695 research outputs found

    Thermodynamic Properties of the Internal Rotation in Methyl Alcohol Vapor from 200 to 500°K

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    At ordinary and lower temperatures the thermodynamic properties of the methyl alcohol internal rotation are beyond the limits of available tabulations. For any internal rotator, of a given symmetry, with a fixed moment of inertia and potential barrier, two limiting values of each property can be calculated for any chosen temperature. Available tables are restricted to those cases for which the differences between the limiting values can be neglected. When, as with methyl alcohol, the differences are large, the representative values can be found by taking proper account of the symmetry and the dependence of the internal rotator energy levels upon the external rotations.For methyl alcohol, the correct intermediate thermodynamic properties are obtained by using for the partition function and its derivatives the numerical mean of the limiting values of these sums obtained for the general rotator. This simple rule, however, is not necessarily applicable to other compounds.Heat capacities and entropies, calculated from the spectroscopic potential barrier of 932 cal./mole and other molecular constants, are considered in relation to experimental data.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/69898/2/JCPSA6-18-8-1051-1.pd

    Hindered Rotation in Methyl Alcohol with Note on Ethyl Alcohol

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    The potential barrier to the internal rotation in methyl alcohol is recalculated from the entropy with the aid of new molecular dimensions generously provided by Burkhard and Dennison. The barrier calculation is examined for temperature dependence and checked for reliability by recalculation with the Clapeyron equation substituted for parts of the data. The result is 1600±700 cal./mole, which includes the new spectroscopic barrier of Burkhard and Dennison at 326 cm−1. Within the range covered by the result, a residual entropy up to 0.50 cal./mole deg. is possible, and the retention of 0.46 e.u. by the crystal is consistent with a reasonable simple assumption about the distribution of hydrogen bonds.It is suggested, by analogy, that the barrier to the hydroxyl group rotation in ethyl alcohol should be about 1000 cal./mole.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/71293/2/JCPSA6-18-3-361-1.pd

    Decoupling electrocaloric effect from Joule heating in a solid state cooling device

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    We report a heat dynamics analysis of the electrocaloric effect (ECE) in commercial multilayer capacitors based on BaTiO3 dielectric, a promising candidate for applications as a solid state cooling device. Direct measurements of the time evolution of the sample's temperature changes under different applied voltages allow us to decouple the contributions from Joule heating and from the ECE. Heat balance equations were used to model the thermal coupling between different parts of the system. Fingerprints of Joule heating and the ECE could be resolved at different time scales. We argue that Joule heating and the thermal coupling of the device to the environment must be carefully taken in to account in future developments of refrigeration technologies employing the ECE.Comment: Acepted to be published in Applied Phys. Letters (2011

    The Infra‐Red Absorption Spectra of Ethylene and Tetra‐Deutero‐Ethylene under High Resolution

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    The fine structure of several infra‐red absorption bands of C2H4 and C2D4 have been resolved. From the rotational constants so found, the C☒C and C☒H distances in this molecule were calculated to be 1.353 and 1.071A, and the H☒C☒H angle to be 119°55′. An assignment of fundamental frequencies has been made which is consistent with the observed data.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/69770/2/JCPSA6-10-2-88-1.pd

    European economic constitution and the transformation of democracy : on class and the state of law

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    In the context of contemporary analyses of the Europe Union as a post-democratic form of economic governance, this article explores the (ordo)liberal character of monetary union as a regime of imposed liberty. The argument holds that rather than forcing the member states into retreat, the economic constitution of Europe strengthens their liberal foundation, securing their utility as the organised force of a mode of social reproduction founded on free labour. It develops the character of the liberal state as the political form of a free market economy with reference to Adam Smith’s classical political economy and the German ordoliberal tradition, which calls for a rule-based system of federated forms of economic governance to secure a free labour economy in conditions of mass democratic aspirations for a freedom from want. It explores the rationale of the ordoliberal distinction between the liberal character and the democratic character of the state and, in this context, assesses the meaning of liberal democracy in a post-democratic Eurozone
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