I really don't get it. I've made e.th. in theory and still it says that I've probably missed "}" somewhere.
\documentclass[a4paper,12pt]{scrartcl}
\usepackage[ngerman]{babel}
\usepackage{bpchem}
\usepackage{times}
\usepackage[version=3]{mhchem}
\usepackage{graphicx}
\usepackage{pdflscape}
\usepackage[final]{pdfpages}
\usepackage{hyperref}
\usepackage{geometry}
\geometry{a4paper, left=25mm, right=20mm, top=2cm, bottom=2cm}
\newcommand{\degreeCelsius}{\ensuremath{\,^{\circ}\mathrm{C}}\xspace}
\begin{document}
\begin{tabular}{ll}
{\footnotesize Single-Photon Polymerization (1-PP):} & {\footnotesize Two-Photon Polymerization (2-PP):} \\
{\footnotesize
\begin{itemize}
\item UV-light irradiation
\item restricted to the surface
\end{itemize}}
&
{\footnotesize
\begin{itemize}
\item NIR-laser irradiation
\item pulses focused into the volume of the resin
\item condition: certain photon density value to be exceeded
\end{itemize}}
\\
\end{tabular}
\end{document}
itemizein anlcolumn, because there won't be line breaks. You need apcolumn. – egreg Jun 26 '13 at 19:19longtableis used, but the problem is just the same. – egreg Jun 26 '13 at 22:37