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Journal ArticleDOI

Quadrupole Resonance Spectrum of Chloranil and Its Hexamethylbenzene Complex

01 Jun 1960-Journal of Chemical Physics (American Institute of Physics)-Vol. 32, Iss: 6, pp 1882-1883
TL;DR: The nuclear quadrupole resonance spectrum of chloranil and in the 1: 1 complex with hexamethylbenzene was obtained at 77 tained K and room temperature.
Abstract: The nuclear quadrupole resonance spectrum of Cl in chloranil and in the 1: 1 complex of chloranil with hexamethylbenzene was obtained at 77 tained K and room temperature. The results are used to estimate the upper limit for charge transfer in the complex from chloranil to hexamethylbenzene. Complexes of picrylchloride: hexamethylbenzene and parachloroaniline: sym-trinitrobenzene were also studied but no resonances were detected. (D. L.C.)
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Journal ArticleDOI
TL;DR: In this paper, the halogen pure electrical quadrupole resonance frequencies have been measured in the three 1:1 complexes, CBr4·p−xylene, CCl4· p−p xylene, and Br2·benzene, and it was concluded that little if any charge transfer exists in the ground state of these complexes.
Abstract: Halogen pure electrical quadrupole resonance frequencies have been measured in the three 1:1 complexes, CBr4·p‐xylene, CCl4·p‐xylene, and Br2·benzene. From an examination of the measured frequencies of the complexes and the halogen‐containing compounds (CBr, CCl4, and Br2) together with information from the x‐ray structure determinations for two of the complexes, it has been concluded that little if any charge transfer exists in the ground state of these complexes.

53 citations

Journal ArticleDOI
TL;DR: In this paper, the phase transition in chloranil crystal has been studied by measurements of the 35Cl nuclear quadrupole resonance frequency and the spin-lattice relaxation time.
Abstract: The phase transition in chloranil crystal has been studied by measurements of the 35Cl nuclear quadrupole resonance frequency and the spin‐lattice relaxation time. The splitting of the resonance line in the low temperature phase was shown to behave as an order parameter of the phase transition. The experimental order parameter and the anomalous behavior of the transition probability (1/T1) near the transition point were interpreted satisfactorily in terms of the librational soft‐mode theory which assumes anharmonic coupling between molecular librational modes in the crystal.

30 citations

Journal ArticleDOI
TL;DR: In this paper, the nuclear quadrupole resonance of Cl35 and its Zeeman effect have been observed in chloranil between 78° and 373°K and a broad phase transition centered near 100°K is examined.
Abstract: The nuclear quadrupole resonance of Cl35 and its Zeeman effect have been observed in chloranil between 78° and 373°K. Effects of thermal expansion appear negligible hence the Bayer theory is used with the measured temperature dependence of the pure quadrupole frequencies and the field‐gradient asymmetries to yield room‐temperature rigid‐body libration amplitudes of 〈θx2〉 = 18×10—3 rad2, 〈θy2〉 = 〈θz2〉 = 0, where x is along the molecular normal. A broad phase transition centered near 100°K is examined. The results suggest that the potential well V(θx) has a double minimum and that the transition occurs when the molecules have sufficient torsional energy to override the barrier.

29 citations

Journal ArticleDOI
TL;DR: In this paper, the EPR spectrum of a free trapped in single crystals of chloranil changes its phase from absorption to emission when the crystal is illuminated by visible light, and the time evolution of EPR signal is discussed in terms of the interaction between the doublet species and triplet excitons produced by light excitation.

23 citations

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