\Shortstack - Why it produces one line in Scriptsize

Question

\documentclass[fleqn,12pt,a4paper]{article}
\usepackage{amstext, amsmath}

\begin{document}
\[
  \alpha \xrightarrow[\stackrel{Alpha}{\shortstack[c]{\text{is Reactant}\\ \text{converting  to}}}]
                     {\stackrel{Beta}{\shortstack[c]{\text{is a product }\\ \text{of reaction}}}}
  \beta
\]
\end{document}

I have no clue why the first line in \stackrel is showing in scriptsize. How to get all the three lines to same fontsizes? I am doing this to get three lines over the arrow. Is there a different and easy way to produce 3 lines over and below the arrow?

Thanks for your help.

Answer 1

There's no need to use \stackrel; you can just put 3 lines into your \shortstack. Moreover, you don't need the c option in \shortstack as this is the default, and you don't need the \text command. So this works:

\documentclass[fleqn,12pt,a4paper]{article}
\usepackage{amstext, amsmath}

\begin{document}
\[
  \alpha \xrightarrow[\shortstack{Alpha\\ is Reactant\\ converting  to}]
                     {\shortstack{Beta\\ is a product\\ of reaction}}
  \beta
\]
\end{document}

However, I don't know how you want your "Alpha" and "Beta" formatted. In my solution, they just appear as normal text.

Answer 2

that is the default behaviour of \stackrel. use a tabular instead, if you have more than two lines.

\documentclass[fleqn,12pt,a4paper]{article}
\usepackage{amstext, amsmath}

\begin{document}
\[
  \alpha \xrightarrow[\tabular{c}Alpha\\is Reactant\\ converting  to\endtabular]
                     {\tabular{c}Beta\\is a product\\ of reaction\endtabular}
  \beta
\]
\end{document}