[R] Isotopic notation in plots

[Barry Rowlingson]

> Try:
> 
>   plot(1:10,xlab=expresssion(""^{14}*C))
> 
> ??

Is there a way of showing atomic number and atomic mass next to the symbol?

This:
plot(1:10,xlab=expression({}[7]^{14}*C))

almost works, but the 7 is adjacent to the invisible {}, instead of 
being right-aligned next to the C.

Slightly closer is:
plot(1:10,xlab=expression(scriptstyle(atop(7,14))*C))

but the 7 and 14 are centre-aligned.

Padding the 7 out with a phantom 0 looks okay though:

expression({}[phantom(0)*7]^{14}*C))

Apologies to chemists if I've got my atomic number and atomic mass the 
wrong way up.

Barry