LaTeX: adjust space inside matrix

\documentclass{minimal}
\usepackage{amsmath}
\usepackage{array}
\setlength{\arraycolsep}{10pt}
\setlength{\extrarowheight}{10pt}
\begin{document}
\begin{equation}
\left[ \begin{matrix}
a & b & c \d & e & f \g & h & i
\end{matrix} \right]
\end{equation}
\end{document}