Onecolumn without page break

Question

How can I make a one column in a two column article, without page breaking???

I am writing an article to submit to NIM. The article should be 2 columns. In one of the pages I need to put a wide figure at the top of the page, and then continue with 2 column text, like in the attached Screenshot_1.png...

But the way I am trying this, latex puts the 2 column continuation to a new page...

Is this possible in Latex without page break?

This is how I try:

\documentclass[12pt]{elsarticle}

\journal{Nucl. Instrum. Methods A}

\begin{document}

\begin{twocolumn}

   bla, bla, bla

\end{twocolumn}

\onecolumn

\begin{figure}[t]

\begin{center}

\includegraphics[width=17.4cm]{pic/RESULTS_SUM.pdf}

\label{Si_Results}

\end{center}

\end{figure}

\begin{twocolumn}

   bla, bla, bla,

\end{twocolumn}

\end{document}

Answer 1

If you want to set the entire text in two column, then give the number of columns in class option, please avoid to keep \begin{twocolumn}..., example given below:

\documentclass[twocolumn,12pt,3p]{elsarticle}
\usepackage{lipsum}
\journal{Nucl. Instrum. Methods A}

\begin{document}

\title{Article title}

\author{Author Name}

\begin{abstract}
\lipsum[1]
\end{abstract}
\maketitle

   bla, bla, bla

\lipsum[1-8]

\begin{figure*}
\centering
\includegraphics[width=17.4cm]{example-image-a}
\label{Si_Results}
\end{figure*}

\lipsum[1-8]

\end{document}

In general, any floats are not allowed in first page of an article...