[Tex/LaTex] Vspace in a table in a two column page

tablesvertical alignment

I made a table spanning the top of a two column page, but there is a problem in the last column where $j$ is very close to the hline above, while other elements in the same row are of the same vertical height. The same problem happens to the "transition" header in the last column. And is there a way to make the first row a little wider(the row with $\lambda$ and transition)? How to fix these issues?

\newcolumntype{M}{>{\centering\arraybackslash}m{\dimexpr.096\linewidth-2\tabcolsep}}

  \begin{table*}[t!]
    \footnotesize
    \centering
    \begin{tabular}{|| M | M || M | M || M | M || M | M || M | M ||}
    \multicolumn{2}{c}{\bf Lyman} & \multicolumn{2}{c}{\bf Balmer} & \multicolumn{2}{c}{\bf Paschen} & \multicolumn{2}{c}{\bf Brackett} & \multicolumn{2}{c}{\bf Pfund} \\
    \hline
    $\lambda$(nm) & transition & $\lambda$(nm) & transition & $\lambda$(nm) & transition & $\lambda$(nm) & transition & $\lambda$(nm) & transition \\[1mm]
    \hline
    93.78 & 6$\rightarrow$1 & 410.2 & 6$\rightarrow$2 & 1094 & 6$\rightarrow$3 & 2630 & 6$\rightarrow$4 & 7400 & 6$\rightarrow$5 \\[1mm]
    94.98 & 5$\rightarrow$1 & 434.0 & 5$\rightarrow$2 & 1282 & 5$\rightarrow$3 & 4050 & 5$\rightarrow$4 &  & \\[1mm]
    97.25 & 4$\rightarrow$1 & 486.1 & 4$\rightarrow$2 & 1875 & 4$\rightarrow$3 &  &  &  & \\[1mm]
    102.6 & 3$\rightarrow$1 & 656.3 & 3$\rightarrow$2 &  &  &  &  &  & \\[1mm]
    121.6 & 2$\rightarrow$1 &  &  &  &  &  &  &  & \\[1mm]
    \hline
    $\frac{\lambda_{1,j}}{\lambda_{1,j+1}}$ & $j$ & $\frac{\lambda_{2,j}}{\lambda_{2,j+1}}$ & $j$ & $\frac{\lambda_{3,j}}{\lambda_{3,j+1}}$ & $j$ & $\frac{\lambda_{4,j}}{\lambda_{4,j+1}}$ & $j$ & $\frac{\lambda_{5,j}}{\lambda_{5,j+1}}$ & $j$ \\[4mm]
    \hline
    1.01 & 5 & 1.05 & 5 & 1.17 & 5 & 1.54 & 5 &  & \\[1mm]
    1.02 & 4 & 1.12 & 4 & 1.46 & 4 &  &  &  & \\[1mm]
    1.05 & 3 & 1.35 & 3 &  &  &  &  &  & \\[1mm]
    1.18 & 2 &  &  &  &  &  &  &  & \\[1mm]
    \hline
    \end{tabular}
    \caption{Expected hydrogen wavelengths, transitions and wavelength ratios.} 
    \end{table*}

Here is the preamble.
\documentclass[aps,prl,reprint,twocolumn,secnumarabic,nobalancelastpage,amsmath,amssymb,nofootinbib]{revtex4}

        % nofootinbib is another document class option that allows you to put
        % footnotes on the page where they occur rather than at the end of the
        % paper.  This makes for easier reading!

        % secnumarabic is a particularly nice way of identifying sections by
        % number to aid electronic review and commentary.

        % amsmath and amssymb are necessary for the subequations environment
        % among others

        \usepackage{graphics}      % standard graphics specifications
        \usepackage{graphicx}      % alternative graphics specifications
        \usepackage{longtable}     % helps with long table options
        \usepackage{url}           % for on-line citations
        \usepackage{bm}            % special 'bold-math' package
        \usepackage{comment}
        \usepackage{fancyhdr}% http://ctan.org/pkg/{fancyhdr,graphicx,lastpage}
        \usepackage{color} 
        \usepackage{atbegshi}
        \usepackage{textcomp}
        \usepackage{siunitx}
        \usepackage{lipsum}
        \usepackage{float}
        \usepackage{array}
        \usepackage{tabularx}   % for 'tabularx' environment
        \newcolumntype{C}{>{\centering\arraybackslash}X}
        \usepackage{booktabs}   % for '\toprule', '\midrule', etc
        \usepackage{amsmath}    % for '\dfrac' macro 




        \newcommand \widebox [1]{\setlength\fboxsep{6pt} \boxed { #1}}
        \newcommand \ev [1]{\left\langle #1 \right\rangle}
        \newcommand \evd {\operatorname{E}\evdel}
        \newcommand \bbrac [1] {\left ( #1 \right)}
        \newcommand \bl {\biggr | }
        \newcommand \espa {\\[2.5 mm]}
        \newcommand \vbrac [1] {\left [ \,#1 \,\right]}
        \newcommand \dpart [2] {\frac{\partial{#1}}{\partial{#2}}}
        \newcommand \kai [2] {\chi_{#1}^{\, (#2)}}
        \newcommand \ud {\uparrow \,\downarrow}
        \newcommand \du {\downarrow\,\uparrow }

        \fancyhf{}
        \pagestyle{fancy}
        \chead{MODERN \,\,\,PHYSICS\,\,\, LABOTORARY \\[-0.9em]} 
        \lhead{PHYSICS \textbf{18L}   \\[-1.1em]}
        \rhead{23 APRIL 2015 \\[-1.1em]}
        \cfoot{\thepage}
        \AtBeginDocument{%
          \rfoot{\raisebox{1.5pt}{\scalebox{0.7}{\textcopyright}} 2015  Physics Department}%
          \AtBeginShipoutNext{%
            \rfoot{}%
          }%
        }
        \renewcommand{\headrulewidth}{1pt}

enter image description here

Best Answer

I wouldn't use the m column type for this table. In its place, I would use a centered form of the X column provide (provided by the tabularx package), in part to let LaTeX handle the chores of determining column widths. Separately, I'd use the line-drawing macros of the booktabs package to get well-spaced horizontal lines; plus, I'd omit all vertical lines.

The only "tricky" aspect of the table is that whereas the contents of most cells should be centered, the contents of the first 5 data rows of the first column would benefit from being aligned on the decimal separator. This may be achieved by (i) using the S column type (provided by the siunitx package) for the first column and (ii) encasing those items in the first column that should be centered in pairs of curly braces.

Finally, rather than add 1 mm of extra row height manually to each row, I believe it's easier to set the macro \extrarowheight to that value.

enter image description here

\documentclass[twocolumn]{article}
\usepackage{tabularx}   % for 'tabularx' environment
\newcolumntype{C}{>{\centering\arraybackslash}X}
\usepackage{booktabs}   % for '\toprule', '\midrule', etc
\usepackage{amsmath}    % for '\dfrac' macro 
\usepackage{siunitx}    % for "S" column type

\begin{document}
\begin{table*}
   \setlength\tabcolsep{2pt}  % default value: 6pt
   \setlength\extrarowheight{1mm}
   \small
    \begin{tabularx}{\textwidth}{@{} S[table-format=3.2] *{9}{C} @{}}
    \toprule
    \multicolumn{2}{@{}c}{\bfseries Lyman} &
    \multicolumn{2}{c}{\bfseries Balmer} &
    \multicolumn{2}{c}{\bfseries Paschen} &
    \multicolumn{2}{c}{\bfseries Brackett} &
    \multicolumn{2}{c@{}}{\bfseries Pfund} \\
    \cmidrule(r){1-2} \cmidrule(lr){3-4} \cmidrule(lr){5-6}
        \cmidrule(lr){7-8} \cmidrule(l){9-10}
    \multicolumn{1}{C}{$\lambda$ (nm)} & transition &
    $\lambda$ (nm) & transition & $\lambda$ (nm) & transition &
    $\lambda$ (nm) & transition & $\lambda$ (nm) & transition \\
    \midrule
    93.78 & 6$\to$1 & 410.2 & 6$\to$2 & 1094 & 6$\to$3 & 2630 & 6$\to$4 & 7400 & 6$\to$5 \\
    94.98 & 5$\to$1 & 434.0 & 5$\to$2 & 1282 & 5$\to$3 & 4050 & 5$\to$4 \\
    97.25 & 4$\to$1 & 486.1 & 4$\to$2 & 1875 & 4$\to$3 \\
    102.6 & 3$\to$1 & 656.3 & 3$\to$2  \\
    121.6 & 2$\to$1 \\
    \midrule
     {$\dfrac{\lambda_{1,j}}{\lambda_{1,j+1}}$} & $j$ &
      $\dfrac{\lambda_{2,j}}{\lambda_{2,j+1}}$  & $j$ &
      $\dfrac{\lambda_{3,j}}{\lambda_{3,j+1}}$  & $j$ &
      $\dfrac{\lambda_{4,j}}{\lambda_{4,j+1}}$  & $j$ &
      $\dfrac{\lambda_{5,j}}{\lambda_{5,j+1}}$  & $j$ \\
    \cmidrule(r){1-2} \cmidrule(lr){3-4} \cmidrule(lr){5-6}
        \cmidrule(lr){7-8} \cmidrule(l){9-10}
    {1.01} & 5 & 1.05 & 5 & 1.17 & 5 & 1.54 & 5 \\
    {1.02} & 4 & 1.12 & 4 & 1.46 & 4 \\
    {1.05} & 3 & 1.35 & 3  \\
    {1.18} & 2 \\
    \bottomrule
    \end{tabularx}
    \caption{Expected hydrogen wavelengths, transitions and wavelength ratios.}
\end{table*}
\end{document}

Addendum The OP has informed me that he/she is using the revtex4 document class, which appears to be incompatible with the booktabs package and its rule-drawing macros. :-(

Here's an alternative solution, which works with the revtex4 document class as well as with many other document classes. It uses a tabular* environment instead of a tabularx environment, and it inserts (typographic) struts at selected locations to obtain a better vertical separation between the lines drawn by \hline and \cline and the material above and below the lines.

I still wouldn't use any vertical lines with this solution, by the way.

enter image description here

\documentclass{revtex4}
%% define a few struts
%% (from code by Claudio Beccari in TeX and TUG News, Vol. 2, 1993)
\newcommand\Tstrut{\rule{0pt}{2.9ex}}       % "top" strut
\newcommand\Bstrut{\rule[-1.2ex]{0pt}{0pt}} % "bottom" strut
\newcommand\TBstrut{\Tstrut\Bstrut}         % "top and bottom" strut

\usepackage{array}      % for '\extrarowheight' macro
\usepackage{amsmath}    % for '\dfrac' macro
\usepackage{siunitx}    % for "S" column type

\begin{document}
\begin{table*}
   \setlength\tabcolsep{0pt}  % default value: 6pt
   \setlength\extrarowheight{1mm}
    \begin{tabular*}{\textwidth}{ S[table-format=3.2] @{\extracolsep{\fill}} *{9}{c} }
    \hline
    \multicolumn{2}{c}{\bfseries Lyman\TBstrut} &
    \multicolumn{2}{c}{\bfseries Balmer} &
    \multicolumn{2}{c}{\bfseries Paschen} &
    \multicolumn{2}{c}{\bfseries Brackett} &
    \multicolumn{2}{c}{\bfseries Pfund} \\
    \cline{1-2} \cline{3-4} \cline{5-6} \cline{7-8} \cline{9-10}
    {$\lambda$ (nm)\TBstrut} & transition &
    $\lambda$ (nm) & transition & $\lambda$ (nm) & transition &
    $\lambda$ (nm) & transition & $\lambda$ (nm) & transition \\
    \hline
    93.78 \Tstrut& 6$\to$1 & 410.2 & 6$\to$2 & 1094 & 6$\to$3 & 2630 & 6$\to$4 & 7400 & 6$\to$5 \\
    94.98 & 5$\to$1 & 434.0 & 5$\to$2 & 1282 & 5$\to$3 & 4050 & 5$\to$4 \\
    97.25 & 4$\to$1 & 486.1 & 4$\to$2 & 1875 & 4$\to$3 \\
    102.6 & 3$\to$1 & 656.3 & 3$\to$2  \\
    121.6 \Bstrut & 2$\to$1 \\
    \hline
     {$\dfrac{\lambda_{1,j}\Tstrut}{\lambda_{1,j+1}\Bstrut}$} & $j$ &
      $\dfrac{\lambda_{2,j}}{\lambda_{2,j+1}}$ & $j$ &
      $\dfrac{\lambda_{3,j}}{\lambda_{3,j+1}}$ & $j$ &
      $\dfrac{\lambda_{4,j}}{\lambda_{4,j+1}}$ & $j$ &
      $\dfrac{\lambda_{5,j}}{\lambda_{5,j+1}}$ & $j$ \\
    \cline{1-2} \cline{3-4} \cline{5-6} \cline{7-8} \cline{9-10}
    {1.01\Tstrut} & 5 & 1.05 & 5 & 1.17 & 5 & 1.54 & 5 \\
    {1.02} & 4 & 1.12 & 4 & 1.46 & 4 \\
    {1.05} & 3 & 1.35 & 3  \\
    {1.18\Bstrut} & 2 \\
    \hline
    \end{tabular*}
    \caption{Expected hydrogen wavelengths, transitions and wavelength ratios.}
\end{table*}
\end{document}