Neutron reflectivity measurements of the translational motionof tris(naphthylbenzene) at the glass transition temperature

• Published in: The Journal of chemical physics 2006-05, Vol.124 (18), p.184501-184501-9
• Main Authors: Swallen, Stephen F., Mapes, Marie K., Kim, Yong Seol, McMahon, Robert J., Ediger, M. D., Satija, Sushil
• Format: Article
• ISSN: 0021-9606; 1089-7690
• DOI: 10.1063/1.2191492

The translational dynamics of the low molecular weight glass-former tris(naphthylbenzene) have been studied on the length scale of a few nanometers at the glass transition temperature T g . Neutron reflectivity was used to measure isotopic interdiffusion of multilayer samples created by physical vapor deposition. Deposition with the substrate held at T g − 6 K allows observation of dynamics characterizing the equilibrium supercooled liquid. The diffusion coefficient measured at q = 0.03 Å − 1 was determined to be 1 × 10 − 17 cm 2 ∕ s at 342 K ( T g ) . The self-part of the intermediate scattering function I s ( q , t ) decays exponentially. Samples deposited well below T g show a substantial thermal history effect during subsequent translational motion at T g .