Singlet polymers

Black, as internal filter regarding ultra-violet light [42], is used with high efficiency. Besides, since black usually contains stable free radicals, it may react with photochemically formed active polymer centres, in such a way reducing the rate of the process of chain continuation [62], Black is also used as suppressor of triplet and singlet polymer states. 

Monomer (Section 6 21) The simplest stable molecule from which a particular polymer may be prepared Monosaccharide (Section 25 1) A carbohydrate that cannot be hydrolyzed further to yield a simpler carbohydrate Monosubstituted alkene (Section 5 6) An alkene of the type RCH=CH2 in which there is only one carbon directly bonded to the carbons of the double bond Multiplicity (Section 13 7) The number of peaks into which a signal IS split in nuclear magnetic resonance spectroscopy Signals are described as singlets doublets triplets and so on according to the number of peaks into which they are split... 

Hindered amines, such as 4-(2,2,6,6-tetramethylpiperidinyl) decanedioate, serve as radical scavengers and will protect thin Aims under conditions in which ultraviolet absorbers are ineffective. Metal salts of nickel, such as dibutyldithiocarbamate, are used in polyolefins to quench singlet oxygen or elecbonically excited states of other species in the polymer. Zinc salts function as peroxide decomposers. 

The peaks centered at 5 = 1.84 ppm-a singlet in the syndiotactic and a quartet in the isotactic polymers-are thus identified with these protons. This provides an unambiguous identification of the predominant stereoregularity of these samples. 

The NMR spectrum of the polymer 14.16 shows two singlets of approximately equal intensities that differ in chemical shift by only 0.17 ppm. This observation is attributed to the formation of equal amounts of isotactic (14.16a, both S=0 groups on the same side of the polymer chain) and syndiotactic (14.16b, S=0 groups on opposite sides of the polymer chain) forms of the polymer. The atacticity is confirmed by the H and NMR spectra. Two resonances are observed for the McaP groups of 14.16a, whereas 14.16b gives rise to only one resonance. 

B. Ranby and J. F. Rabek (eds.) Singlet Oxygen Reactions with Organic Compounds and Polymers, Wiley, Chichester, 1978, 331 pp. 

PM spectra and their decays in DOO-PPV films and dilute solutions, we conclude that the primary excitations in DOO-PPV films are also singlet excitons [26]. The long excitonic lifetime and a corresponding high PL quantum efficiency [27] indicates that DOO-PPV is a high quality polymer material, which is very suitable for electrooptics and laser action applications [28],... 

Conjugated polymers are centrosymmetric systems where excited states have definite parity of even (A,) or odd (B ) and electric dipole transitions are allowed only between states of opposite parity. The ground state of conjugated polymers is an even parity singlet state, written as the 1A... PM spectroscopy is a linear technique probing dipole allowed one-photon transitions. Non linear spectroscopies complement these measurements as they can couple to dipole-forbidden trail-... 

We assume that standard Coulomb-correlated models for luminescent polymers [11] properly described the intrachain electronic structure of m-LPPP. In this case intrachain photoexcitation generate singlet excitons with odd parity wavefunctions (Bu), which are responsible for the spontaneous and stimulated emission. Since the pump energy in our experiments is about 0.5 eV larger than the optical ran... 

A critical parameter in determining the operating efficiency of polymer LEDs is the luminescence quantum efficiency of singlet excilons in the polymer i.e. the probability that a singlet exciton will decay radiatively. The luminescence quantum elft-... 

Spectral Transparence Starting from 230 nm HN—< CH3 4-Toluidino p-Naphthoxy Substituent Photoactive from the First Excited Singlet State Polymers Photochemically Active from the First Excited Singlet State of the Phosphorus Substituents - " - "... 

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