Optical trapping of dielectric particles by a single-beam gradient force trap was demonstrated for the first reported time. This confirms the concept of negative light pressure due to the gradient force. Trapping was observed over the entire range of particle size from 10 um to-25 nm in water. Use of the new trap extends the size range of macroscopic particles accessible to optical trapping and manipulation well into the Rayleigh size regime. Application of this trapping principle to atom trapping is considered. We report the first experimental observation to our knowledge of a single-beam gradient force radiation

We report the viscous confinement and cooling of neutral sodium atoms in three dimensions via the radiation pressure of counterpropagating laser beams. These atoms have a density of about -10 cm and a temperature of -240 p, K corresponding to a rms velocity of -60 cm/sec. This temperature is approximately the quantum limit for this atomic transition. The decay time for half the atoms to escape a -0.2-cm confinement volume is -0.1 sec.

%e report the f~rst observation of optically trapped atoms. Sodium atoms cooled belo~10 3 K in "optical molasses" are captured by a dipole-force optical trap created by a single, strongly focused, Gaussian laser beam tuned several hundred gigahertz below& the Di resonance transition. %e estimate that about 500 atoms are confined in a volume of about 10 p, m at a density of 10"-10" cm 3. Trap lifetimes are limited by background pressure to several seconds. The observed trapping behavior is in good quantitative agreement~ith theoretical expectations.

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We have observed that two-body collisions between cold sodium atoms confined within a magnetic-molasses optical trap lead to significant atomic-density-dependent trap losses. Such losses set an upper limit to the product of atomic density and confinement time that can be achieved in such a trap.