H. Švajdlenková

Molecular probe dynamics and free volume in organic glass-formers and their relationships to structural relaxation: 1-propanol.

A joint study of the rotational dynamics and free volume in amorphous 1-propanol (1-PrOH) as a prototypical monohydroxy alcohol by electron spin resonance (ESR) or positron annihilation lifetime spectroscopy (PALS), respectively, is reported. The dynamic parameters of the molecular spin probe 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) and the annihilation ones of the atomic ortho-positronium (o-Ps) probe as a function of temperature are compared. A number of coincidences between various effects in the ESR and PALS responses at the corresponding characteristic ESR and PALS temperatures were found suggesting a common origin of the underlying dynamic processes that were identified using viscosity (VISC) in terms of the two-order parameter (TOP) model and broadband dielectric spectroscopy (BDS) data.

Relationships between Positron Lifetime and Dynamics of Polymers

In this work positron annihilation lifetime spectroscopy (PALS) is employed to study the ortho-Positronium lifetime parameters τ3>, σ3 and I3 in two structurally simple amorphous polymers 1,2-poly(butadiene) and cis-1,4-poly(isoprene). The ortho-Positronium mean lifetime parameter τ3> is compared with dynamics data from broadband dielectric spectroscopy (BDS) and electron spin resonance (ESR) experiments. Coincidences of characteristic temperatures from PALS with BDS and ESR experiments show close relationships between positron lifetime and dynamics of polymers.