Topic
Excimer
About: Excimer is a research topic. Over the lifetime, 3725 publications have been published within this topic receiving 75104 citations.
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TL;DR: A simple-structured molecule L1, a diethylenetriamine bearing two end pyrene fragments, demonstrates triple-mode fluorescence consisting of monomer and short- and long-lived excimer emissions in water, which are precisely controlled by pH and an addition of a less-polar organic solvent.
76 citations
TL;DR: It is concluded that at room temperature absorption of light can cause local “melting” of regular structures and thus, in some polymers, permit the attainment of a face‐to‐face arrangement of aromatic rings within the radiative lifetime of their excited singlet states.
Abstract: Previous fluorescence and phosphorescence studies of aromatic model compounds have been extended to polymers: “atactic” and isotactic polystyrene, seven aromatic poly-(amino acids), and two proteins. We have confirmed previous observations that both forms of polystyrene exhibit strong excimer fluorescence emission at room temperature but not at 77°K. Of the poly(amino acids) (all observed in helix-supporting solvents), poly-L-phenylalanine, poly(α-benzyl-L-aspartic acid), and poly-1-benzyl-L-histidine likewise show excimer emission at room temperature but not at 77°K., while poly-L-tyrosine, poly-L-tryptophan, poly(γ-benzyl-L-glutamic acid), and poly-S-benzyl-L-cysteine exhibit no excimer emission at either temperature. The aromatic residues of bovine serum albumin exhibit only “normal” fluorescence, but, lysozyme appears to be unique among proteins in showing excimer-like tryptophan emission in the native state; its luminescence becomes “normal” upon denaturation. It appears very probable that none of these polymers has a ground-state conformation in which the aromatic groups have face-to-face orientations appropriate for excimer interaction. It is concluded that at room temperature absorption of light can cause local “melting” of regular (usually helical) structures and thus, in some polymers, permit the attainment of a face-to-face arrangement of aromatic rings within the radiative lifetime of their excited singlet states. In certain other polymers (for reasons not clear at present), and in all polymers at 77°K., this does not occur. This concept is extended to provide a bettor basis for understanding the mechanism of formation of the photodimer of thy mine in irradiated DNA.
76 citations
TL;DR: In this article, the authors measured the extent of adiabatic and nonadiabatic dissociation for different vibrations in the electronically excited state and showed that the kinetic energy release distribution is qualitatively similar to the ones from dissociation of ammonia excited to the electronic origin or to several different levels of bending vibration and umbrella vibration.
Abstract: Velocity map ion imaging of the H atoms formed in the photodissociation of vibrationally excited ammonia molecules measures the extent of adiabatic and nonadiabatic dissociation for different vibrations in the electronically excited state. Decomposition of molecules with an excited symmetric N–H stretch produces primarily ground state NH2 along with a H atom. The kinetic energy release distribution is qualitatively similar to the ones from dissociation of ammonia excited to the electronic origin or to several different levels of the bending vibration and umbrella vibration. The situation is very different for electronically excited molecules containing a quantum of antisymmetric N–H stretch. Decomposition from that state produces almost solely electronically excited NH2*, avoiding the conical intersection between the excited state and ground state surfaces. These rotationally resolved measurements agree with our previous inferences from lower resolution Doppler profile measurements. The production of NH2*...
76 citations
TL;DR: In this article, a review of gas-phase electronic energy transfer processes for excited atoms with sufficient energy to yield electronically excited products in encounters with other atoms or molecules is presented, focusing on excited states that result from orbital excitation rather than low-energy spin-orbit states that have the same electronic configuration as the ground state.
Abstract: Gas-phase electronic energy transfer processes are reviewed for excited atoms with sufficient energy to yield electronically excited products in encounters with other atoms or molecules. Attention is focused on excited states that result from orbital excitation rather than low-energy spin-orbit states that have the same electronic configuration as the ground state. 281 references (GHT)
76 citations
TL;DR: The structural basis of selective excimer formation in the presence of Ag(+) ions presents a viable approach for ratiometric detection of these ions.
Abstract: This Communication describes a novel adenine−pyrene conjugate (1) and its solid-state structure with silver and copper ions. Single-crystal studies of metal complexes of 1 offer insight into molecu...
75 citations