  Vapor deposition of molecules on a substrate often results in glassy
materials of high kinetic stability and low enthalpy. The extraordinary
properties of such glasses are attributed to high rates of surface diffusion
during sample deposition, which makes it possible for constituents to find a
configuration of much lower energy on a typical laboratory time scale1,2,7. The
exact structure of the resulting phase is often assumed to be identical to that
obtained by aging of ordinary glass over exceedingly long times. Using Fast
Scanning Calorimetry technique, we show that out-of-equilibrium relaxation
kinetics and possibly the enthalpy of vapor-deposited films of toluene, an
archetypical fragile glass former, are distinct from those of ordinary
supercooled phase even when the deposition takes place at temperatures above
the glass softening. These observations provide support to the conjecture that
the vapor-deposition may result in formation of non-crystalline phase of unique
structural, thermodynamic, and kinetic properties.
