levels are unable to reproduce the experimental findings, suggesting that the trans form is slightly more stable. In the gas phase we find no evidence of the presence of a second conformer, and we know that the cis form is both present (from the microwave spectrum)19 and predominant (from the electron diffraction study),7 but we still cannot exclude the possibility that a small proportion of a second conformer is also present in the gas phase.Acknowledgment. The authors gratefully acknowledge financial support of this research by the National Science Foundation by Grant CHE-83-11279 and the NATO Scientific Affairs Division through their collaborative research program under Grant No. 140/82. Registry No. CH3CH2NCO, 109-90-0.
The rate of change of the axial dipole moment with asymmetric bond extension in carbon diselenide has been computed from the measured gas phase infrared absorption intensity of the σ3 fundamental band. The absolute intensity was measured by the pressure-broadening technique, using nitrogen or air as the foreign gas. The magnitudes of dμ/dr for CO2, OCS, CS2, and CSe2 are compared. Also, the absorption intensity of the σ3 band of CSe2 dissolved in CS2 was measured.
The variations with temperature of near-resonant (V-V) deexcitation cross sections for CO2(00°l) + SiF4 and CO2(00°l) + SF6 were determined for 300 < / < 210, for two sets of compositions. Whereas previous experiments and theoretical models agreed that for T > 300 K increases proportional to 7"1, for several collision partners, the present values show a clear decrease of the cross sections from linear dependence on T~l. Indeed, it appears that values pass through a shallow maximum in the vicinity of T « 250 K.
ii) For such encounters, description of the distortions which occur in their structures, particularly in the acid molecule.iii) Estimation of the probability for the redistribution of energy from vibrational and internal rotational modes in which large amplitudes are localized around the newly formed bond to modes in which large amplitudes appear in cther parts of the molecules. Consider dependence of this stabilization on the detailed composition and geometry of the reactants; is there a need for a third boay? iv) Estimation of the probability for the redistribution of energy from the vibratlonally excited product molecule to the ambient gas, relative to the probability for the re-accumulation of energy in the newly formed bond, and consequent dissociation. Consider dependence of this de-energization on the nature and concentration of the ambient gas.v) Estimation of the probability for the exchange reactions:AB 1 + B 2 -oAB 2 + B, and of AIB + A 2 ---PA 2 B + A,.Compare these rates with that of precipitation of AB 1 and AIB.vi) Description of the formation of crystal embryos and nuclei, and of the rate of growth of Lewis salt crystals. Consider possible re-evaporation of reac'ant species from these hot crystals due to insufficiently rapid trunsfer of the heat of condensation to the ambient gas. In the following papers attempts have been made to obtain experimental answers to some of the questicns raised. We have been only partially successful, and much work remains to be done.The last paper included in this final repcrt summarizes computational work by Mr. Nicholas Rol.Since the association mechanism in the gas phase of aliphatic acid monomers presumably has a number of kinetic features similar to that of Lewis acidbase adduct formation, the possibility of measuring these rates should be investigated.Mr. Rol considered the feasibility of exploiting shock tube techniques.We here express our sincere appreciation to the Office of Naval Research for the extended support given to this project.We are particularly thankful for the personal interest shown in our research efforts. It was demonstrated that the pair BFs-B 2 He are compatible in the sense that these gases do not react with each other to produce new substances and that the product of reaction with trimethylamine, in each case, is unaffected by the presence of the other acid. The ratio of the overall rates of addition _RIs-NMes/RB2He-NMes increases with rising temperature, rather than decreases, as is expected were a displacement mechanism operative, such as:NMes + BraHe MesN:BHs + BHK Also, this ratio decreases with increasing pressure of the amine but for constant amine and acid concentrations is independent of the ambient pressure (N 2 diluent). (kf/ka) -2.2, and, log (kfAakb) --6.620 -271.7/T An analysis of these results will be presented.
We continued the study of the accelerated decomposition of H3BPF3 induced by laser radiation (930-950 cm-1), and extended it to the fully deuterated species. While in all essential respects the kinetics of the ir photolysis for the two compounds are identical, the few differences which were uncovered proved crucial in pointing to interesting features of the mechanism. These verified predictions based on a normal mode analysis for the distribution of potential energy among the internal coordinates. For the laser augmented decomposition, EaL = 3.5 ± 1 kcal/mol, compared with Eath = 29.3 kcal/mol for the thermal process. The quantum efficiency is low, «4 X 104 photons/molecule decomposed. The rates of decomposition depend on the isotopic content and are sensitively dependent on the frequency of the irradiating line. For example, with P(24) large fractionation ratios were found for D3BPF3 vs. H3BPF3, and small differences for D311BPF3 vs. D310BPF3. The levels of decomposition induced by the sequential three-photon absorption have been semiquantitative-
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.