  We demonstrate that spin-exchange dephasing of Larmor precession at
near-earth-scale fields is effectively eliminated by dressing the alkali-metal
atom spins in a sequence of AC-coupled 2-pi pulses, repeated at the Larmor
precession frequency. The contribution of spin-exchange collisions to the
spectroscopic line width is reduced by a factor of the duty cycle of the
pulses. We experimentally demonstrate resonant transverse pumping in magnetic
fields as high as 0.1 Gauss, present experimental measurements of the
suppressed spin-exchange relaxation, and show enhanced magnetometer response
relative to a light-narrowed scalar magnetometer.
