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We report the ability to spectrally resolve excited-state ensembles of pyranine (Py) utilizing nanometerthick metal films as a low-cost analytical tool. Surface plasmon coupling allows to mitigate the effect of spectral broadening that is responsible for blurring the emission spectrum at room temperature, a situation common in conventional fluorescence spectroscopy. The approach is especially useful in the case when several excited-state species are present. Fluorescence emission from closely located protonated, deprotonated, and excimer species of Py couple into surface plasmons and are easily separated and observed with 11-14 fold intensity enhancements. Furthermore, the ultranarrowband photon-sorting of emission from microenvironments in a multispecies system is performed in this study using instruments that are readily available in most laboratories without employing any deconvolution procedure and/or additional dispersive optics. OCIS codes: 240.0310, 300.2350, 300.6320, 310.6188.

Transient infrared (IR) absorption spectroscopy is used for examining the solvent reorientation process of intramolecular charge transfer (ICT) process of (p-cyanophenyl)-pentamethyldisilane (CPDS)-[[[H.sub.2]O].sub.2] cluster in the excited-state. Findings reveal that water molecules are hydrogen-bonded with each other in the charge-transfer (CT) state.

The simple alkyl linked systems are investigated for their propensity toward intramolecular exciplex formation and the subsequent charge-transfer interaction of their excited states. The magnitude of the electronic coupling between donor and acceptor is found to be strongly influenced by increasing the length of the alkyl chain linker.

Absorption, emission, and excitation spectra for solid-state and solution of Tb(III), Dy(III), and Gd(III) complexes with the polypyridine ligand 6,6'bis[bis(2-pyridylmethyl)-aminomethyl]-2,2'-bipyridine (C36H34N8) are presented. A report on the measurements of excited-state lifetimes and quantum yields in various solvents at room temperature and 77 K is presented and used to characterize the excited-state energetic of this system.

The potential energy profiles for proton-transfer of 2-hydroxypyridine and its complexes with water were determined by MP2, CASSCF and MR-CI calculations with the 6-31G** basis set. The results predict that the photoinduced tautomerization reaction between the enol and keto forms involves a cyclic transition state having one or two water molecules as a bridge.

A report that generation of the naphthylmethyl radical, produced through the naphthymethyl-oxygen (C-O) bond cleavage, can be controlled by two- or three-laser irradiations through the higher triplet excited states (Tn) is presented. The results revealed that acenaphthene was produced as the final product during the stepwise C-O bond cleavage of 1,8-(BPOCH2)2Np and 1,8-(PhOCH2)2Np.

Time-correlated single photon counting (TCSPC), multiplex transient grating (TG), and fluorescence upconversion (FU) measurements is performed to characterize the quenching mechanism. The emission of the ligands is dramatically altered, with a significant increase in the quantum yields due to coordination-induced deactivation of the macrocyclic amine lone pair electron donors.

A study is carried out on the metal (4f)-ligand (Cl 3p) bonding in LnCl(sub 6)(super 3-) (Ln = Ce to Yb) complexes on the basis of 4f--->4f and Cl,3p--->4f charge-transfer spectra. The results show that eliminating artificial ligand-to-metal charge transfer in Kohn-Sham calculations by a procedure described in this study leads to energies of 4f--4f transitions.

A study prepares and characterizes a series of axially ligated complexes of iron(III) octaalkyltetraphenylporphrins by (super 1)H NMR spectroscopy. The results show that the temperature dependences of the proton resonances of the complexes show significant deviation from simple Curie behavior.

The effect of interchain interaction on the triplet excited state in two Pt-acetylide polymers of the type [-trans-Pt(PBu3)2--C(triple bond)C--Ar--C(triple bond)C--](sub n), is explored where Ar is either 1,4-phenylene or is based on the pentiptycene unit. Weak phosphorescence emission from an interchain aggregate is observed from parent polymer both in solution and in the solid state as indicated by the spectroscopic studies.

A way of controlling the formation of the two types of zexanthin aggregates in hydrated ethanol, such as J-zeaxanthin and H-zexanthin is presented. Time-resolved experiments revealed that excitation of the 530-nm band of J-zeaxanthin produces a different relaxation pattern than excitation at 485 and 400nm showing that the 530-nm band is not a vibrational band of the S(sub 2) but a separate excited state formed by J-type aggregation.

The excited singlet states of tirapazamine (TPZ), desoxytirapazamine and its isomer dTPZ', quinoxaline di-N-oxide (QXNO), and phenazine di-N-oxides (PNNO) were studied. The laser flash photolysis of tirapazamine (TPZ) and desoxytirapazamine (dTPZ) produces their excited singlet states and the S(sub 1) states were observed by picosecond time-resolved absorption spectroscopy.

A novel approach to achieve NC lasing in the Auger-recombination-free regime by using type II NC heterostructures that promote spatial separation on electrons and holes is explored. It is presented that such hetero-NCs can exhibit strong repulsive excition-excition interactions that lead significantly reduced excited-state absorption associated with NCs containing single electron-hole pairs.

The steady state and time resolved phophysical properties of a novel self-assembling lyotropic discotic liquid crystal, 2,3,6,7,10,11-hexa-(1,4,7-trioxaoctyl)-triphenylene (TP^EO2M) are reported. Findings indicate that this lyotropic system has an order of magnitude higher concentration of intrinsic traps in the isotropic phase than its thermotropic analogues display in the columnar mesophase.

The upcoversion luminescence of bulk and nanocrystalline Lu1.98Er0.002O3 following excitation into the (super 4)I(sub 11/2) level suing 980 nm radiation are investigated. The upconverted luminescence intensity for the nanocrystalline sample was lower than its bulk counterpart owing to higher probability of multiphonon relaxation because of the adsorbed CO2 and H2O on its surface.

CO adsorbed layer of Pt(111) electrode undergoes reconstruction when exposed to UV-irradiation (266 nm) from a nanosecond or femtosecond laser. UV induce CO desorption and retrapping cycles, which passed through electronic excited states at the surface were sustained on the electrode surface.

The excited-state dynamics of 'nonfluorescent' flavoproteins are examined, and thus fluorescence quenching mechanisms of these flavoproteins are interpreted as due to the ultrafast electron transfer (ET) to flavin chromophore (F) in the excited electronic state from nearby tryptophan (Trp.NH) or tyrosine (Tyr.OH) residues placed in the protein nanospace (PNS), on the basis of their X-ray structures.

Research is presented describing the use of crossed beams to produce an excited nitrogen acetylene compound forming cyanomethylene.

The article discusses the use of photophysical studies to observe the chemical 1,2-C(sub 70)J(sub 2).

An unusual band shape is exhibited in the absorption spectra of Ni(H(sub2)0)(sub6)(super2+), trans-NiC1(sub2)(H(sub2)0)(sub4) and NiC1(sub6)(super4-). A broad band an intense vibronic progression, having a spacing larger than totally symmetric ground-state metal-ligand vibrational frequency are superposed. Both the large interval and the band intensities were found to occur from efficient intersystem crossings between the two excited states.

The ground state sigma interaction between Fe-Fe in the mixed valence dimer, (Fe2(OH)3(tmtacn)2)2+ forms an orbit-pathway for valence delocalization. Vibronic analysis relates this pathway with the electronic-coupling matrix element, H(sub AB). The analysis of near-IR sigma-sigma* resonance, Raman spectra, and variable temperature absorption bands in the class-III delocalized mixed valence dimer, explain the geometric distortions along with the excitation. Relationship between totally-symmetric nuclear coordinates in absorption and the Q-vibrational coordinate is also discussed.

The compound (Ir(bpy)x(phen)(sub 3-x))(super 3+) has values equalling 1 and 2 for x. Both substitutions reveal processes in presumed 'dual emission' properties. State energies, which are luminescent and ligand-centered, spread on their own accord to determine the emission. A reversal in the sequence of the states reveal the repeated presence of separate complex ions in solutions. Phonon-assisted energy back transfer takes place from low limits of energy ligand to higher limits due to increase in temperature. Lorentzian widening of resonantly-thinned luminescence may be employed to study the rate of transfer.

It was proved that ReL(Co)3CNR+ complexes possess useful characteristics such as high quantum yields and long fluid solution lifetimes. The complexes can also be modified to be extended to the design of systems with specific binding properties which can be employed in molecular probes. The ability to modify their structuring by small variations makes them useful systems for analyzing excited-state dynamics and equilibrium in the low-lying photophysically and photochemically vital excited states of metal complexes.

A strategy was outlined that enables engineering of conjugated oligomeric structures that possess highly delocalized singlet (S1) excited states yet manifest apparent E(sub 1/2)(super 0/+) and E (sub 1/2)(super -/0) values that are essentially invarient with respect to those elucidated for their constituent monomeric precursors. The magnitudes of the potentiometric HOMO-LUMO gap (Ep) and optical band gap (E(sub op) in conjugated organic materials can be modulated independently.

The nonlinear optical properties of a new chromophore erbium two-photon dye salt are studied in THF solution. The theoretical analysis shows a 3 order of magnitude increase in the intersystem crossing rate due to the presence of erbium.

Narrow band yttrium iron garnet-gadolinium gallium garnet waveguides 1.14- and 0. 49-nanometers wide are optically probed to yield the transverse width surface modes of magnetostatic waves (MSW). The diffraction peaks of different transverse magnetostatic modes are detected by the resolution of the optical technique, which uses four first-couples of the optical waveguide modes. The efficiency of excitation of transverse MSW modes in a narrow channel waveguide are measured directly by this method.

Femtosecond fluorescence up-conversion technique is used for examining the photoinduced excitation energy transport dynamics in oligothiophene-fullerene linked dyads. Findings reveal a remarkable difference of sub-picosecond dynamics between the blue wing and the red wing of the nT fluorescence band in longer oligothiophenes of reference compounds without the C60 moiety.

Several cyanosilylenes, XSiCN (X=H, F, Cl, CH3, SiH3, CN) are found to have singlet states with rather high electron-affinities. Bound excited negative ion states exist within these silylenes, and these anion states, which belong to the totally symmetric irreducible representations, and characterized as dipole-bound negative ion states, have larger dipole moments than the singlet states.

Synthesis of semiconductor device design requires access to realistic physical models and adaptive algorithms. The elements of a quantum-confined Stark-effect modulator were designed for such synthesis and optimization with respect to a target function was achieved using a genetic algorithm.

An unusually large positive solvatochromic shift in excited-state intramolecular proton transfer (ESIPT) keto fluorescence originating from the creation of an intramolecular charge-transfer (ICT) state after the ESIPT process is reported. The introduction of a conjugative electron acceptor in HBO causes a strong positive solvatochromism in ESIPT keto emission.

An ultraviolet (UV)-infrared (IR) double resonance spectroscopy with related fluorescence detection is applied to the observation to the IR spectrum of aniline in the first electronically excited (S(sub 1)) state. On examining the IR spectra for several deuterium substituted species, it is found that NH2 stretching vibrations of the S(sub 1) state are located at 3000 cm(super -1), representing extremely large frequency decrease upon electronic excitation.

A new optical sensor suitable for practical measurement of extracellular potassium is described. The potassium fluoroionophore sensor is found to respond rapidly and reversibly to changes in potassium concentrations typical of whole blood samples.

Data which showed that a symmetric cofacial 5PDI dimer undergoes symmetry breaking following photoexcitation yielding complete charge seperation between the two halves of the dimer in the relatively low polarity solvent toluene was presented. The results suggested that excited state symmetry breaking in 5PDI dimers provides new routes to biomimetic charge separation and storage assemblies that were more easily prepared and modified than those based on multiple tetrapyrole macrocycles.

The mechanism of bioluminescence color determination is studied. This study supports MaCapra's mechanism of firefly bioluminescence color.

A method for highly selective excitation is proposed where coherences are transferred between individual transitions. This method is capable of exciting signals selectively despite severe overlaps.

The deposition of large amounts of vibrational energy in the gas-phase SN2 reaction is shown to result in a nonstatistical rise in observed efficiency. An intermediate A was generated from the carbonyl displacement reaction of CH(sub3)O- + CF(sub3)COC1. The nonstatistical behaviour is thought to be due to the fast SN2 reaction relative to the rate of energy redistribution. Studies of reactive intermediates with subnanosecond lifetimes will continue to provide insights into the dynamics of SN2.

Experiments were undertaken to test whether excited-state intramolecular proton transfer (ESIPT) reactions can operate for m- and -hydroxy-substituted styryl systems 1-3, where acid/based moieties are distal from each other. Each reacted efficiently in aqueous solution, giving a corresponding photohydration product. This shows the involvement of proton transfer, needing a proton relay mechanism, helped by solvent water.

The article discusses research methods used to study the positioning of intramolecular hydrogen bonds when seeking to obtain an excited state intramolecular proton transfer.