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1.
Hiroshi Masuhara Yasuhiro Maeda Noboru Mataga Kyoichi Tomita Hitoshi Tatemitsu Yoshiteru Sakata Soichi Misumi 《Chemical physics letters》1980,69(1):182-184
Photoprimary processes of intramolecular exciplex systems of benzophenone and N,N-dimethylaniline were studied by means of laser spectroscopy. Electron transfer in acetonitrile and hydrogen abstraction in benzene occur quite rapidly almost independent of the number of methylene chain connecting both moieties, which indicates that a definite and restricted structure is not necessary for both processes. 相似文献
2.
The orientation of an 8 kG magnetic field with respect to the crystallographic axes is shown to affect the intensity of anthracene delayed fluorescence in an anthracene-doped phenanthrene crystal. These results are consistent with the calculated locations of level-crossing resonances for anthracene trapped-phenanthrene triplet exciton heterofusion. The line shapes of these level crossing resonances appear to be rather different from those reported for other cases of heterofusion or homofusion magnetic field resonances. 相似文献
3.
《Chemical physics letters》1987,136(1):42-46
The external magnetic field effects on the exciplex fluorescence of α-(4-dimethylaminophenyl)-ω-(9-phenanthryl)alkanes have been studied by photostationary, time-resolved, and magnetic field modulation fluorescence spectroscopy. The singlet-triplet degeneracy of the radical ion pair is suggested to occur at a methylene chain length of about ten. 相似文献
4.
E. E. Batova P. P. Levin V. Ya. Shafirovich V. A. Kuz'min 《Russian Chemical Bulletin》1995,44(3):427-431
The recombination kinetics of three photogenerated covalently-linked ketyl-phenoxyl triplet radical pairs,3[PhC.(OD)C6H4O(CH2)
n
OC6H4C6H4O.] (n=3, 6, and 10), and of the corresponding deuterated derivatives were examined by the laser flash technique under an external magnetic field (up to 0.2 T) in a CDCl3/CD3OD (21) mixture. In zero magnetic field, radical pairs (RPs) with small exchange interactions (n=6 and 10) are characterized by high values of the magnetic isotope effect (MIE), which reach 3 for pairs withn=10. Under strong magnetic fields (up to 0.2 T), the values of MIE decrease to 1.2 to 1.1. The photochemical behavior of covalently-linked RPs is compared with that of similar unlinked RPs in micelles.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 442–446, March, 1995.The authors are grateful to V. F. Tarasov, A. I. Shushin (N. N. Semenov Institute of Chemical Physics, RAS) and V. A. Nadtochenko (Institute of Chemical Physics in Chernogolovka, RAS) for helpful discussions. 相似文献
5.
At 20–70 °C, the temperature has almost no effect on the semisaturation field,B
1/2, or on the magnetic effects detected by exciplex fluorescence (pyrene/N,N-dimethylaniline) in binary benzene-DMSO mixtures. In individual solvents (ethanol, methanol) heating leads to a noticeable
increase in the magnetic effect, whileB
1/2 decreases. The results obtained corroborate a previously proposed hypothesis that polar microclusters are formed in binary
solvents with components of different polarity.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1821–1823, October, 1993. 相似文献
6.
V. P. Kondilenko T. A. Kikteva I. G. Tarasov A. M. Eremenko 《Theoretical and Experimental Chemistry》1997,33(3):157-160
The bimolecular photochemical quenching of the fluorescence of pyrene by N,N-dimethylaniline on the surface of various porous
silicas with low coverage of the surface (less than a monolayer) has been studied. The kinetics of this process on porous
and nonporous silica have been compared.
Institute of Surface Chemistry, National Academy of Sciences of Ukraine, 31 Prosp. Nauki, 252039, Kiev. Translated from Teoreticheskaya
i éksperimental’naya Khimiya, Vol. 33, No. 3, pp. 188–191, May–June, 1997. 相似文献
7.
Fluorescence, whose spectral and magnetic properties permit its assignment to the luminescence of a triplex exciplex, has been discovered at times 3 sec after photoexcitation in the luminescence spectrum of the pyrene+N,N-diethylaniline system in methanol at 600 nm by the method of nanosecond stroboscopic fluorometry.Translated from Teoreticheskaya i Eksperimental'naya Khimiya, Vol. 25, No. 5, pp. 623–626, September–October, 1989. 相似文献
8.
V. P. Kondilenko I. G. Tarasov V. V. Dudnik A. M. Eremenko 《Theoretical and Experimental Chemistry》1996,32(5):285-288
Pulsed-laser fluorometry has been used to study the features of formation of an excited-state donor-acceptor complex between pyrene and NN-dimethylaniline in the adsorbed state on an Aerosil surface, over a broad range of concentrations of the quenching agent.Institute of Surface Chemistry, National Academy of Sciences of the Ukraine, 31 Nauka Prospect, Kiev 252039, Ukraine. Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 32, No. 5, pp. 324–327, September–October, 1996. Original article submitted June 28, 1995. 相似文献
9.
Phosphorescence behavior of the series of compounds, (carbazole)-(CH2)n-(terephthalic acid methyl ester), which show intramolecular exciplex emission, has been studied in a rigid medium at 77 K. The phosphorescence of the carbazole moiety is enhanced by electron transfer fluorescence quenching of the carbazole residue in accord with the degree of quenching. 相似文献
10.
11.
Cabanillas-Gonzalez J Sciascia C Lanzani G Toffanin S Capelli R Ramon MC Muccini M Gierschner J Hwu TY Wong KT 《The journal of physical chemistry. B》2008,112(37):11605-11609
We report on the triplet spectra and dynamics in two types of oligomeric films deposited by two different techniques: thermal evaporation and spin coating. The different molecular arrangement in both films is manifested in a red shift of the absorption, PL, and T1-Tn absorption spectra of the sublimated film relative to the spin-coated one. Triplet recombination dynamics studied with steady-state photoinduced absorption (PA) spectroscopy follow a dispersive bimolecular recombination model away from the trap filling regime. We obtained values for the triplet bimolecular recombination ratio (beta) of 3.4 x 10 (-14) and 1.1 x 10 (-15) cm3 s (-1) for evaporated and spin-coated film, respectively, the difference being attributed to diverse molecular arrangement in both films. 相似文献
12.
Strong quenching of fluoroscence of pyrene by N,N-dimethylaniline as well as N,N-dimethylaniline sulfonate has been observed in aqueous micellar solutions. Photoinduced electron transfer from the anilines to excited pyrene near the micelle-water interface has been demonstrated by means of laser photolysis studies. 相似文献
13.
Sanjukta Aich Tamal Sengupta Amit Bhattacharyya Samita Basu 《Journal of polymer science. Part A, Polymer chemistry》1999,37(21):3910-3915
The present work emphasises the investigation of photoinduced electron transfer reaction between an electron-donor fluorophore, N-vinyl carbazole (VCZ), grafted on a polymeric cellulose acetate film and an electron-acceptor, 1,4-dicyanobenzene, in the presence of an external magnetic field that serves as a powerful tool to identify the spin states where the initial electron transfer occurs and to modulate the course of the reaction as desire. Here initial electron transfer occurs in the singlet spin state, and the formation of exciplex increases in the presence of magnetic field. The maximum field effect is obtained in the solvent with medium dielectric constant (εmax) around 8.0. The εmax value indicates that the extent of charge transfer in this exciplex is less compared to other similar systems studied so far, owing to the characteristic binding of VCZ to the polymeric backbone through oxygen atom. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 3910–3915, 1999 相似文献
14.
N. Kh. Petrov A. V. Starostin G. K. Chudinova M. V. Alfimov 《Russian Chemical Bulletin》1990,39(8):1746-1748
An external magnetic field was found to enhance the luminescence of pyrene-N,N-dimethylaniline exciplexes in a solution of reverse micelles containing water, OT Aerosol, and pentanol (0.6%, B=30 mT). The field dependence of the relative change in the intensity of the exciplex fluorescence does not reach saturation for fields with magnetic induction up to 30 mT, which is not observed in polar homogeneous solutions. These results may be attributed to the circumstance that a significant fraction of pyrene (up to 30%) is localized in the interphase of the reverse micelles.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 8, pp. 1918–1920, August, 1990. 相似文献
15.
Anton K. Kuzaev Aleksey M. Grobov Evgenii M. Pliss Anatoly L. Buchachenko 《Mendeleev Communications》2021,31(3):341-342
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16.
Nanosecond laser photolysis techniques were incorporated to obtain (1) the absorption spectra and coefficients of triplet vitamin K3 (2-methyl-1,4-naphthoquinone, MNQ) and its ketyl radical (2-methylnaphthosemiquinone, 2MNQH*) in acetonitrile (ACN) as well as to reveal (2) the mechanisms for hydrogen atom abstraction of triplet MNQ (3MNQ*) from phenol which proceeded in a diffusion process with an efficiency of unity. On the other hand, the hydroxymethylnaphthoxy radical was produced with the benzophenone ketyl radical (BPK) by the hydrogen atom transfer from triplet 2-methyl-1,4-dihydroxynaphthalene (MDHNp) sensitized by triplet benzophenone to benzophenone (BP) via the triplet exciplex. The question to be addressed was, which was produced in the MDHNp-BP system, the 2-methyl or 3-methylnaphthosemiquinone radical? Comparing the absorption spectrum and coefficient of the radical produced via the triplet exciplex with those of the 2MNQH* obtained by H-atom abstraction of 3MNQ*, the radical formed with BPK was revealed to be 2MNQH*. The reasons for the preferable formation of 2MNQH* are discussed for H-atom abstraction as well as the transfer reactions. 相似文献
17.
Time-resolved measurements of the electric-field-induced change in fluorescence intensity have been made for methylene-linked compounds of pyrene and N,N-dimethylaniline (DMA) doped in a polymer film. The lifetime of the fluorescence emitted from the locally excited state of pyrene chromophore becomes shorter in the presence of electric field (F), when the dopant concentration is high. The lifetime of the excipelx fluorescence resulting from the photoinduced electron transfer (PIET) from DMA to the excited state of pyrene chromophore between different molecules also becomes shorter in the presence of F. Based on the simulation of the electric field effect on fluorescence decay, the mechanism of intermolecular PIET between DMA and pyrene chromophore in a polymer film is discussed. 相似文献
18.
Recombination radiation in tetracene crystal is shown to be modified by the application of a magnetic field. Relative variations of radiation intensity with field and orientation can be explained in terms of molecular singlet fission and triplet exciton-charge carrier interaction. 相似文献
19.
Verhoeff AA Otten RH van der Schoot P Lekkerkerker HN 《The Journal of chemical physics》2011,134(4):044904
We investigate the effect of a magnetic field on the shape and director field of nematic droplets in dispersions of sterically stabilized and charge-stabilized colloidal gibbsite platelets with a negative diamagnetic anisotropy. Depending on the magnetic field strength and tactoid size, we observe with polarized light microscopy several interesting structures, with different shapes and director fields both with and without defects. In particular, our findings provide the first experimental evidence for the existence of the split-core defect structure predicted ten years ago by Mkaddem and Gartland [Phys. Rev. E 62, 6694 (2000)]. The split-core structure is a metastable director-field configuration that can be stabilized by a sufficiently strong externally applied magnetic field but only if the diamagnetic anisotropy of the particles is negative. To account for our observations, we present a calculation of the stability regions of different shapes and director-field structures as a function of tactoid size, anchoring conditions, surface tension, elastic constants, and magnetic field strength. By fitting the experimental data to the theoretically predicted structures, we are able to extract values for the splay elastic constant, interfacial tension, and anchoring strength. Remarkably, we find significant differences between the two systems studied: for sterically stabilized gibbsite in bromotoluene the anchoring strength is one order of magnitude larger than that of aqueous gibbsite, with the latter exhibiting weak and the former strong anchoring of the director field to the interface. The splay elastic constants that we obtain are in agreement with earlier experiments, simulations, and theory, while the interfacial tension and anchoring strength are considerably larger than what was found in earlier experiments. 相似文献
20.
《Chemical physics》1987,118(2):199-209
The full quantal theory of heavy-particle collisions in the presence of a static magnetic field, B, has been formulated. A new mechanism of magnetic field effect was found which depends on the velocity of the molecular center of mass and plays an important role at high-speed collisions. A power series expansion of the cross section as a function of B was obtained, which can be applied to collisions at weak field. It was also found that the differential cross section can become zero due to the magnetic field when a rovibronic energy level of a molecule is in resonance with another energy level. 相似文献