  We demonstrate a novel method for measuring the discrete energy spectrum of a
quantum dot connected very weakly to a single lead. A train of voltage pulses
applied to a metal gate induces tunneling of electrons between the quantum dot
and a reservoir. The effective tunnel rate depends on the number and nature of
the energy levels in the dot made accessible by the pulse. Measurement of the
charge dynamics thus reveals the energy spectrum of the dot, as demonstrated
for a dot in the few-electron regime.
