A simple method for the generation of negative pressure in liquids

A new technique for the generation of negative pressure in liquids is described, based on the pressure difference that exists across a curved liquid-vapour interface. Menisci in pores having very small radii may induce large negative pressures, or tensions, within the liquid phase. The magnitude of this tension is readily controlled through the pressure of the external vapour phase. Liquid butane when contained in hollow capsules, or Bertholet tubes, with walls formed from Vycor porous glass (pore radius ca. 5 nm) has developed negative pressures as large as -4 MPa for brief periods and lesser tensions for much longer times This tension approaches the theoretical limit (ca. -6 MPa) calculated from the Laplace equation. Maximum possible tensions based on the theory of homogenous nucleation and on spinodal decomposition are much larger and, in principle, may be reached by reducing the pore size. Our unsuccessful attempts to do so are described.