Temperature dependence of the vibrational relaxation processes in natural and isotopically pure 32S8: Effect of the isotopic impurities on infrared phonon lifetimes

1997 ◽  
Vol 106 (2) ◽  
pp. 511-518 ◽  
Author(s):  
R. Bini ◽  
S. Califano ◽  
B. Eckert ◽  
H. J. Jodl
1992 ◽  
Vol 96 (1) ◽  
pp. 98-109 ◽  
Author(s):  
Maurizio Becucci ◽  
Emilio Castellucci ◽  
Paolo Foggi ◽  
Salvatore Califano ◽  
David A. Dows

1952 ◽  
Vol 25 (4) ◽  
pp. 720-729 ◽  
Author(s):  
John D. Ferry ◽  
Edwin R. Fitzgerald ◽  
Lester D. Grandine ◽  
Malcolm L. Williams

Abstract By the use of reduced variables, the temperature dependence and frequency dependence of dynamic mechanical properties of rubberlike materials can be interrelated without any arbitrary assumptions about the functional form of either The definitions of the reduced variables are based on some simple assumptions regarding the nature of relaxation processes. The real part of the reduced dynamic rigidity, plotted against the reduced frequency, gives a single composite curve for data over wide ranges of frequency and temperature; this is true also for the imaginary part of the rigidity or the dynamic viscosity. The real and imaginary parts of the rigidity, although independent measurements, are interrelated through the distribution function of relaxation times, and this relation provides a check on experimental results. First and second approximation methods of calculating the distribution function from dynamic data are given. The use of the distribution function to predict various types of time-dependent mechanical behavior is illustrated.


Polymer ◽  
2001 ◽  
Vol 42 (1) ◽  
pp. 289-295 ◽  
Author(s):  
S. Theobald ◽  
W. Pechhold ◽  
B. Stoll

1999 ◽  
Vol 559 ◽  
Author(s):  
F.M. Aliev ◽  
M. Kreuzer ◽  
Yu.P. Panarin

ABSTRACTNematic liquid crystal filled with Aerosil particles, a prospective composite material for optoelectronic application, has been investigated by static light scattering and Photon Correlation Spectroscopy (PCS). The Aerosil particles in filled nematic liquid crystals (FN) form a network structure with LC domains about 2500 Å in size with a random distribution of the director orientation of each domain.We found that the properties of 5CB are considerably affected by the network. The N-I phase transition in filled 5CB was found to be smeared out and depressed. PCS experiments show that two new relaxation processes appear in filled 5CB in addition to the director fluctuation process in bulk. The slow relaxation process, with a broad spectrum of relaxation times, is somewhat similar to the slow decay, which is observed in confined nematic liquid crystal.The middle frequency process was assigned to the director fluctuations in the surface layer formed at the particle-LC interface. The decay function describing this relaxation process is a stretched exponential (β ≍ 0.7). The temperature dependence of the relaxation times of the middle frequency obeys the Vogel-Rilcher law. Such a temperature dependence, accompanied by a broad spectrum of relaxation times suggests that the dynamics of the director fluctuations near the Aerosil particle-LC interface is glass-like.


2016 ◽  
Vol 18 (4) ◽  
pp. 3244-3249 ◽  
Author(s):  
Sangsu Lee ◽  
Hirotaka Mori ◽  
Taegon Lee ◽  
Manho Lim ◽  
Atsuhiro Osuka ◽  
...  

We demonstrate that the electronic deactivation overtakes the vibrational relaxation processes in the energy relaxation processes from the initially excited vibronic state manifolds in highly conjugated molecular systems.


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