  We study the unconventional superconducting correlations caused by a single
isolated magnetic impurity in a conventional s-wave superconductor. Due to the
local breaking of time-reversal symmetry, the impurity induces unconventional
superconductivity which is even in both space and spin variables but odd under
time inversion. We derive an exact proportionality relation between the
even-frequency component of the local electron density of states and the
imaginary part of the odd-frequency local pairing function. By applying this
relation to scanning tunneling microscopy spectra taken on top of magnetic
impurities immersed in a Pb/Si(111) monolayer, we show experimental evidence of
the occurrence of the odd-frequency pairing in these systems and explicitly
extract its superconducting function from the data.
