siunitx - How can I typeset (-1/2)?

Question

I'm trying to typeset the unit Å^(-1) eV^(-½) with siunitx, using \sisetup{locale=DE} (I don't think this makes any difference here).

Thanks to this question, I have been able to figure out how to typeset roots, but this

\si{\per\angstrom\per\ensuremath{\sqrt{\text{\electronvolt}}}}    

doesn't give me the desired result. (Neither does

\si[per-mode=fraction]{\per\angstrom\per\ensuremath{\sqrt{\text{\electronvolt}}}}

As a matter of fact, both lines yield exactly the same output.)

My theory is that the \ensuremath somehow overwrites the rules for \per.

Is there a more elegant way than

\si{\angstrom^{-1}\electronvolt^{-1/2}

to achieve the exponential expression of this unit?

Any help and/or comments are greatly appreciated.

Answer 1

The moment you use anything that's not strictly a unit macro, siunitx uses 'literal' mode so just typesets your input. You seem to want

\documentclass{article}
\usepackage{siunitx}
\begin{document}
\si{\per\angstrom\per\electronvolt\tothe{1/2}}
\end{document}