共查询到20条相似文献,搜索用时 15 毫秒
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Langer J Dabkowska I Zhang Y Illenberger E 《Physical chemistry chemical physics : PCCP》2008,10(11):1523-1531
Electron attachment to pentafluorobenzonitrile (C(6)F(5)CN) and pentafluoronitrobenzene (C(6)F(5)NO(2)) is studied in the energy range 0-16 eV by means of a crossed electron-molecular beam experiment with mass spectrometric detection of the anions. We find that pentafluoronitrobenzene exclusively generates fragment anions via dissociative electron attachment (DEA), while pentafluorobenzonitrile forms a long lived parent anion within a narrow energy range close to 0 eV and additionally undergoes DEA at higher energies. This is in contrast to the behaviour of the non-fluorinated analogues as in nitrobenzene the non-decomposed anion is formed while in benzonitrile only DEA is observed. The associated reactions involve simple bond cleavages but also complex unimolecular decompositions associated with structural and electronic rearrangement also resulting in the deterioration of the cyclic structure. 相似文献
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Russian Chemical Bulletin - The modified dipeptide, Captopril, was studied to determine the effect of lateral functional groups on the decay of biomolecules in resonant reactions of electrons with... 相似文献
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SINDO1 calculations were performed to study the reactivity of molecules with a valence number derived from the density matrix. A comparison of valence numbers was made for selected examples of rotation barriers, substituted strained molecules, radical gas phase reactions, and acid-base reactions. Relations between valence, geometry, and energy changes are discussed. 相似文献
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Broad resonances in electron scattering by H2O, aliphatic alcohols and phenol are reported. 相似文献
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Dashevskaya EI Litvin I Nikitin EE Troe J 《The journal of physical chemistry. A》2011,115(25):6825-6830
Numerically accurate and analytically approximated partial wave probabilities for the capture of a charged particle by a stationary polarizable dipole are presented over wide ranges of collision energies. The results facilitate the analysis of electron-molecule attachment in terms of capture rates, contributions from electron-phonon coupling, and kinetic properties when metastable anions are formed. 相似文献
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S. V. Pikhtovnikov V. K. Mavrodiev I. I. Furley R. R. Gataullin I. B. Abdrakhmanov 《High Energy Chemistry》2006,40(4):224-229
Processes of the formation of negative ions from aniline and its derivatives were studied by the resonance electron capture technique. The results were compared with those obtained earlier for molecules of benzene, phenol, and chlorophenols. It was concluded that the processes of formation of negative ions in aniline differ substantially from those in benzene and phenol. The triplet series of resonances beginning from the resonance at 2.6 eV is observed. 相似文献
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V. S. Shmakov I. I. Furley A. Sh. Sultanov V. A. Dokichev R. M. Sultanova 《Russian Chemical Bulletin》2000,49(4):705-708
The negative ion mass spectra and photoelectron spectra of substituted pyrazolines were studied. A correlation between the
ionization energy of the highest occupied molecular orbital and the yield of [MeNHNH2
−] ions was found. Isomerization of molecular negative ions was studied by resonance electron capture mass spectrometry.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 701–704, April, 2000. 相似文献
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R. O. Macêdo O. M. de Moura A. G. de Souza A. M. C. Macêdo 《Journal of Thermal Analysis and Calorimetry》1997,49(2):857-862
This work present comparative results on powder milk storage quality, obtained from analytical methods. Protein content was determined conventional (Kjeldahl) and colorimetric with biuret reagent at 540 nm and integral quality by thermogravimetric and biological methods. A method was developed for the protein separation of powder milk. Powder milk was submitted to degradation processes at 45, 60 and 80°C for 20 days. The results indicated that protein content values were inconsistent if determinations by Kjeldahl and colorimetric methods and biological tests were compared. There is evidence of thermal decomposition of powder milk as detected by biological and thermogravimetric methods.The authors thanks CNPq/PADCT for financial support. 相似文献
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Dž. Belkić S. Saini H. S. Taylor 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1986,3(1):59-67
Whenever a collision takes place between charged particles, the first Born approximation for electron capture from hydrogenlike ions (Z T ,e) by a bare nucleusZ P , must be modified in order to account for the long-range Coulomb effects. One of the simplest ways to fulfill this requirement is provided by theT-matrix of the following form: $$T_{if}^{(1)} = \left\langle {\Phi _f exp\left\{ { - i\frac{{Z_T (Z_p - 1)}}{\upsilon } ln (\upsilon R + v \cdot R)} \right\}\left| {\frac{{Z_P }}{R} - \frac{{Z_P }}{{r_P }}} \right| exp\left\{ {i\frac{{Z_P (Z_T - 1)}}{\upsilon } ln (\upsilon R + v \cdot R)} \right\}\Phi _i } \right\rangle $$ where Φ's are the usual unperturbed channel states andZ's are the nuclear charges. In this transition amplitude, both initial and final scattering states satisfy the correct asymptotic boundary conditions in their respective channels. In the present paper, detailed computation of theK-shell cross sections is carried out for charge exchange in H+-H and H+-Ar collisions. The results are in good agreement with experimental data. 相似文献
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V. S. Shmakov I. I. Furley A. D. Ulendeeva N. K. Lyapina 《Russian Chemical Bulletin》1997,46(8):1472-1473
Using negative ion mass spectrometry in the mode of resonance electron capture, it was found that the energy of dissociation
of the S−S bond in dialkyl trisulfides is 0.6 eV smaller than that in their disulfide analogs and is equal to 1.9±0.1 eV.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1536–1537, August, 1997. 相似文献
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A. S. Vorob'ev I. I. Furlei A. Sh. Sultanov E. A. Burmistrov 《Russian Chemical Bulletin》1997,46(10):1797-1799
Negative-ion mass spectrometry in the mode of resonance capture of electrons and photoelectron spectroscopy in combination
with quantum-chemical calculations showed that the formation of the resonance states of negative molecular ions in the reaction
of electrons with molecules of the mechanism of intershell Feshbach resonance with the consecutive excitation of an electron
from several higher occupied MO to one vacant MO. In a low-energy region, the resonance at 1.4 eV is a resonance of form and
the resonance at 3–4 eV is the usual electron exciting Feshbach resonance with a parent triplet state (π.π*)3. The one and the same vacant π*CC MO is “active” in all the resonances mentioned.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1892–1894, October, 1997. 相似文献
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Yu. S. Nekrasov V. K. Mavrodiev V. A. Mazunov V. I. Khvostenko N. P. Avakyan I. I. Kritskaya 《Russian Chemical Bulletin》1985,34(6):1308-1310
Conclusions The major pathways were established for the fragmentation of -allyliron tricarbonyl halides upon dissociative electron capture. The mechanisms for the formation of C3H5Fe(CO)
3
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anions in the gas phase and under electrochemical reduction conditions on a dropping mercury electrode were shown to differ. A predominant effect was proposed for solvation factors on the electrochemical reduction in the condensed phase.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1428–1430. 相似文献
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M. V. Muftakhov R. V. Khatymov V. A. Mazunov V. N. Odinokov I. V. Galyautdinov 《Russian Chemical Bulletin》2000,49(4):713-716
The peculiarities of dissociative electron capture by 20-hydroxyecdysone molecules with the formation of fragment negative
ions were studied. In the region of high electron energies (5–10 eV), processes of skeleton bond rupture are accompanied by
the elimination of H2O and H2 molecules. In the region of thermal energies of electrons (≈0 eV), the mass spectrum is formed mainly by the [M−nH2O].− (n=1–3) and [M−H2−nH2O].− (n=0−3) ions that are generated exclusively by the rearrangement.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 709–712, April, 2000. 相似文献
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V. I. Khvostenko I. I. Furlei V. K. Mavrodiev G. V. Leplyanin A. R. Derzhinskii 《Russian Chemical Bulletin》1984,33(7):1517-1519
Conclusions The low energy resonance in the negative ion mass spectra of alkyl vinyl, 2,3-epoxypropyl alkyl, and 2, 3-epithiopropyl alkyl sulfies and their sulfoxide and sulfone analogs is related to electron capture in the * orbital of the S-C bond. The oxidation state of the sulfur atom has no qualitative effect on the major processes involved in the formation of the negative ions.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, 1653–1657, July, 1984. 相似文献
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X He G Xia Y Zhou M Zhang T Shen 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》1999,(4):873-880
Photophysical properties (absorption spectra, fluorescence spectra, lifetimes and quantum yields) were studied for the three isomers of tetrapyridylporphyrins (TPyPs) in CHCl3 and tetra-(N-hexadecylpyridiniumyl) porphyrins (TC16PyPs) in CHCl3, CH3OH and Triton X-100 micelle solution. While the ground-state and excited-state properties are very similar for the three isomers of neutral TPyP, significant differences exist among the isomers of amphiphilic TC16PyP. Amphiphilic porphyrins bearing hydrophilic pyridinium and hydrophobic long-chain alkyl groups are characterized by reduced fluorescence quantum yields, biexponential fluorescence decay, and appreciable aggregation in nonpolar solvents. The observed biexponential fluorescence decay of amphiphilic porphyrins can be interpreted in terms of mixing of the S1 and a close-lying CT state in which an electron is transferred from the porphyrin core to the electron-deficient pyridinium group. 相似文献