# how to write an equation with a special arrow and super and sub scripts

How do I generate something like this?I don't know how to generate such arrows and how to write above and below the arrow.

Two possible ways, with mathtools and with chemarrow.

The chemarrow spacing is definitely better, but it's necessary to switch again into math mode for the \alpha and \beta ... texts, unless other ways of providing the characters are used.

Another method: stackengine package by Steven B. Segletes.

\documentclass{article}

\usepackage{amssymb}
\usepackage{mathtools}
\usepackage{chemarrow}
\begin{document}

\section{First}

$$:C \underset{\beta(V)}{\xrightleftharpoons{\alpha(V)}} O$$

$$:C\; \autorightleftharpoons{\alpha(V)}{\beta(V)}\quad O$$

$$:C \autorightleftharpoons{\scriptsize\alpha(V)}{\scriptsize\beta(V)} O$$

\end{document}


christian hupfer's answer is good, but there's an even more compact version of his second example, that takes advantage of the optional argument to the \x...harpoons construction to insert the "lower limit".

i think the "default" arrows are too short, so i've forced them to be longer by adding space around the "upper limit". a \quad is too much, so i've specified an amount of space that's just a little over half that.

also, in my opinion, there isn't enough space between the arrows and what they connect, so i've added explicit thick spaces there.

\documentclass{article}

\usepackage{amssymb}
\usepackage{mathtools}

\begin{document}

$$:C \; {\xrightleftharpoons[\beta(V)]{\alpha(V)}} \; O$$

$$:C \; {\xrightleftharpoons[\beta(V)]{\mkern10mu\alpha(V)\mkern10mu}} \; O$$

\end{document}