  An effect of laser-cooling of water was observed for the first time with a
temperature decrease dT = -2.2 K after irradiation of liquid water surface by a
powerful Ar-Xe pulse laser with a pulse energy of about 1 J and wavelength L =
1.73, 2.63 and 2.65 um. The discovered effect can apparently be ascribed to the
optical excitation of vibrational states of H2O molecules followed by an
endothermic consolidation of chemically active excited molecules into a
quasi-stable cluster-like structure. The measured time dependences of the
cooling effect show that a typical life time of the new state of water amounts
to hours. It has also been shown that the life time of the excited vibrational
molecular states due to a radiation trapping effect can be estimated to at
least hundreds of seconds.
