The width of an unresolved transition array, which, was once regarded as in
sensitive to electron temperature by Audebert et al. (Phys. Rev. A 32 (1985
) 409], is found to be a temperature-sensitive function to a certain extent
and has the potential of being used in plasma diagnostics. In this letter,
on the assumption that the plasma has achieved the local thermodynamical e
quilibrium and that each of the subarrays has a Gaussian shape, the electro
n temperature of a gold plasma produced by laser irradiation of a microdot
is obtained by comparing the experimental width with the theoretical width.
The full widths at half maximum of the unresolved transition arrays are co
mputed in the formalism of the spin-orbit-split arrays.