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1.
The reactivity of preheated and -irradiated TiO2 was observed in KI solution by studying the kinetics of liberation of I2. The rate of the reaction was found to be low.
species proposed on the surface of oxide probably dissociate into
. surface sites which oxidize I– ions to produce free I2. During irradiation
and
are produced which are reducing in nature and therefore very low yields of I2 are observed for low -doses. In further irradiation the reformation of –O–O–, peroxy linkages is proposed hence the observed higher yields. All the processes ultimately lead to an oscillatory variation in yields of I2 with -doses. 相似文献
2.
Peter C. Burgers John L. Holmes Johan K. Terlouw Ben van Baar 《Journal of mass spectrometry : JMS》1985,20(3):202-206
Three new [C2H6O]+˙ ions have been generated in the gas phase by appropriate dissociative ionizations and characterized by means of their metastable and collisionally induced fragmentations. The heats of formation, ΔHf0, of the two ions which were assigned the structures [CH3O(H)CH2]+˙ and [CH3CHOH2]+˙ could not be measured. The third isomer, to which the structure \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm CH}_{\rm 2} = \mathop {\rm C}\limits^{\rm .} {\rm H} \cdot \cdot \cdot \mathop {\rm H}\limits^ + \cdot \cdot \cdot {\rm OH}_{\rm 2} $\end{document} is tentatively assigned, was measured to have ΔHf0 = 732±5 kJ mol?1, making it the [C2H6O]+˙ isomer of lowest experimental heat of formation. It was found that the exothermic ion–radical recombinations [CH2OH]++CH3˙→[CH3O(H)CH2]+˙ and \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm CH}_{\rm 3} \mathop {\rm C}\limits^{\rm + } {\rm HOH + H}^{\rm .} $\end{document}→[CH3CHOH2]+˙ have large energy barriers, 1.4 and ?0.9 eV, respectively, whereas the recombinations yielding [CH3CH2OH]+˙ have little or none. 相似文献
3.
B. Bisplinghoff V. Bradnova R. Brandt K. K. Dwivedi V. S. Butsev E. M. Friedlander S. Gosh Guo Shi-Lun M. Heck Jin Huimin M. I. Krivopustov B. A. Kulakov C. Laue L. Lerman Th. Schmidt A. N. Sosnin Wang Yu-Lan 《Journal of Radioanalytical and Nuclear Chemistry》1995,189(2):191-206
An extended Cu-target was irradiated with 22 and 44 GeV carbon ions for about 11.3 and 14.7 hours, respectively. The upper side of the target was in contact with a paraffin-block for the moderation of secondary neutrons. Small holes in the moderator were filled with either lanthanum salts or uranium oxide. The reaction
was studied via the decay of140La(40h) using radiochemical methods, as has been published. The reaction
was studied via the decay of239Np(2.3 d) as well as the reaction U(n,f) using radiochemical methods. In addition, solid state nuclear track detectors were used for fission studies in gold. The yields for the formation of (n,) products agree essentially with other experiments on extended targets carried out at the Dubna Synchrophasotron (LHE, JINR). To a first approximation, the breeding rate of (n, ) products doubles when the carbon energy increases from 22 to 44 GeV. If, however, results at 44 GeV are compared in detail to those at 22 GeV, we observe an excess of (37±9)% in the experimentally observed239Np-breeding rate over theoretical estimations. Experiments using solid state nuclear track detectors give similar results. We present a conception for the interpretation of this fact: There is the evident connection between anomalies we observe in the yield of secondary particles in relativistic heavy ion interactions above a total energy of approximately 30–35 GeV and increased yield of neutrons in this energy region. 相似文献
4.
J. L. Oscarson R. M. Izatt P. R. Brown Z. Pawlak S. E. Gillespie J. J. Christensen 《Journal of solution chemistry》1988,17(9):841-863
The aqueous reactions,
相似文献
5.
V. R. S. Rao G. Erdtmann H. Petri 《Journal of Radioanalytical and Nuclear Chemistry》1989,135(4):257-264
The extent of exchange of bromine-82 with bromamine-T in strong acid medium is low due to the formation of
at lower acid concentrations and bromine at higher acidities.
formation occurs over a narrow acid concentration range and is less stable than
. 相似文献
6.
Peter C. Burgers John I. Holmes Cornelis E. C. A. Hop Johan K. Terlouw 《Journal of mass spectrometry : JMS》1986,21(9):549-555
From a combination of isotopic substitution, time-resolved measurements and sequential collision experiments, it was proposed that whereas ionized methyl acetate prior to fragmentation rearranges largely into \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm CH}_3 \mathop {\rm C}\limits^ + ({\rm OH}){\rm O}\mathop {\rm C}\limits^{\rm .} {\rm H}_2 $\end{document}, in contrast, methyl propanoate molecular ions isomerize into \documentclass{article}\pagestyle{empty}\begin{document}$ \mathop {\rm C}\limits^. {\rm H}_2 {\rm CH}_2 \mathop {\rm C}\limits^ + ({\rm OH}){\rm OCH}_3 $\end{document}. Metastably fragmenting methyl acetate molecular ions are known predominantly to form H2?OH together with \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm CH}_3 - \mathop {\rm C}\limits^ + = {\rm O} $\end{document}, whereas ionized methyl propanoate largely yields H3CO˙ together with \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm CH}_3 {\rm CH}_2 - \mathop {\rm C}\limits^ + = {\rm O} $\end{document}. The observations were explained in terms of the participation of different distonic molecular ions. The enol form of ionized methyl acetate generates substantially more H3CO˙ in admixture with H2?OH than the keto tautomer. This is ascribed to the rearrangement of the enol ion to the keto form being partially rate determining, which results in a wider range of internal energies among metastably fragmenting enol ions. Extensive ab initio calculations at a high level of theory would be required to establish detailed reaction mechanisms. 相似文献
7.
Characterization of [C4H5O]+ ions in the gas phase using their collisional activation spectra shows that the four C3H5\documentclass{article}\pagestyle{empty}\begin{document} $\mathop {\rm C}\limits^ + =\!= $\end{document}O isomers CH2?C(CH3)\documentclass{article}\pagestyle{empty}\begin{document} $\mathop {\rm C}\limits^ + =\!= $\end{document}O, CH2?CHCH2\documentclass{article}\pagestyle{empty}\begin{document} $\mathop {\rm C}\limits^ + =\!= $\end{document}O, CH3CH?CH\documentclass{article}\pagestyle{empty}\begin{document} $\mathop {\rm C}\limits^ + =\!= $\end{document}O and ?? \documentclass{article}\pagestyle{empty}\begin{document} $\mathop {\rm C}\limits^ + =\!= $\end{document}O are stable for ≥ 10?5 s. It is concluded further from the characteristic shapes for the unimolecular loss of CO from C3H5\documentclass{article}\pagestyle{empty}\begin{document} $\mathop {\rm C}\limits^ + =\!= $\end{document}O ions generated from a series of precursor molecules that the CH2?CH(CH3)\documentclass{article}\pagestyle{empty}\begin{document} $\mathop {\rm C}\limits^ + =\!= $\end{document}O- and CH2?CHCH2\documentclass{article}\pagestyle{empty}\begin{document} $\mathop {\rm C}\limits^ + =\!= $\end{document}O-type ions dissociate over different potential surfaces to yield [allyl]+ and [2-propenyl]+ [C3H5]+ product ions respectively. Cyclopropyl carbonyl-type ions lose CO with a large kinetic energy release, which points to ring opening in the transition state, whereas this loss from CH3CH?CH\documentclass{article}\pagestyle{empty}\begin{document} $\mathop {\rm C}\limits^ + =\!= $\end{document}O-type ions is proposed to occur via a rate determining 1,2-H shift to yield 2-propenyl cations. 相似文献
8.
O. A. Luk'yanov A. A. Onishchenko V. P. Gorelik V. A. Tartakovskii 《Russian Chemical Bulletin》1973,22(6):1251-1254
Conclusions The intramolecular alkylation of the anions of nitramines of type
goes by the O-alkylation scheme with the formation of the derivatives of 4,5-dihydro-1,2,3-oxadiazole 2-oxides.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1294–1298, June, 1973. 相似文献
9.
10.
P. K. Mishra V. Chakravortty K. C. Dash N. R. Das S. N. Bhattacharyya 《Journal of Radioanalytical and Nuclear Chemistry》1989,134(2):259-264
Synergism has been observed in the extraction of zirconium(IV) by mixtures of Aliquat 336 or Alamine 336 with a neutral donor TBP from aq. HCl solutions. Although the extractant dependency for Zr(IV) is found to be nearly second power with respect to TBP alone, monosolvate is found to be formed for extraction by its mixture with Aliquat 336 or Almine 336. Quantitative extraction is observed with mixtures at a lower acidity than that with individual extractants. The species formed is tentatively assigned to be Q2ZrCl6. TBP, where
for Aliquat 336 and
for Alamine 336. 相似文献
11.
M. I. Kabachnik D. I. Lobanov A. G. Matveeva O. E. Kovsheva M. I. Terekhova É. S. Petrov P. V. Petrovskii E. I. Matrosov 《Russian Chemical Bulletin》1991,40(7):1417-1422
Several substituted methylaminotriphenylphosphonium salts (APS) of general formula
have been synthesized. The CH-acidities of some of the prepared APS have been measured by the indicator method in DMSO, with K+ counterion and 9-phenylfluorene (pK 18.5) as standard, showing a pK range of 14.7–24.8. The acidification effect of
and
groups has been evaluated. The results obtained suggest that there is an effective charge on the nitrogen atom in the APS studied and an increased multiplicity of the N-P bond.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1598–1604, July, 1991. 相似文献
12.
Balaprasad G. Ankamwar Madukar D. Bhand Gavisiddappa S. Gokavi 《Transition Metal Chemistry》1993,18(4):361-363
The reaction between VV and TlI was studied in 4.0 mol dm–3 HCl at an ionic strength of 4.1 mol dm–3 at 25° C. The main active species under the reaction conditions were found to be VO
inf2
sup+
and TlCl
inf3
sup2–
for the oxidant and reductant, respectively. A probable mechanism in terms of these species is given, and follows the rate law:
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