  Based on Quasiparticle Interference(QPI) around a point impurity, we
demonstrate an analysis scheme that extracts the lifetime of a quasiparticle by
using the Local Density of States(LDOS) data around the impurity in a Scanning
Tunneling Microscopy(STM) experiment. This data analysis scheme would augment
the Fourier-Transform Scanning Tunneling Spectroscopic method which provides us
with the quasiparticle dispersion. Thus, point impurities can be used as probes
to extract quasiparticle lifetimes from STM experiments and this would
complement other experimental methods such as Angle Resolved Photo-emission
Spectrocopy(ARPES). We detail how the scheme would apply to conventional
metals/Fermi Liquids and Superconductors.
