
<div dir="ltr"><span
style="font-size:16px;background-color:rgb(245,245,245)"><span
style="font-size:12.8px;background-color:rgb(255,255,255)">Dear
Wien Users ,</span><br>
how to determine</span><span
style="font-size:16px;background-color:rgb(245,245,245)"> </span><span
style="font-size:16px;background-color:rgb(245,245,245)">optical
gap</span><span
style="font-size:16px;background-color:rgb(245,245,245)"> </span><span
style="font-size:16px;background-color:rgb(245,245,245)">from</span><span
style="font-size:16px;background-color:rgb(245,245,245)"> </span><span
style="font-size:16px;background-color:rgb(245,245,245)">the
graph of </span><span
style="font-size:16px;background-color:rgb(245,245,245)"> </span><span
style="font-size:16px;background-color:rgb(245,245,245)">optical</span><span
style="font-size:16px;background-color:rgb(245,245,245)"> </span><span
style="font-size:16px;background-color:rgb(245,245,245)">properties</span><span
style="font-size:16px;background-color:rgb(245,245,245)"> ? is
determine from the graph of </span><span
style="font-size:16px">absorption coefficient? and how ?</span><br>
</div>
</blockquote>
</body>
</html>