Internal Energy Effects Research Articles

Internal energy effects on the reaction of D3+with CH4

A tandem mass spectrometer has been used to measure the distribution of ionic products resulting from the reaction of D3+ with CH4 as a function of the average number of D3+-D2 collisions occurring in the source. These results provide information on the amount of internal excitation energy in D3+. It is shown that at least 69% of the D3+ ions are formed with 0.6 eV or more excitation energy. These results are compared with an approximate D3+ excitation energy distribution based upon a statistical model which assumes a random distribution of energy among the vibrational and translational states of the products of the reaction of D2+ with D2. Reasonable agreement was obtained.

A new tandem mass spectrometer for the study of ion-molecule reactions

Essential design and construction details and some preliminary results are given for a new tandem mass spectrometer which was designed for the study of low (approximately thermal) energy ion-molecule reactions. The first stage of the instrument consists of a 180 degree, 5.7 cm radius magnetic mass spectrometer which provides a beam of mass analyzed reactant ions. The second stage of the instrument consists of a deceleration lens and an ion cyclotron resonance mass spectrometer. A moderately high pressure source in the first stage of the instrument permits studies of reactant ions which are themselves products of ion-molecule reactions. Differential pumping isolates the ion source from the collision region and therefore permits detailed studies of internal energy effects on ion-molecule reactions.

Internal energy effects on metastable characteristics. The structure of [C3H7O]+ ions

AbstractThe effect of changes in the internal energy distribution of the fragmenting ion on the ratio of metastable ion intensities for two competing fragmentation reactions has been investigated both theoretically and experimentally. Model calculations have shown that if the competing reactions have significantly different activation energies the metastable intensity ratio does depend on the internal energy distribution although large changes are necessary before the ratio changes by more than a factor of two. Experimentally the metastable characteristics of [C3H7O]+ ions of nominal structures [CH3CH2O+CH2] (I), [(CH3)2CO+H] (II), [CH3CH2CHO+H] (III) and [CH3O+CHCH3] (IV) have been examined. For each structure the metastable characteristics are found to be distinctive and independent of changes in the internal energy distribution of the fragmenting ion where these changes result from altering the precursor of the [C3H7O]+ ions. It is suggested that these internal energy changes can be estimated from the fraction of [C3H7O]+ ions which fragment in the ion‐source. It is concluded that structures I to IV represent stable and distinct ionic structures.

Internal energy effects on the mass spectral fragmentations of some phosphorus heterocycles

AbstractIn addition to the elimination of C6H5· and C7H7·, 2,8‐dimethyl‐10‐phenyl‐ and 10‐(p‐tolyl)‐phenothiaphosphines lost C6H5S· and C7H7S·, respectively from high internal energy molecular ions, while the low internal energy ions eliminated C6H5PH and C7H7PH, respectively. 2,8‐Dimethyl‐10‐phenylphenoxaphosphine lost C6H5·, C6H5P and C6H5PH· both in the source and in the first field‐free region, but the expulsion of C6H5O· was not observed.

Viscoelastic behavior of plasticized polyvinyl chloride at large deformations. II. Creep

AbstractPlasticized polyvinyl chloride has been found to undergo a permanent deformation when strained past 100%. At the same strains, internal energy effects become pronounced as reflected in the stress‐strain curves. Plasticizer efficiency has been evaluated in several respects, namely rubber‐like behavior, recovery, glass transition, set, and stress‐strain at break. While no single plasticizer stands out, the following sequence has been established with respect to the first four aspects listed above: DOA ≥ TCP > DPP ≥ ARO.