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Showing papers on "Excimer published in 1983"


Journal ArticleDOI
TL;DR: Four-level laser energy level schemes are compared from the mechanistic spectroscopic viewpoint and the lasing action of the chlorophyll special pair and other molecules is discussed as an example of an intramolecular proton-transfer laser.
Abstract: Four-level laser energy level schemes are compared from the mechanistic spectroscopic viewpoint: (i) noble-gas excimer, (ii) solution molecular excimer, (iii) conventional dye laser, and (iv) intramolecular proton transfer. The lasing action of the chlorophyll special pair is discussed as an example of a solution excimer laser, and the lasing action of 3-hydroxyflavone and other molecules is discussed as an example of an intramolecular proton-transfer laser.

117 citations


Book ChapterDOI
TL;DR: In this article, the authors focus on the chemistry of excited complexes and the maximum rate for the process is determined by the rate constant for diffusion control in the solvent employed, which is a function of the number of collisions that must occur within the lifetime of the excited state.
Abstract: Publisher Summary This chapter focuses on the chemistry of excited complexes. The term exciplex (excited complex) is used to describe an electronically excited molecular complex of definite stoichiometry. Complexes falling into this broad classification include excimers (excited dimers) (electronically excited complexes formed between identical atoms or molecules), heteroexcimers (electronically excited complexes formed between two non identical atoms or molecules), and excited charge-transfer complexes (complexes produced by excitation of ground state molecular complexes for which there is conclusive evidence for association in the ground state). The formation of intermolecular complexes in fluid solution requires that after excitation of one of the partners, collision with the other partner must occur within the lifetime of the excited state. The maximum rate constant for the process is determined by the rate constant for diffusion control in the solvent employed.

108 citations



Journal ArticleDOI
TL;DR: In this article, a single excimer laser was used to pump a dye laser generating a single ps pulse at twice the excimer wavelength and to amplify the frequency-doubled pulse to high peak powers.

60 citations


Journal ArticleDOI
TL;DR: The first lifetime measurements of DNA fluorescence are reported and a post-pulse exponentially decaying emission has been observed with a lifetime of 2.9 +/- 0.3 ns; this is most likely an excimer fluorescence.

53 citations


Journal ArticleDOI
TL;DR: In this paper, the phase separation behavior of double-chain ammonium amphiphiles was investigated in the presence and absence of phase transition phenomena, and it was shown that the excimer emission disappears by phase transition to the rigid (crystalline) bilayer.
Abstract: The benzene chromophore contained in double-chain(hydrocarbon) ammonium amphiphiles gives both of monomer and excimer fluorescence in the fluid(liquid crystalline) bilayer organization. The excimer emission disappears by phase transition to the rigid(crystalline) bilayer. In contrast, the corresponding fluorocarbon bilayer, in the absence of phase transition phenomena, shows excimer emission at all temperatures(15–50 °C). The excimer emission decreases when these probe amphiphiles are diluted in matrix bilayers. These results are applied to study the phase separation behavior of hydrocarbon and fluorocarbon bilayer membranes. The fluorocarbon bilayer is not extensively miscible with the hydrocarbon bilayer, and vice versa. The miscibility is influenced additionally by the chemical structure of amphiphiles. The rate of mixing is determined by the component miscibility as well as by the aggregate morphology. The DSC study supports these conclusions and further indicates that an unsymmetrical, double-chain (...

51 citations


Journal ArticleDOI
TL;DR: In this paper, the emission properties of styrene oligomers from dimer to tridecamer were investigated by picosecond pulse radiolysis at room temperature, and it was shown that there is a discrepancy between the results of photostationary measurements with those of transient methods.
Abstract: The emission properties of styrene oligomers from dimer to tridecamer have been investigated by picosecond pulse radiolysis at room temperature. The oligomers are precisely fractionated and are considered to be models of atactic polystyrene. The rate constant for excimer formation kDM of the order of 108 s−1, increases with increasing number of monomer units n for 2≤n≤8, then levels off at the value for polystyrene. The rate constant for singlet energy migration between adjacent chromophores in polystyrene was determined to be 3×1010 s−1 (∼30 ps). An average time of 7.2 ns was found to be necessary for two adjacent chromophores to assume the excimer conformation (g−t or tg− in a racemo dyad; tt in a meso dyad) from their initial equilibrium distribution of conformations. The present result is an indication that one may investigate the dynamics of internal rotation by photophysical techniques. Moreover, from a comparison of the results of photostationary measurements with those of transient methods, it is found that there is a discrepancy between them. This discrepancy is assumed to be caused by a molecular weight dependence either of the rate constant for the radiative deactivation from the excited monomer singlet kFM or of intramolecular self‐quenching.

37 citations


Patent
Kantilal Jain1, Carlton G Willson1
07 Jun 1983
TL;DR: In this article, an optical lithography method and apparatus in which a pulsed excimer laser produces at least one fundamental output which is directed to expose a photosensitive medium is presented.
Abstract: An optical lithography method and apparatus in which a pulsed excimer laser produces at least one fundamental output which is directed to expose a photosensitive medium. The output is highly non-gaussian and has sufficient power so that full exposures can be accomplished within a few seconds. An alternate light source is provided by directing the excimer laser output to a Raman cell having a suitable Raman medium contained therein. At least one secondary wavelength is produced by stimulated Raman scattering and the output of the Raman cell is directed to expose a photosensitive medium. A mixture of more than one excimer gas can also be provided in the excimer laser to produce one fundamental output for each excimer gas present in the mixture. These outputs can be directed to expose a photosensitive medium directly. Alternatively, these outputs can be directed to a Raman cell having either a single Raman medium or multiple Raman media in a suitable mixture and directing the output from the Raman cell to expose the photosensitive medium.

34 citations



Journal ArticleDOI
TL;DR: In this paper, the potential energy curves of the argon excimer that arise due to excitation to the 4s and 4p Rydberg molecular orbitals were computed and compared with those previously computed.
Abstract: Configuration interaction calculations are reported for the potential energy curves of the argon excimer that arise due to excitation to the 4s and 4p Rydberg molecular orbitals. Effective core potentials were employed to replace the core electrons of the Ar atoms thereby reducing the computational procedure to one for a 16 valence system. Potential energy curves for three excimer states of each of the symmetries 1Σ+g, 1Σ+u, 3Σ+g, 3Σ+u, 1Πu, 3Πu, 1Πg, and 3Πg are reported and compared with those previously computed. Spectroscopic constants and curve maxima are reported where appropriate.

30 citations


Journal ArticleDOI
TL;DR: In this paper, the pyrene monomer-excimer system was studied under oxygen-free conditions on silica and silylated silica in the loading range 2 −200 μmole pyrene/g oxide.

Book
01 May 1983

Journal ArticleDOI
TL;DR: In this paper, Walker et al. demonstrated that the unusual long-wavelength shift and bandwidth of the fluorescence spectra of 7-azaindole in alcohol and water solutions compared with hydrocarbon solution is the result of exciplex formation between the 7-aza-nole and the hydroxylic solvent molecules.
Abstract: The unusual long-wavelength shift and bandwidth of the fluorescence spectra of 7-azaindole in alcohol and water solutions compared with hydrocarbon solution is demonstrated to be the result of exciplex formation between the 7-azaindole and the hydroxylic solvent molecules. The technique of monitoring the fluorescence band position, intensity, and half-width (fwhm) in alcohol-hydrocarbon solutions as developed by Walker et al. has been used to distinguish the exciplex model from other existing models. Aggregation effects and the dependence of the exciplex fluorescence yield on alcohol acidity have led to a model attributing excited-state charge transfer between the nonbonding oxygen electrons in the alcohol and the lowest vacant ..pi.. orbital of excited 7-azaindole. It also has been demonstrated that excited-state double proton transfer between 7-azaindole and a single alcohol molecule occurs, independent of the exciplex formation, for molecules that form a cyclic hydrogen-bonded complex in the ground state.

Journal ArticleDOI
TL;DR: In this paper, the addition of 1-borneol caused a decrease in the excimer emission as a result of replacement of the included naphthalene by 1-boundedol.
Abstract: γ-Cyclodextrin appended by a naphthalene moiety forms an excimer with naphthalene in its cavity. The addition of 1-borneol causes a decrease in the excimer emission as a result of replacement of the included naphthalene by 1-borneol.

Journal ArticleDOI
01 Jan 1983-Polymer
TL;DR: In this paper, the authors investigated the excimer/monomer fluorescence ratio and activation energy for 10,10′-diphenyl-bs-9-anthrylmethyloxide (diphant) in bulk poly(dimethylsiloxanes) from −40°C to 160°C.




Journal ArticleDOI
TL;DR: In this article, a charge transfer process can be intermolecular, involving an excited molecule and a neighboring molecule, one serving as an acceptor and the other serving as a donor molecule, or intramolecular involving a charge redistribution in the excited molecule.
Abstract: A primary mechanism of energy relaxation and chemical change in organic molecules in excited electronic states is charge transfer. 1 The charge transfer process can be intermolecular, involving an excited molecule and a neighboring molecule, one serving as an acceptor and the other as a donor molecule, or intramolecular, involving a charge redistribution in the excited molecule which produces a very large excited state dipole moment.In our investigations of the dynamics of these various charge transfer processes, a picosecond laser pulse was used to excite the molecules of interest. The charge transfer dynamics were monitored by a variety of techniques, including transient absorption of the excited charge transfer complex (exciplex) or ion radicals by a time delayed picosecond pulse, and fluorescence from the exciplex and from the initially excited molecule using a picosecond streak camera for detection.

Journal ArticleDOI
TL;DR: In this paper, the absorption spectra of N-ethyl carbazole, 1,3-di(N-carbazolyl) propane, meso (d¢)-2,4-di (N- carbazolyls) pentane and poly(Nvinylcarbazole) in the excited singlet state were measured in solution by a picosecond Nd 3+ : YAG laser photolysis method.

Journal ArticleDOI
TL;DR: In this paper, associative interactions of several cationic probes, with anionic polyelectrolytes, with a neutral polymer, poly(ethy 1ene oxide) (PEO), have been investigated by fluorescence techniques.
Abstract: The associative interactions of several cationic probes, Le., bis(a-naphthylmethy1)a”onium chloride (DNMAC), (a-naphthylmethy1)a”onium chloride (NMAC), dibenzylammonium chloride (DBAC), and (benzy1)a”onium chloride (BAC), with anionic polyelectrolytes, Le., sodium poly(ethy1enesulfonate) (PES), sodium poly(styrenesulfonate) (PSS), and sodium poly(2-acrylamido-2-methyl-l-propanesulfonate) (PAMPS), and with a neutral polymer, poly(ethy1ene oxide) (PEO), have been investigated by fluorescence techniques. Evidence is presented that the probe conformation in both the ground and the excited singlet states depends on the type of interaction (hydrophobic or electrostatic) that dominates in determining the binding strength. For example, the predominately hydrophobic binding of DNMAC and PEO in aqueous solution produces a decrease in the ratio of excimer to monomer emission of the probe, relative to that in aqueous solution. The predominately electrostatic binding of DNMAC and PAMPS in methanol produces a sharp increase in the ratio of excimer to monomer emission of the probe relative to that of the probe in methanol solution. The binding of the probes to the polyelectrolytes PAMPS, PSS, and PES in aqueous solution results in an enhancement of excimer emission of the probe. The dependence of such enhancement of the excimer emission on the probe and/or polyelectrolyte concentration suggests that, in spite of the low effective charge of the probes, electrostatic interactions of the probe and the polyelectrolyte are not negligible with respect to the hydrophobic interactions.

Journal ArticleDOI
TL;DR: A crystalline quartz flow cell was developed for simultaneous fluorescence, photoacoustic effect, and two-photon photoionization detection of aromatic compounds in HPLC eluents as discussed by the authors.
Abstract: A crystalline quartz flow cell has been developed for simultaneous fluorescence, photoacoustic effect, and two-photon photoionization detection of aromatic compounds in HPLC eluents Excimer laser-excited three mode detection of naphthalene, 7,8-benzoflavone, N-ethylcarbazole, and anthracene in 70/30 v/v acetonitrile/water is exhibited The flow cell is suitable for use with deoxygenated solvent systems and is orientation independent

Journal ArticleDOI
TL;DR: Using a mode-locked Nd 3+ : YAG laser and a streak camera, the formation process of excimers in poly(N-vinylcarbazole) film was directly measured to be quite rapid as mentioned in this paper.


Journal ArticleDOI
TL;DR: In this paper, the influence of inhomogeneity of the gas density in the pulse-periodic regime on the average power of an excimer laser was investigated and the experimental results agreed qualitatively with the proposed model.
Abstract: An investigation was made of the influence of inhomogeneity of the gas density in the pulse-periodic regime on the average power of an excimer laser. The experimental results agreed qualitatively with the proposed model. An average power of ~130 W was obtained from a pulse-periodic XeCl excimer laser at a repetition frequency of ~500 Hz.

Journal ArticleDOI
TL;DR: In this article, the first excited singlet state (singlet b(1u) of naphthalene in cyrogenic molecular hydrocarbon alkane and alkene liquids (CH4, C2H4 and C3H8) has been obtained and discussed in terms of solute solvent intermolecular interaction.
Abstract: : Optical spectra of the first excited singlet state (singlet b(1u)) of naphthalene in cyrogenic molecular hydrocarbon alkane and alkene liquids (CH4, C2H4, C2H6, C3H6, C3H8, 1-C4-H8) have been obtained and are discussed in terms of solute solvent intermolecular interaction. Data include gas to liquid shifts, Franck-Condon shifts, line widths for absorption and emission, and their temperature depencence. Naphthalene line widths and their temperature dependences and Franck-Condon shifts are smaller than those found by benzene but the gas to liquid shifts for both systems are quite similar. Based on these results and the comparison with similar benzene data, the ground and excited state Lennard-Jones type potential curves for naphthalene/solvent interactions can be generated. The main conclusions ar ethat naphthalene has a stronger interaction with the solvent than does benzene, the interaction scales with solvent polarizability, and the change in cavity radius upon excitation is greater for benzene for the naphthalene. Lifetime data have also been obtained for the naphthalene fluorescence. At low temperature, the liquid state lifetime for fluorescence is roughly the same as that found in the low pressure gas (approx 300 ns). A small temeprature dependence is characterized for these low concentration solutions leading to an activation energy for naphthalene collision induced intersystem crossing of approx 100 per cm. The excimer formation and monomer regeneration mechanism reported for benzene is also observed in naphthalene C3H6 and C3H8 solutions but it is of much less importance to the overall kinetics. (Author)


Journal ArticleDOI
TL;DR: In this article, a delayed fluorescence S 2 → S 0 from the second excited singlet state (S 2 ) of 4,6,8 trimethylazulene (TMA), resulting from homo-triplet annihilation T 1 + T 1 ∼→ S 2 + S 0, has been observed.

Journal ArticleDOI
TL;DR: In this paper, the green excimer band (λ∼504 nm) of the iodine dimer has been observed in electron-beam-pumped mixtures of Ar (or Ne), and hydrogen iodide.
Abstract: Gain on the green excimer band (λ∼504 nm) of the iodine dimer has been observed in electron‐beam‐pumped mixtures of Ar (or Ne), and hydrogen iodide. A peak gain coefficient of γ>1.1% cm−1 is measured at 506 nm with a tunable dye laser and the full width at half‐maximum (FWHM) of the gain spectrum in Ar diluent is 13 nm. Temporally resolved gain and fluorescence measurements show that the green emission originates from an I2 ion pair state other than D′. However, strong collisional coupling between the upper states of the UV (λ=342 nm) and green bands and superfluorescence on the UV band (I342∼2 MW cm−2) appear to limit the green gain coefficient to <20% of its small‐signal value. Consequently, suppression of superfluorescence on the UV D′→A′ bands of the homonuclear halogens should lead to a new family of excimer lasers with wavelengths extending from the green into the ultraviolet.

Journal ArticleDOI
TL;DR: In this paper, both donor-acceptor and heteroexcimer-type exciplexes, formed between host and guest molecules, are found to be less repulsive than that of the pyrene excimer.