  Isotope thermometry, widely used to measure the temperature of a hot nuclear
system formed in energetic nuclear collisions, is examined in the light of
S-matrix approach to the nuclear equation of state of disassembled nuclear
matter. Scattering between produced light fragment pairs, hitherto neglected,
is seen to have an important bearing on the extraction of system temperature
and volume at freeze-out from isotope thermometry. Taking due care of the
scattering effects and decay of the primary fragments, a more reliable way to
extract the nuclear thermodynamic parameters is suggested by exploiting
least-squares fit to the observed fragment multiplicities.
