The motion and dimension of molecular nuclear wave packets produced by an ultrashort laser pulse are measured by Coulomb explosion induced by a delayed intense fs laser pulse. Two different continuum wave packets in ${\mathrm{I}}_2$ are observed as they move from an internuclear separation of $\sim 7$ to $>100\mathrm{}$ Å. The ultimate spatial resolution is limited by the pulse duration of the probe laser. For 485 nm excitation of $B$-state wave packets the resolution limit is $\sim 0.5$ Å.

• Received 22 December 1994

DOI:https://doi.org/10.1103/PhysRevLett.74.3780