Laser Opto-Acoustic Study of Phase Transitions in Metals
Confined by Transparent Dielectric¹

A. Yu. Ivochkin^a, *, A. G. Kaptilniy^b, A. A. Karabutov^a, and D. M. Ksenofontov^a

^a International Laser Center of M.V. Lomonosov Moscow State University, Leninskie Gori 1-62, Moscow, 119991 Russia

^b Joint Institute for High Temperatures, Russian Academy of Science,
Izhorskaya str., 13/19, Moscow, 125412 Russia

*e-mail: ivochkin@yandex.ru

Received October 26, 2011; in final form, March 7, 2012; published online June 12, 2012

Abstract—First-order phase transitions in metal induced by nanosecond laser pulse are studied here. The metal
surface is irradiated through a layer of transparent dielectric—an optical glass. Such confinement considerably
increases the efficiency of pressure generation at the metal surface. This technique allows to obtain near-critical
states of metals—with temperatures ~10⁴ K and pressures ~10⁴ atm with table-top equipment. At the same time
the glass prevents the ablation plume formation—so the surface temperature can be measured using thermal
radiation data. An experimental setup for simultaneous measurements of pressure, temperature and reflectivity
was assembled based on the elaborated method of experimental research. The processes of melting of lead and
boiling of mercury were studied. The onset of the phase transition process led to a considerable tightening of
the pressure pulse. A substantial drop of surface reflectivity due to increase of temperature and decrease of den-
sity was observed.

DOI: 10.1134/S1054660X12070055

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