  Water can be vitrified if it is cooled at rates exceeding $3*10^5$ K/s. This
makes it possible to outrun crystallization in so-called no man's land, a range
of deeply supercooled temperatures where water crystallizes rapidly. One would
naively assume that the process can simply be reversed by heating the resulting
amorphous ice at a similar rate. We demonstrate that this is not the case. When
amorphous ice samples are flash melted with a microsecond laser pulse,
time-resolved electron diffraction reveals that the sample transiently
crystallizes despite a heating rate of more than $5*10^6$ K/s, demonstrating
that the critical heating rate for outrunning crystallization is significantly
higher than the critical cooling rate during vitrification. Moreover, we
observe different crystallization kinetics for amorphous solid water (ASW) and
hyperquenched glassy water (HGW), which suggests that the supercooled liquids
formed during laser heating transiently retain distinct non-equilibrium
structures that are associated with different nucleation rates. These
experiments open up new avenues for elucidating the crystallization mechanism
of water and studying its dynamics in no man's land. They also add important
mechanistic details to the laser melting and revitrification process that is
integral to the emerging field of microsecond time-resolved cryo-electron
microscopy.
