  The progress of miniaturisation in integrated electronics has led to atomic
and nanometre-sized dopant devices in silicon. Such structures can be
fabricated routinely by hydrogen resist lithography, using various dopants such
as phosphorous and arsenic. However, the ability to non-destructively obtain
atomic-species-specific images of the final structure, which would be an
indispensable tool for building more complex nano-scale devices, such as
quantum co-processors, remains an unresolved challenge. Here we exploit X-ray
fluorescence to create an element-specific image of As dopants in silicon, with
dopant densities in absolute units and a resolution limited by the beam focal
size (here $\sim1~\mu$m), without affecting the device's low temperature
electronic properties. The As densities provided by the X-ray data are compared
to those derived from Hall effect measurements as well as the standard
non-repeatable, scanning tunnelling microscopy and secondary ion mass
spectroscopy, techniques. Before and after the X-ray experiments, we also
measured the magneto-conductance, dominated by weak localisation, a quantum
interference effect extremely sensitive to sample dimensions and disorder.
Notwithstanding the $1.5\times10^{10}$ Sv ($1.5\times10^{16}$ Rad/cm$^{-2}$)
exposure of the device to X-rays, all transport data were unchanged to within
experimental errors, corresponding to upper bounds of 0.2 Angstroms for the
radiation-induced motion of the typical As atom and 3$\%$ for the loss of
activated, carrier-contributing dopants. With next generation synchrotron
radiation sources and more advanced optics, we foresee that it will be possible
to obtain X-ray images of single dopant atoms within resolved radii of 5 nm.
