Showing papers on "Excimer published in 1982"
TL;DR: In this article, a KrF excimer laser was used for photoetching of polymethyl methacrylate (PMMA) for pulsed high power UV light, and the experimental results show that high power excimer lasers are the effective light source for UV photo-etching.
Abstract: Photoetching of polymethyl methacrylate (PMMA) for pulsed high power UV light is demonstrated. As a high power UV light source, a KrF excimer laser was used. Etching depth obtained by deep UV light irradiation has not only energy dependence, but also power dependence. It increased abruptly by increasing the exposed power density for the same exposed energy density.These experimental results show that high power excimer lasers are the effective light source for UV photoetching of PMMA.
291 citations
TL;DR: In this paper, the 2-methoxynaphthalene-β-cyclodextrin (CDx) and 2-naphthalenes-o-dicyanobenzene (DB) inclusion compounds in aqueous solution were studied by means of absorption and fluorescence spectra.
Abstract: Inclusion compounds in the systems naphthalene–β-cyclodextrin (CDx) and 2-methoxynaphthalene (MN)–o-dicyanobenzene (DB)–β-cyclodextrin in aqueous solution were studied by means of absorption and fluorescence spectra. In the former system a naphthalene excimer fluorescence was observed. By the analyses of the concentration dependence of the absorption spectra and the excimer fluorescence intensities, the species responsible for the excimer fluorescence is identified as a 2:2 inclusion compound which is formed by association of two 1:1 naphthalene–CDx inclusion compounds, not a 2:1 inclusion compound in which two naphthalene molecules enter into the cavity of one CDx molecule. In the latter system, absorption and fluorescence spectra due to a charge transfer complex of MN with DB were observed. By analyses similar to the naphthalene case, the existence of a 1:1:2 association compound formed between a MN–CDx inclusion compound and a DB–CDx inclusion compound is confirmed. Fluorescence quenching by I− and IO3...
232 citations
TL;DR: Human erythrocyte ghost membranes have been investigated using two intramolecular excimer probes, di( 1-pyrenyl)propane and di(1- pyrenylmethyl) ether, and the polarizability of the probe surroundings can be determined, leading to a surprisingly high value for the apparent refractive index.
85 citations
TL;DR: Fluorescence phase shift and demodulation methods were used in the analysis of excited-state reactions and to investigate solvent relaxation around fluorophores in viscous solvents to test the theoretical predictions and illustrate the characteristic features of phase-modulation data expected from samples which display time-dependent spectral shifts.
81 citations
TL;DR: Intramolecular excimer formation with 1,3-di(1-pyrenyl)propane was used to probe the fluidity of sarcoplasmic reticulum (SR) membranes where the probe could be incorporated (in a probe/lipid molar ratio of 1/2000 or less) without inducing any detectable damage.
Abstract: Intramolecular excimer formation with 1,3-di(1-pyrenyl)propane was used to probe the fluidity of sarcoplasmic reticulum (SR) membranes where the probe could be incorporated (in a probe/lipid molar ratio of 1/2000 or less) without inducing any detectable damage. The temperature was varied between -1 and 40 degrees C. The fluidity of the native SR membrane changes from 52 cP at 40 degrees C to 325 cP at 5 degrees C. The native SR membranes are less fluid than liposomes prepared from total membrane lipids. The fluidity of membranes reconstituted from the SR ATPase and a total lipid extract of the SR depends on the lipid/protein molar ratio and sharply decreases when this ratio becomes lower than 44, for all temperatures studied. This is in accord with literature reports describing the occurrence of approximately 30 lipid molecules around the Ca-ATPase molecule in the SR membrane. Arrhenius plots of the excimer to monomer fluorescence intensity ratio in native and reconstituted SR membranes display a break at about 20 degrees C which is not observed when the lipid/protein ratio is lower than 44. This break is interpreted as being a characteristic of the lipid portion of the membrane.
61 citations
TL;DR: In this paper, the luminescence behavior of a liquid crystal, dodecylcyanobiphenyl, as a function of temperature was investigated and the results were interpreted in terms of singlet monomer and excimer formation.
55 citations
TL;DR: In this paper, the authors used time-resolved fluorescence spectroscopy in the nanosecond and picosecond regimes to investigate the dynamics of excimer formation in α-perylene crystals.
55 citations
53 citations
TL;DR: In this paper, relative sputtering yields and velocity distributions for Ti sputtered by light ions have been measured, using He +, D + and H + ion bombardment at energies between 40 eV and 12 keV at normal incidence.
53 citations
52 citations
TL;DR: The results suggest that an intermediate involving the H3,H4 tetramer is formed first in nucleosome assembly, and a very fast transfer of histone pairs (probably H2A,H2B) can take place between partially reconstituted nucleosomes.
TL;DR: The fluorescence of pyrene has been measured in aqueous solutions in the presence of γ-cyclodextrin this article, indicating the formation of the 2:1 complex.
Abstract: The fluorescence of pyrene has been measured in aqueous solutions in the presence of γ-cyclodextrin. The excimer emission of pyrene was enhanced upon addition of γ-cyclodextrin, indicating the formation of the 2:1 complex of pyrene with γ-cyclodextrin which degraded upon addition of n-butyl alcohol to yield the more stable three-component complex of pyrene, n-butyl alcohol, and γ-cyclodextrin.
TL;DR: In this article, a series of diphenyl polyenes were investigated and the S1 state was assigned as a 1Ag state, in agreement with results from two-photon spectroscopic studies.
Abstract: Calculated and observed excited singlet state absorption (Sn←S1) spectra of a series of diphenylpolyenes are presented. In diphenyloctatetraene and diphenylhexatriene, the S1 state is assigned as an 1Ag state, in agreement with results from two‐photon spectroscopic studies. In diphenylbutadiene, we assign the S1 state as a 1Bu, although two‐photon studies have indicated that 1Ag state lies slightly below the 1Bu. It appears that a 1Ag state is the lowest excited state of diphenylbutadiene in its ground state geometry, but when the excited states relax to their equilibrium configurations, the 1Bu becomes the S1. Good agreement between the PPP–CI calculations and experimental Sn←S1 spectra demonstrates the potential usefulness of this technique in assigning ππ* excited states of large molecules.
TL;DR: In this paper, the excimer formation between pyrenes attached to the ends of a poly(ethyleneoxide) sample of nominal molecular weight 9600 has been examined in twelve solvents.
Abstract: Intramolecular excimer formation between pyrenes attached to the ends of a poly(ethyleneoxide) sample of nominal molecular weight 9600 has been examined in twelve solvents. In ten non-protic solvents the excimer to pyrene locally excited fluorescene intensity ratio IE/IM is inversely proportional to solvent viscosity, as expected for a diffusion-controlled process. Similar results were obtained for 〈k1〉 values obtained from flash-photolysis studies, where 〈k1〉 is the average rate constant for end-to-end cyclization in the polymer. In water and methanol, the extent of excimer emission and the rate of intramolecular excimer emission and the rate of intramolecular excimer formation were substantially greater than one would infer on the basis of solvent viscosity alone.
TL;DR: In this paper, an electronically excited tight complex (X s ) is proposed, of which only a small fraction rearranges to an excimer, and the quantum yield of excimer and triplet formation is wavelength dependent.
TL;DR: In this paper, lattice energy calculations on excited molecules in crystals, carried out using a simple centre-of-mass attractive excitation potential, are reported for two phases of anthracene, 9-cyanoanthracene and 9-methylanthracene.
TL;DR: In this paper, the authors used a Nd3+:phosphate glass laser and streak camera to measure the decay of the excited-state acceptor (anthracene moiety) and the fluorescence rise of the exciplex.
Abstract: Intramolecular charge transfer has been observed for the molecule anthracene-(CH,),-N,N-dimethylaniline (9- (3-(4-(dimethylamino)phenyl)propyl)anthracene) in nonpolar solvents of varying viscosities. The technique employed was picosecond time-resolved fluorescence utilizing a Nd3+:phosphate glass laser and streak camera. Measurements of the fluorescence decay of the excited-state acceptor (anthracene moiety) and the fluorescence rise of the exciplex demonstrate that there is no intermediate nonfluorescent state existing prior to exciplex formation and that the end-to-end cyclization of the four-bond methylene chain is exponential in time. This exponentiality has not been previously demonstrated. Furthermore, a dependence of exciplex rise time upon the fluorescence wavelength is found and interpreted as evidence for two distinct ground-state conformers, one being dominant. Each conformer has a different viscosity dependence for the formation of an exciplex. General conclusions concerning charge-transfer dynamics in solution are presented on the basis of these and related studies. Charge-transfer (CT) interactions of excited molecules with neighboring molecules play a vital role in electronic energy re- laxation. The quenching of excited-state fluorescence and either the appearance of a new, red-shifted exciplex emission or the formation of ion radicals are manifestations of charge-transfer phenomena. The widespread interest and importance of these light-driven charge generation processes is reflected by the nu- merous studies' on this subject since the discovery of the peryl-
TL;DR: In this article, a kinetic analysis of the main VUV emissions of the two gases allows a complete kinetic scheme of the transfer phenomena to be established, which leads directly or indirectly to the production of the 3P1 and 3P2 states of xenon which, through three-body heteronuclear collisions, are involved in the formation of the radiative Xe2* states responsible for the emission of the second continuum at 173 nm.
Abstract: For pt.I see ibid., vol.15, p.2935 (1982). Spectroscopic and kinetic study of ultraviolet emissions from argon-xenon mixtures brings to light very large energy transfers from argon and xenon. When small amounts of xenon (a few ppm) are added to argon, the argon continua disappear and simultaneously Xe resonance lines can be seen. At higher Xe concentrations (of the order of a few per cent), the spectra of mixtures are similar to those obtained in pure xenon. Kinetic analysis of the main VUV emissions of the two gases allows a complete kinetic scheme of the transfer phenomena to be established. Excited radiative xenon states are created from Ar2* molecules and atomic precursor states. The 1P1 state of xenon is excited by two-body collisions with the excimer Ar2*(3 Sigma u+) which is responsible for the second argon continuum (k=1.5*107 Torr-1 s-1). The transfer is also observed from the Ar*(3P1) state towards highly excited xenon levels (configuration 5f) (k=2.4*107 Torr-1 s-1). Both these paths lead, directly or indirectly, to the production of the 3P1 and 3P2 states of xenon which, through three-body heteronuclear collisions, are involved in the formation of the radiative Xe2* states responsible for the emission of the second continuum at 173 nm. The lifetime of this state, tau =106 ns, is not modified by the presence of argon.
TL;DR: The use of laser flash spectroscopic tecniques allows the detection, identification and dynamic analysis of biradicals and caged pairs in fluid solution at ambient temperatures.
TL;DR: In this article, the authors used the conformational energy of the naphthalene unit to explain the small formation rate for rac-2,4-di(2-naphthyl)pentane.
Abstract: Intramolecular excimer formation processes were explained by the conformational energy calculated by an empirical method. Observed rate constants of excimer formation processes are closely correlated to the fraction of tg conformation. This indicates that intramolecular excimers are mainly formed by the internal rotation, trans→gauche, with reference to the naphthalene unit. The fraction of the tg conformation, which is an adjacent conformation to the excimer conformation on the conformational energy map, serves as an effective concentration of the intramolecular reaction. The small formation rate for rac-2,4-di(2-naphthyl)pentane is due to the unfavorable rotational mode (g+\ightleftarrowsg−) required to take the excimer conformation.
TL;DR: In this paper, an evaluation of a XeCl excimer laser for the laser processing of Si is reported, and the annealing quality of ion-implantation damage, as measured by the crystalline perfection of the regrown layer and by p-n junction characteristics, is similar to that obtained with ruby or Nd:YAG lasers.
Abstract: An evaluation of a XeCl excimer laser for the laser processing of Si is reported. The annealing quality of ion-implantation damage, as measured by the crystalline perfection of the regrown layer and by p-n junction characteristics, is similar to that obtained with ruby or Nd:YAG lasers. However, the wide energy window between annealing and surface damage, the flat smooth surface obtained after laser irradiation, the capability of providing deep surface melting, and other features, indicate that XeCl and perhaps other excimer lasers is nearly ideal for semiconductor processing.
TL;DR: Supporting evidence is given for the argument that multiple fluorescence lifetimes are an intrinsic property of the pyrene derivatives and are not due to the presence of impurity or heterogeneity in the protein reaction sites.
TL;DR: It is found that, at pH 4, alpha-LA strongly interacts with the lipid bilayer, and these results agree with previously reported microcalorimetric, gel chromatographic, and fluorescence polarization studies.
Abstract: The nonconjugated bichromophoric molecule 1,3-di(1-pyrenyl)propane shows, besides the pyrene monomer fluorescence, a structureless emission due to an intramolecular excited dimer (excimer). In the case of intramolecular excimer forming systems, the ratio of the emission intensities of excimer vs. monomer (IE/IM) is sensitive to changes in membrane structure as will be illustrated here. The present molecule is a useful probe to report on lipid-protein interactions, at least in our model system. We have introduced it into the hydrocarbon layer of dimyristoylphosphatidylcholine vesicles in order to study their interaction with alpha-lactalbumin (alpha-LA) as a function of pH and temperature. On the basis of steady-state fluorescence, kinetic, and energy transfer studies, we have found that, at pH 4, alpha-LA strongly interacts with the lipid bilayer. In steady-state fluorescence experiments, changes of the ratio IE/IM and shifts of the transition temperature have been observed, reflecting changes of membrane structure caused by interaction with alpha-LA. Kinetic studies of the rate of interaction of alpha-lactalbumin and measurements of energy transfer from excited tryptophan(s) to the fluorescent probe confirm the steady-state experiments. Our results agree with previously reported microcalorimetric, gel chromatographic, and fluorescence polarization studies.
TL;DR: In this paper, the authors studied the lifetime and properties of fluorescence from polymers containing trans-1,2-dicarbazolylcyclobutane (DCZB) or carbazolyls structures in N,N-dimethylformamide.
TL;DR: In this article, the equilibrium internuclear geometry has been calculated for the excimer state of Xe2Cl and the absorption and emission transition probabilities for transitions that bear on the gain of the XeCl excimer transition and of the xeCl C-A transition.
Abstract: The equilibrium internuclear geometry has been calculated for the excimer state of Xe2Cl. At this geometry absorption and emission transition probabilities have been calculated for transitions that bear on the gain of the Xe2Cl excimer transition and of the XeCl C–A transition. The total lifetime of the Xe2Cl excimer state is found to be 330 ns for a fluorescence peak at 495 nm. Significant absorption is found to peak at 438 nm which would preclude tuning a laser over the entire fluorescence band. A very strong absorption from the Xe2Cl excimer state is also found at 339 nm which practically coincides with the broadband XeCl C–A transition.
TL;DR: The unique location of the excimer probe at tropomyosin Cys-190 and its characteristic long lifetimes could make it useful in time-resolved anisotropy studies and fluorescence energy-transfer experiments.
TL;DR: The results provide direct evidence for a lipid transition in the erythrocyte membrane and are similar to that reported for phospholipid bilayers and greatly exceeds that of protein conformation changes.
Patent•
07 Apr 1982TL;DR: In this paper, an excimer laser is described comprising a resonant optical cavity containing a gas-phase lasing molecular species, and means for coupling or applying microwave energy to the lasing species whereby the atoms or molecules of the molecular species are excited or pumped into their upper or energetic level from which they can emit photons.
Abstract: An excimer laser is described comprising a resonant optical cavity containing a gas-phase lasing molecular species, and means for coupling or applying microwave energy to the lasing species whereby the atoms or molecules of the lasing molecular species are excited or pumped into their upper or energetic level from which they can emit photons and make a transition to a lower unbound unexcited state.