Photoelectron spectroscopy as a probe for studying phase-transition kinetics

Photoelectron spectroscopy (PES) can be profitably employed for studying three-dimensional phase-transition kinetics as long as the problem of finite escape depth and the presence of the surface is correctly taken into account. A general solution of this problem is presented for transformations following the JohnsonMehl-Avrami-Kolmogorov kinetics. The cases of simultaneous and constant nucleation rates are discussed. We found that the simple relationship between the PES signal I(t) and the untransformed phase X(t):I(t)=l(0)X(t)(1/2) an excellent approximation for the simultaneous nucleation and turns out to be quite good Is for the constant nucleation case.