  We demonstrate that strong impulsive gas heating or heating suppression at
standard temperature and pressure can occur from coherent rotational excitation
or de-excitation of molecular gases using a sequence of non-ionizing laser
pulses. For the case of excitation, subsequent collisional decoherence of the
ensemble leads to gas heating significantly exceeding that from plasma
absorption under the same laser focusing conditions. In both cases, the
macroscopic hydrodynamics of the gas can be finely controlled with ~40 fs
temporal sensitivity.
