  We have studied the effects of chirped femtosecond laser pulses on the
formation of ultracold molecules in a Rb magneto-optical trap. We have found
that application of chirped femtosecond pulses suppressed the formation of
85Rb-2 and 87Rb-2 lowest triplet state molecules in contrast to comparable
non-chirped pulses, cw illumination, and background formation rates. Variation
of the amount of chirp indicated that this suppression is coherent in nature,
suggesting that coherent control is likely to be useful for manipulating the
dynamics of ultracold quantum molecular gases.
