A new ultrafast technique, using high-energy electrons coupled to a laser pump, revealed insights into atomic vibrational dynamics in a laser-heated gold thin film. This technique directly measured the phonon spectrum (quantized packets of energy related to atomic lattice vibrations) and explored the energy transfer from the laser excited electrons to atomic vibrations of the atomic lattice. This work demonstrates that specialized ultra-fast electron diffraction instruments can add to the suite of time-resolved laser pump/probe techniques capable of exploring excitations in materials.