Temperature-dependent rotational relaxation in a viscous alkane: Interplay of shape factor and boundary condition on molecular rotation

2003 ◽  
Vol 118 (18) ◽  
pp. 8307-8314 ◽  
Author(s):  
G. B. Dutt ◽  
A. Sachdeva
Keyword(s):  
Boundary Condition ◽  
Shape Factor ◽  
Molecular Rotation ◽  
Rotational Relaxation ◽  
Temperature Dependent

One-phase Stefan problem with temperature-dependent thermal conductivity and a boundary condition of Robin type

2015 ◽  
Vol 21 (2) ◽  
Author(s):  
Adriana C. Briozzo ◽  
María Fernanda Natale
Keyword(s):  
Thermal Conductivity ◽  
Boundary Condition ◽  
Stefan Problem ◽  
Temperature Dependent ◽  
Temperature Dependent Thermal Conductivity

AbstractWe study a one-phase Stefan problem for a semi-infinite material with temperature-dependent thermal conductivity with a boundary condition of Robin type at the fixed face

Investigation of the Natural Convection Boundary Condition in Microfabricated Structures

2005 ◽  
Author(s):  
Xuejiao Hu ◽  
Ankur Jain ◽  
Kenneth E. Goodson
Keyword(s):  
Thin Film ◽  
Boundary Condition ◽  
Heat Conduction ◽  
Natural Convection ◽  
Shape Factor ◽  
Analytical Modeling ◽  
Convection Boundary Condition ◽  
Convection Boundary ◽  
3 Omega ◽  
Thin Film Membrane

Heat loss through surrounding air has important thermal effect on microfabricated structures. This effect is generally modeled as a natural convection boundary condition. However, how to determine the convective coefficient (h) at microscales is a debate. In this paper, a micro heater is fabricated on a suspended thin film membrane. The natural convection is investigated using the 3-omega measurements and complex analytical modeling. It is found that h seems larger than that at larger scales; however, it is also proved that the increased h is actually contributed by heat conduction instead of heat convection. A method of determining the phenomenal h that can be used for microfabricated structures is proposed by using the heat conduction shape factor.

Temperature-dependent UV absorption of biphenyl based on intra-molecular rotation investigated within a combined experimental and TD-DFT approach

2018 ◽  
Vol 45 (13-15) ◽  
pp. 2048-2053 ◽  
Author(s):  
Adriana Pietropaolo ◽  
Concetta Cozza ◽  
Zhaoming Zhang ◽  
Tamaki Nakano
Keyword(s):  
Molecular Rotation ◽  
Uv Absorption ◽  
Temperature Dependent ◽  
Td Dft

Kernresonanzuntersuchung der Molekülrotation in festem Benzol: T1-Spektroskopie / Nuclear Magnetic Resonance Investigation of Molecular Rotation in Solid Benzene: T1-spectroscopy

1974 ◽  
Vol 29 (11) ◽  
pp. 1660-1670 ◽  
Author(s):  
J. Wendt ◽  
F. Noack
Keyword(s):  
Activation Energy ◽  
Gear Wheel ◽  
Larmor Frequency ◽  
Molecular Rotation ◽  
Frequency Range ◽  
Temperature Dependent ◽  
Resonance Investigation ◽  
Reciprocal Temperature ◽  
Nuclear Magnetic Resonance Investigation ◽  
Magnetic Resonance Investigation

We have extended Haeberlen’s and Maier’s NMR investigation of the molecular rotation in solid polycrystalline benzene (C6H6), performed in 1967 in the Larmor frequency range from 88 MHz to 22 MHz, to lower frequencies down to 4.4 MHz. In some cases monocrystalline samples were also studied. The extensive data show that the presently accepted model of purely uncorrected rotations of the benzene molecules around their sixfold axis has to be rejected. Instead, two results found, namely- a slight increase of the rotational activation energy when approaching the melting point of benzene and- the width of the T1 relaxation minima as a function of the reciprocal temperature suggest an additional relevance of correlated molecular motions, like e.g. the ‘gear-wheel mechanism’ first proposed by Cox. By appropriate modifications of Haeberlen’s theory, i.e. by assuming a rate equation with temperature dependent activation energy and by emphasizing the effect of simultaneous rotations of neighbouring rings compared with the purely statistical, uncorrelated case, we succeeded to describe the considered T1 measurements quantitatively.

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