  Strong optical forces with minimal spontaneous emission are desired for
molecular deceleration and atom interferometry applications. We report
experimental benchmarking of such a stimulated optical force driven by
ultrafast laser pulses. We apply this technique to accelerate atoms,
demonstrating up to an average of $19$ $\hbar k$ momentum transfers per
spontaneous emission event. This represents more than an order of magnitude
improvement in suppression of spontaneous emission compared to radiative
scattering forces. For molecular beam slowing, this technique is capable of
delivering a many-fold increase in the achievable time-averaged force to
significantly reduce both the slowing distance and detrimental losses to dark
vibrational states.
