Showing papers on "Excimer published in 1967"
TL;DR: In this article, the fluorescence decay times of excimers of anthracene, perylene, pyrene and 1-methylnaphthalene have been studied in a rigid cyclohexane matrix of low temperatures.
52 citations
TL;DR: In this paper, a mixed excimer fluorescence is observed when any one of a variety of aromatic hydrocarbons is added to solutions of 9−cyanoanthracene or 9, 10−dicyanoanthracene.
Abstract: Mixed excimer fluorescence is observed when any one of a variety of aromatic hydrocarbons is added to solutions of 9‐cyanoanthracene or 9, 10‐dicyanoanthracene. The formation of a mixed excimer appears to be markedly dependent upon the ionization potential of the donor. The emission maxima of the 9, 10‐dicyanoanthracene mixed excimers vary linearly with the polarographic oxidation potentials of the donors, a results corresponding to that found for charge‐transfer absorption bands. It is concluded that charge‐transfer interaction is important in the excimer state.
36 citations
35 citations
TL;DR: In this article, a triplet-triplet association was proposed to produce the quintet, dissociated triplet, and singlet excimer states of pyrene pyrene.
31 citations
TL;DR: In this paper, the energy of the excimer luminescence is interpreted in terms of a simple Huckel-type dimer orbitals, which are constructed by treating the eximer as one species.
Abstract: The energy of the excimer luminescence is interpreted in terms of a simple Huckel-type dimer orbitals, which are constructed by treating the excimer as one species. The present model of the excimer yields results quite similar to those of the complicated ASMO CI treatment as developed earlier; further, it is capable of explaining various characteristics of the excimer, including the 6000 cm−1 rule.
19 citations
TL;DR: In this article, it was shown that trap species other than T1G are the reservoir for thermal excitation to the host exciton band T1H, and that the trap species may or may not be, but probably is not, a contaminant detected phosphorimetrically in the purified biphenyl material.
Abstract: Phosphorescence, fluorescence, delayed fluorescence, excimer fluorescence, and delayed excimer fluorescence of pyrene have been studied in a host biphenyl system. The delayed fluorescence and delayed excimer fluorescence are biexcitonic, have identical lifetimes at all temperatures and exhibit similar dependency of emission intensity on temperature; therefore, they both originate in identical kinetic events. These events involve thermal depletion of a trap of energy ∼1000 cm−1 less than the lowest energy host exciton triplet band and of lifetime ∼0.2 sec; this trap species may or may not be, but probably is not, a contaminant detected phosphorimetrically in the purified biphenyl material. It appears that trapping of the host triplet exciton occurs more efficiently at monomer pyrene sites than at nascent excimeric pyrene sites (regions, perhaps, of pyrene microcrystallinity). The excimer and delayed excimer fluorescence exhibit vibrational structure under certain circumstances; this structure is analyzable in terms of ag modes of the ground‐state monomeric pyrene. Those crystals which possess broad (i.e., unresolved) excimer spectra exhibit a distinct red shift of this spectrum as the temperature is decreased; this behavior is rationalized herein. The guest phosphorescence intensity and lifetime are more or less temperature‐independent; this behavior is quite characteristic of materials with large T1H—T1G bandgaps. Excitation spectra for all emissions are presented; it is shown thereby that trap species other than T1G are the reservoir whence thermal excitation to the host exciton band T1H proceeds. The thesis developed is that delayed excimer fluorescence and delayed fluorescence are produced by annihilation of a trap triplet and a guest triplet.Phosphorescence, fluorescence, delayed fluorescence, excimer fluorescence, and delayed excimer fluorescence of pyrene have been studied in a host biphenyl system. The delayed fluorescence and delayed excimer fluorescence are biexcitonic, have identical lifetimes at all temperatures and exhibit similar dependency of emission intensity on temperature; therefore, they both originate in identical kinetic events. These events involve thermal depletion of a trap of energy ∼1000 cm−1 less than the lowest energy host exciton triplet band and of lifetime ∼0.2 sec; this trap species may or may not be, but probably is not, a contaminant detected phosphorimetrically in the purified biphenyl material. It appears that trapping of the host triplet exciton occurs more efficiently at monomer pyrene sites than at nascent excimeric pyrene sites (regions, perhaps, of pyrene microcrystallinity). The excimer and delayed excimer fluorescence exhibit vibrational structure under certain circumstances; this structure is analyzable...
17 citations
TL;DR: The difference in the absorption spectra of adenine and thymine is used to show that at 80°K light absorbed by either of these bases in poly dAT leads to an excimer singlet state and to the triplet state of thymine.
16 citations
TL;DR: In this article, the fluorescence spectra and relative quantum yields of ethyl and iso-propyl benzene and ortho, meta, and para -xylene in hexane and in the liquid phase were observed as a function of concentration and temperature from 20°C down to the freezing point of the liquid.
15 citations
TL;DR: In this article, the exciton resonance state originating from the molecular 1Bb state was shown to form a bound excimer state in anthracene, pentacene, 1,2-benzanthracene and 3,4-benzphenanthrene and triphenylene.
11 citations
TL;DR: From observations and analysis of the pyrene crystal excimer fluorescence spectra from 4°K to 353°K, the excimer interaction potential V′ = 51 330 − (1.136 × 106)/r3 (cm−1) has been determined as a function of the intermolecular separation as mentioned in this paper.
11 citations
TL;DR: In this article, a long-lived emission of acriflavine absorbed into a polyvinyl alcohol sheet has been investigated, and a new, previously-unobserved emission band has been observed.
Abstract: A long-lived emission of acriflavine absorbed into a polyvinylalcohol sheet has been investigated. At higher concentrations, a new, previously-unobserved emission band has been observed. It has been shown that the newly-observed band can be interpreted by a mechanism in which the thermal excitation of the triplet state to the excimer state takes place, followed by an emission. The term “delayed thermal excimer fluorescence” has been given to specify the emission of this type.
01 Jan 1967
TL;DR: In this paper, the prediction of ground, ionized, and excited states of unknown nitrogen fluoride molecule using quantum mechanics has been studied in the context of quantum mechanics of molecules and their properties.
Abstract: Quantum mechanical study of molecules - prediction of ground, ionized, and excited states of unknown nitrogen fluoride molecule