Intramolecular end-to-end excimer formation of bis[(1-pyrenylmethoxy)carbonyl]alkanes. A study of end-to-end collisional frequency on a chain molecule

1982 ◽  
Vol 104 (13) ◽  
pp. 3580-3587 ◽  
Author(s):  
T. Kanaya ◽  
K. Goshiki ◽  
M. Yamamoto ◽  
Y. Nishijima
1998 ◽  
Vol 109 (5) ◽  
pp. 2011-2022 ◽  
Author(s):  
Hin Hark Gan ◽  
Byung Chan Eu
Keyword(s):  

1983 ◽  
Vol 38 (12) ◽  
pp. 1285-1292 ◽  
Author(s):  
J. A. Borges da Costa ◽  
C. Scherer ◽  
A. Holz ◽  
J. Naghizadeh

Abstract The torsional modes of a chain molecule were studied recently under the assumption that it has a well defined spatial configuration at any time. Here we show how the averages over the possible configurations, for a distribution in thermal equilibrium, should be performed in the calculation of the thermodynamical properties. Our results show that the mean density of torsional states increases in the low frequency region with increasing temperature. The specific heat behaviour shows a considerable difference from the result obtained in the previous paper, where only the lowest energetic configuration was considered. The consequences of this result with respect to the configurational properties of polymer molecules near the θ temperature are discussed.


FEBS Letters ◽  
1988 ◽  
Vol 241 (1-2) ◽  
pp. 136-140 ◽  
Author(s):  
D. Čechová ◽  
E. Töpfer-Petersen ◽  
A. Henschen

The rotation of the CH 3 groups round the single C—C bond in ethane is associated with a threshold energy of about 3000 gcal./gmol. or 2 x 10 -13 erg/mol. (Schäfer 1938; Kistiakowsky, Lacher and Strutt 1939). In an aliphatic CH 2 chain where the carbon atoms are linked together by single bonds the corresponding energy must be of the same order and is most likely rather smaller. Supposing we consider any particular C—C bond in the chain and treat the two parts at each side of this bond as rigid rotators, then their kinetic energy would be 2 x 1/2 kT which at room temperature amounts to about one-fifth of the threshold energy. It seems very likely under these circumstances that a chain molecule of say ten to twenty carbon atoms should already at room temperature show signs of distortion due to internal rotation. If this is true, then the previously observed increase of the crystal symmetry at the melting-point of paraffins (Müller 1930, 1932) and the corresponding changes of the polarization of long-chain ketones (Müller 1937, 1938) can no longer be ascribed entirely to a rotation of the molecule in the field of the surrounding molecules but must at least partly be due to this internal distortion. It is clear that a distortion of this type tends to destroy the anisotropy of the molecule and to give an apparent isotropy to the crystal. The present experiments were made in order to obtain an estimate of the magnitude of the distortion effect. It is found to be surprisingly large.


Open Physics ◽  
2012 ◽  
Vol 10 (3) ◽  
Author(s):  
Davide Valenti ◽  
Giovanni Denaro ◽  
Dominique Adorno ◽  
Nicola Pizzolato ◽  
Salvatore Zammito ◽  
...  

AbstractPolymer translocation through the nanochannel is studied by means of a Monte Carlo approach, in the presence of a static or oscillating external electric voltage. The polymer is described as a chain molecule according to the two-dimensional “bond fluctuation model”. It moves through a piecewise linear channel, which mimics a nanopore in a biological membrane. The monomers of the chain interact with the walls of the channel, modelled as a reflecting barrier. We analyze the polymer dynamics, concentrating on the translocation time through the channel, when an external electric field is applied. By introducing a source of coloured noise, we analyze the effect of correlated random fluctuations on the polymer translocation dynamics.


1969 ◽  
Vol 51 (3) ◽  
pp. 1215-1221 ◽  
Author(s):  
Robert Yeh ◽  
A. Isihara
Keyword(s):  

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