The wavelength at the size of a watermolecule in the range of Exahertz x-ray rather implies very precise laser pulses because the focal point is proportional to the wavelength. It is also relevant for energy transfer into molecules at resonant frequencies.

from the last paragraph linked above:

> For example, attosecond pulses can be used to push molecules, which emit a measurable signal. The signal from the molecules has a special structure, a type of fingerprint that reveals what molecule it is, and the possible applications of this include medical diagnostics.

Basically it's a more precise higher energy X-Ray laser.

I believe the fast turning on and off is a byproduct of a basic method (high-harmonic generation). They do stress the importance of short pulses, but this again may have to do with decoherence of the focal point and not so much the speed of electrons inside the molecule, which is only a model (i.e. relativistic) and remains to be investigated with this new method.