Extending arrows with overset text

Question

I'd like to extend an arrow to allow better readability of characters which are overset using \overset{}{}.

Right now I have

 \overset{k_1}{\rightleftharpoons}

which produces:

and this leaves the subscript awfully close the to harpoon arrow. Thus, is there anyway to just extend the character length?

Answer 1

There are several packages supporting extensible arrows:

• amsmath (\xleftarrow etc., new commands could be similarly created)

• extarrows

• extpfeil

• mathtools

An example suitable for your formula, also demonstrating the optional argument for text under the arrows:

\documentclass{article}
\usepackage{mathtools}
\begin{document}
\[ \xrightleftharpoons[k_2]{\,k_1\,} \]
\end{document}

Output: