Producing isolated accents
There's no need to go in math mode:
\`{} \'{} \^{} \~{} \v{} \u{} \.{}
are various examples: just tell TeX to put the accent over nothing.
You can generate the accent like you would normally, only use a space as the letter to apply it to. As an example, consider the following:
\documentclass{article}
\begin{document}
$\tilde{ }$ $\hat{ }$ \'{ }
\end{document}
Which looks like this: