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Benzylic amide [2] catenane (CAT1) deposited from a methanol solution onto highly oriented pyrolitic graphite (HOPG) has been investigated by ambient scanning tunneling microscopy (STM). Submolecular features are resolved which suggest that the adsorption of CAT1 is driven by the electrostatic attraction of carbonyl groups and HOPG. Our evidence shows that CAT1 is mobile at RT on HOPG surface. A statistical analysis of the observed features reveals a bimodal distribution of the lateral size which correlates with the expected diameter of a single macrocycle and the catenane respectively.

The in-situ electroluminescence and current voltage characteristics of organic light emitting diode deposited in UHV has been observed. Ultra High Vacuum (UHV) allows to study the system in a clean environment and to monitor in situ the effect of degradation associated with oxidizing agents when those are introduced in the chamber under controlled conditions. Furthermore the changes in the i-v characteristics upon oxygen exposure are reported proving the degradation even at low oxygen partial pressures (

The electroactive and photoactive properties of conjugated systems have attracted the interest of many laboratories, both for a basic understanding of their photophysics as well as for possible applications in organic-based optoelectronic devices, α-sexithienyl has been recognized as a model compound for a basic understanding of the electronic properties of conjugated materials. We report on ultrafast pump-probe measurements on ultra-high vacuum deposited thin films of α-sexithienyl, Femtosecond transient spectroscopy experiments were performed at low temperatures and over a wide wavelength range of the probe beam (from 420 nm up to 680 nm). The dynamics of the photoexcited species are discussed in the frame of the excitonic model.

The investigation of molecular vibrations is a powerful tool which can increase our knowledge on structures and on electron molecular vibrations, which are due to charge oscillation between dimerized molecules, coupled with totally symmetric intramolecular modes(1–3) Raman scattering studies account for totally symmetric vibrations. In addition, Raman spectroscopy can take advantage of resonant effects. In fact, when resonant conditions are fulfilled, selected molecular vibrations are obtained as well as information on the electronic manifold involved in the resonance process.

Nonlinear optical properties of a new thiophene based conjugated polymer (polythieno(3,2-b)thiophene, hereafter referred to as PTT) have been studied by two kinds of nonlinear spectroscopies: Photoinduced Absorption (PA) and Third Harmonic Generation (THG). PTT is a novel highly nonlinear optical material comparable to polythiophene, and can be prepared directly as an amorphous free standing film. The electronic nonlinear response measured by means of THG gives an average value of resonant χ(3) (-3ω,ω1,ω1,ω1) = 2×10-11 e.s.u. in the 1.25–1.45 µm range of the fundamental laser wavelength. The oscillations observed in χ(3) (-3ω,ω1,ω1,ω1) may be explained by three photon vibronic resonance enhancement with the C = C stretching mode. Photoexcitation of electron-hole pairs in the neutral polymer generates long-lived bipolaron states within the semiconducting gap. We relate the variation of the refractive index due to photoexcitations to the cubic susceptibility. In this framework χ(3) (-3ω,ω1,ω1,ω1) = 1.3×10-2 e.s.u. at the maximum of the low energy bipolaronic band.

We have designed and synthesized polydithieno[3, 4-b:3′,4′ −d]-thiophene (PDTT) which has good conductivity, low energy gap and a spectral window of transparency. The doped and undoped polymer exhibit an electrochromic effect in the visible spectrum range.

Efficient out-coupling light extraction and optical beam shaping have been combined to form an integrated, flexible illuminator that is based on organic light-emitting diodes (OLEDs). Spherical refractive microlenses were replicated by a cost-effective UV-casting technique onto a plastic foil to achieve the customized Gaussian distribution of the electroluminescence of an OLED pixel (50μm) matrix. The fabricated optical device, namely a ceiling light illuminator, shows an improvement of 70% in the out-coupled emission measured in the far field. The result corresponds to the theoretical prediction for isotropic emitting sources.

IR excited FT-Raman scattering measurements have been performed in YBa2Cu318O6+x with x = 0+0.2 . Because of the peculiar resonance condition with the electronic states induced in the system by the extra-oxygen a new, very strong band appears. A comparison of these results together with the FT-Raman spectra of single crystals at different oxygen concentration and selectively isotope substituted ceramics allows us to demonstrate that this band is associated with the Ag mode of the axial O4 atoms and describes the evolution of the electronic structure within the semiconducting gap with oxygen doping. The photoinduced absorption measurements (PA) performed on the same samples show that the features previously observed in 16O sample are genuine, and the isotope shift allows us to identify these bands as oxygen modes. A description of the electronic band structure around EF, and its evolution upon doping, consistent with the obtained experimental results, is proposed.

Iridium (2 µg) was deposited on a carbide-coated platform, pre-treated with about 1.2–1.3 µmol of Zr or W, and was evaluated as a permanent modifier in electrothermal atomic absorption spectrometry. The noble metal is not vaporized from the integrated platform of the transverse-heated graphite atomizer, provided that the atomization and clean-out temperatures do not exceed 2050–2100 and 2100–2200 °C, respectively. Under comparable conditions, Pd exhibits much worse thermal behaviour, being volatilized above 1300 and 1500 °C from Zr- and W-treated platforms, respectively. Pyrolysis–atomization curves were plotted for numerous hydride-forming and volatile analytes: Sb, As, Bi, Cd, Pb, Te, Tl, Sn and Se. The best characteristic masses for integrated absorbance measurements with the Ir–Zr-treated platforms are 92, 30, 176, 2.4, 35, 50, 65, 71 and 45 pg, respectively. Vaporization temperatures are generally above 1000 °C, except for Cd. The effect of atomization temperature on sensitivity in peak height and integrated absorbance measurements is discussed. Double peaks were observed for Bi and Te with Ir–W-treated platforms.

A sensitive method for the determination of Sb at ultratrace levels was developed by coupling continuous hydride generation with non-dispersive atomic fluorescence detection. A miniature argon–hydrogen diffusion flame was employed as the atomizer and a commercially available electrodeless discharge lamp as the light source. One of the main problems was the scattering signal generated by small droplets of solution which markedly deteriorated the signal-to-noise ratio. A simple way to remove the scattering signal was to operate under mild reaction conditions in order to minimize droplet formation. Under the optimized conditions, a limit of detection of 22 pg cm–3 of Sb (3s of the blank) was achieved, with a precision of 1.2% at the 5 ng cm–3 level and the calibration graphs were linear over more than 4 decades of concentration. L-Cysteine was employed both in the pre-reduction step and in the control of the interference effects arising from concomitant elements and acid mixtures. The analytical procedure was applied to the determination of Sb in certified reference materials of sediments, metallic copper and riverine water.

An attempt has been made to elucidate the mechanism of liquid-phase interferences caused by CuII, AgI and AuIII on the evolution of hydrogen selenide. An empirical equation able to describe accurately the interference plots obtained by systematic studies has been found. The equation has also been derived using a physical model for the interferences based on the capture of the hydrogen selenide by the active surface of metal colloid aggregates growing in the solution and having a fractal structure.

Conductive polyheterocyclic systems exhibiting different properties may be obtained by modifying the molecular architecture of the monomer units. Lowering the band gap value one can also achieve an intrinsically conducting polymer without the need of doping. Pursuing these objectives and on the basis of the experience on the fused thiophena-ring series, we have chosen the dithieno-[3,4-b:3′,4′-d]thiophene molecule as the building block for the following reasons: a) the large delocalization of π-electrons as compared to thiophene based monomers. b) the availability of specific and equivalent sites for the polymer propagation (α-positions with respect to the sulphur atom). The monomer undergoes to electropolymerization at low oxidation potential (1.04 V vs SCE), as described in ref. 1, the observed conductivity of as grown films is 1 Ω −1 cm −1 , while the band gap of the neutral polymer is 1.1 eV (0.9 eV lower than polythiophene). The intermolecular packing together with polymer enchainment is discussed in terms of X-ray diffraction analysis and molecular modelling calculations.

Pycnometric and dilatometric measurements have been made on solutions of K2SO4, K3Fe(CN)6, and K4Fe(CN)6 in water and in solutions 0.01442m, 0.03908m, 0.09044m of NaCl at 25°C. Deviations from the Debye—Huckel predictions even at very high dilutions are found for K2SO4 and K4Fe(CN)6. Some similarities are found with the predictions of the Mayer theory in the DHLL+B2 form, whereas the comparison is less favorable with the predictions of IPBE. As a general rule, when deviations from the Debye—Huckel theory are found in water solutions, the same kind of deviations are observed also in NaCl, even at very small concentrations of the multivalent electrolytes.

In the field of electroactive polyheterocycles we have experienced that modest modifications of the chemical architecture of the monomer may strongly affect the charge transport properties of the resulting electropolymerized material. Moreover the structural monomer variation influences the oxidation potential and the electronic properties of the polymer. With the aim of obtaining low energy gap polymers we envisaged two dithienobenzene structures as monomeric units with large π-electron delocalization. Both molecules undergo to electropolymerization and give semiconducting polymers, which electronic properties and structural aspects will be considered and discussed.

We present here a new low energy gap conducting polymer belonging to the family of the fused thiophene molecules: polydithieno[3,4b-3′,4′d]thiophene(poly-DTT′). Its optical properties have been extensively studied. The energy gap of this new polymer is of the order of 1.1 eV. The results derived from the electronic and vibrational spectra of the doped and undoped species are consistent with the bipolaron model. A strong electrochromic effect between a semitransparent (conducting) and an opaque (resistive) form has been observed.

The IR absorption properties of gettered annealed samples of YBa2Cu3O7−y have been shown to depend remarkably on the oxygen stoichiometry (0 < y < 1). A dramatic change of the spectral features is observed in the spectral region between 700 and 400 cm−1 at the phase transition for an oxygen composition between y = 0.7 and 0.8. The strong band at 591 cm−1 of the tetragonal phase, which vanishes completely after the occurrence of the phase transition, is attributed to k ≠ 0 transition induced by defects due to the random distribution of oxygen atoms situated between the barium planes. A new infrared phonon mode of 573 cm−1 appears at y = 0.38 and becomes rapidly the strongest band in the spectrum for y = 0.05 implying a strong electron-phonon coupling for this mode.

We investigate a series of sulfur-containing conjugated polymers, based on fused monomeric units of increasing size, in order to determine the relationship between the electronic and molecular structures, and the transport properties in this family of compounds. For this purpose, we compare the results of Valence Effective Hamiltonian calculations with experimental (infrared spectroscopy, X-ray diffraction, DC conductivity) measurements.

The apparent molar volumes of Mg, Ca, Sr, and Ba hexacyanocobaltates (III) have been determined from 1×104 to 0.2M (mol-dm−3), using both vibrating tube densimeter and dilatometric methods. The semiempirical Pitzer equation has been used to reproduce the experimental data. Positive deviations from the Debye-Hueckel limiting law (DHLL) have been observed at C

The infrared photoinduced absorption (PA) spectrum of the semiconducting tetragonal phase of YBa 2 Cu 3 O 7−y (y = 0.79 ÷ 0.85) is investigated in the 3200-400 cm −1 spectral range and a direct evidence of the electron-phonon coupling with the Cu-O totally symmetric modes is presented. The observation of the PA bands at 435 and 510 cm −1 shows that both the symmetric bending vibration of the Cu-O planes and the symmetric Cu-O axial stretching vibration are involved in the coupling. The lack of a PA effect in the 3000 cm −1 (0.37eV) spectral range suggests the absence of an excitonic band at midgap.

The infrared photoinduced absorption (PA) spectrum of the semiconducting tetragonal phase of YBa 2 Cu 3 O 7−y ( y = 0.79 ÷ 0.85) is investigated in the 3200–350 cm −1 spectral range at low temperature (34 k). A broad electronic band is observed at 0.13 eV and is attributed to long lived metastable hole states generated by photoexcitation. Two PA phonon bands observed at 435 and 510 cm −1 correspond to totally symmetric modes of 1-2-3 involving Cu-O vibrations parallel to c axes. A vibronic activation mechanism is proposed in order to account for their IR activity and the nature of the .13eV midgap hole state is discussed in this framework.

A new conductive polymer is prepared by electropolymerization of thieno(3,2-b)thiophene. Electrochemical characterization by cyclic voltammetry shows that it can be repeatedly driven between the doped and the undoped species. The FT-IR spectra of both materials are compared and the electrical conductivity is shown to be 3 × 10 −6 S cm −1 .

The infrared photoinduced absorption (PA) spectrum of the semiconducting tetragonal phase of YBa 2 Cu 3 O 7−y (y = 0.79÷0.85) is investigated in the 3200-350 cm − spectral range at low temperature. A broad electronic PA is observed at 0.13 eV and is attributed to a deep midgap hole state generated by photoexcitation of e-h pairs. Two PA phonon bands observed at 435 and 510 cm −1 correspond to totally symmetric vibrations of YBa 2 Cu 3 O 7−y involving the CuO bonds perpendicular to the CuO planes. A vibronic activation mechanism is proposed in order to account for their IR activity and the mature of the .13eV midgap hole state is discussed in this framework.

Infrared excited Raman spectra at 1064 nm (1.16 eV) of the YBa2Cu3O7-y superconducting ceramic system were measured by means of Fourier transform interferometry (FT-Raman) at different oxygen stoichiometries. The standard Raman scattering spectrum excited with visible light was measured for comparison. The FT-Raman spectrum of YBa2Cu3O7-y (y≥0.7) is dominated by the multiple order scattering of the 505 cm-1 Ag Cu(1)-O(4) axial stretching vibration. This effect is accounted for by a Frank-Condon Raman scattering due to the strong electron-phonon coupling between the axial mode and the local electronic transitions that contribute to the low energy absorption tail of YBa2Cu3O7-y. In view of this we tentatively assign the interband gap to a perpendicular charge transfer transition.

An exhaustive characterization of an homologous series of polycondensed thiophene based polymers has been carried out in order to provide a comparative and consistent survey of some of the crucial properties that are generally related to the electrical properties of poly-heterocycles.

The infrared absorption spectrum of polycrystalline samples of YBa 2 Cu 3 O 7 is reported in the temperature range of 300-30K Four phonon modes are observed at 436, 488, 579 and 622 cm -1 which have not been observed yet by reflectance spectroscopy indicating that the microscopic properties of the surface are different from the bulk. A comparison between our infrared data and the Raman scattering data in the literature suggests that two “gerade” modes at 436 and 579 cm -1 are strongly coupled with the underlying electronic transition, becoming infrared active.

IR absorption spectra of polycrystalline pressed samples of the organic metals α-(BEDT-TTF)2I3, β-BEDT-TTF)2I3 and (BEDT-TTF)2Cu(NCS)2 are presented and discussed. Normal protonated as well as deuterated materials were studied. The spectra range from 400 cm-1 to 5000 cm-1 and are similar to the IR reflectance spectra reported ealier. The data are of special interest in view of the fact that recently bulk superconductivity was observed in such polycrystalline samples of organic metals, and therefore the application of organic superconductors for the preparation of electronic devices seems possible.

The enhancement of the third order nonlinear susceptibility χ(3)) of an homologous series of polycondensed thiophene based polymers was observed about photoinduced polaronic bands by a novel “pump-probe” degenerate four wave mixing echnique. Enhancement of the degenerate four wave mixing signal for more than an order of magnitude was achieved with response time of less than 25 ps. The intrachain polarons contribution is proposed as the possible mechanism responsible for the observed enhancement.

Nonlinear optical properties of two thiophene-based conjugated polymers (PTT and PDTB) were studied by the photoinduced absorption spectroscopy and the third harmonic generation spectroscopy. The results obtained with these two methods are used to estimate the value of χ(3) in these materials. Resonant χ(3) are (2.0 ± 0.2) × 10−11 e.s.u. and (1.0 ± 0.1) × 10−11 e.s.u. for PTT and PDTB, respectively. χ(3) is shown to be related to the width of the optical gap through a sixth-power law. In PTT a vibronic structure due to the C = C stretching mode appears in the χ(3) spectrum.

The IR and near-IR photoinduced absorption (PA) spectra of the semiconducting tetragonal phase of YBa2Cu3O7−y (y = 0.79÷0.85) are investigated in the 0.045−2 eV spectral range at low temperature. Two electronic PA bands are observed at 0.13 and 1 eV and are attributed to midgap states generated or populated by photoexcitation of e-h pairs. Several hypothesis on the origin of these bands are proposed. PA phonon bands observed at 435 and 510 cm−1 correspond to totally symmetric vibrations of YBa2Cu3O7−y involving the Cu-O bonds perpendicular to the Cu-O planes. A vibronic activation mechanism is proposed in order to account for their IR activity and the polarization of the .13 eV midgap state is discussed in this framework.

The mechanism of hydride atomization and the fate of free atoms was investigated in the miniature diffusion flame. Selenium hydride was used as a model for the other hydrides. Mercury vapor was employed as an analyte to study physical processes, such as macroscopic movements and free atom diffusion, controlling the distribution of free analyte atoms in the observation volume, separately from chemical reactions of the free atoms. Free atoms were detected by atomic absorption spectrometry. Spectroscopic temperature measurements based on atomic absorption at 196.1 and 204.0 nm Se lines were used to determine the temperature distribution. The spatial temperature distribution was highly inhomogeneous ranging from 150°C to 1300°C. The whole flame volume is actually a cloud of hydrogen radicals maintaining analyte in the free atom state since hydrogen radicals formed in outer zone of the flame diffuse to its cooler inner parts.

Photoluminescence and photoconductivity action spectra of α-sexithienyl (T 6 ) are reported and discussed. The photoluminescence spectrum of oriented sublimed thin film of T 6 at 4.2 K shows a one to one correspondence with similar spectra of good crystalline quality of chemically synthesized polythiophene (PT). The photoconductivity action spectrum of T 6 is complementary to the luminescence excitation spectrum indicating that the electron-hole pair creation is the dominant channel of non radiative decay for excitation higher than the bottom of the lowest B u excitonic band. We suggest T 6 as a good model compound for PT.

We discuss the sensing properties of C 60 thin films towards reducing gases and humidity. C 60 thin films were sublimed onto alumina substrates with platinum interdigitated contacts, and a platinum heating element was deposited on the substrate back face. The electrical responses of the C 60 films towards 1000 ppm of hydrogen, ethyl alcohol and carbon monoxide were measured both in dry and humid air, in the temperature range between 50 and 300 °C. At 300 °C we observe a reversible increase of the current in the presence of hydrogen, while the water vapour causes a reversible decrease in the current. We suggest that the response to hydrogen may be due to a chemical reaction between the oxygen molecules trapped in the film and the hydrogen, reducing the concentration of oxygen-based electron traps in the C 60 , hence increasing the conductivity. The reduction in conductivity in the presence of humidity is probably due to the formation of extra trap states by water molecules in the film.

The crystal structure, the optical spectra and electrical conductivity of dithieno(3,2-b; 2′,3′-d)thiophene-tetracyanoquinodimethane (DTT-TCNQ) charge-transfer complex have been measured. DTT-TCNQ crystallizes in the monoclinic space group P21/c with a = 7.206(2), b = 7.574(2), c = 32.324(9), β - 92.18(4)°, Z - 4, and the donor and acceptor molecules are arranged in alternated stacks. The low conductivity (a = 10−2 S cm−1 for the single crystal, along the stacking axis a) is characteristic of a semiconductor with activation energy of .61-.76 eV, and is related to the alternate stack structure. Despite the poor condctivity of the DTT-TCNQ CT complex we estimated, from structure and IR data, a low degree of ionicity (p = .2–.3) which characterizes the DTT molecule as an interestign donor. The polarized IR spectra shows the effect of vibronic activation of some of the ag modes of TCNQ.

We report measurements on steady state and time resolved photoluminescence (PL) and PL-excitation (PLE) of sexithiophene single crystals and evaporated thin films. In contrast to the broad spectral features usually observed even in crystals, we have observed for the first time sharp emission peaks from the single crystal superimposed on a broader background. The broad background is due to emission from defect states, which are observable in PLE measurements and site-selective PL. These defect states are visible both in films and crystals, but their density and nature are strongly dependent on the growth conditions. Additionally in the film a fast energy transfer from the primary excited molecular states to defect states is observed on a sub 100 ps timescale whereas the fluorescence lifetime of these defects is around 700 ps.

Inelastic neutron scattering experiments are combined with infrared and Raman data to obtain a uniquely defined description of the intramolecular vibrations of three oligomers of polythiophene. Through refinement of ab initio force fields, the three vibrational spectra of each oligomer are simulated with remarkable accuracy. Two different basis sets of atomic orbitals are used: the first, is 6‐31G* and is used to optimize the geometries and calculate the relevant force fields of α‐2T and α‐4T, the second is 3‐21G* and is used for the same purpose for α‐4T and α‐6T. To improve agreement with the experiment, the force fields are scaled. In this way, one set of scaling parameters is generated for the 6‐31G* basis and another for the 3‐21G* basis. The parameters are common to both molecules calculated with either basis sets and are believed to be transferable to higher isomers. The fitting procedure is applied in steps: first, the calculated vibrational frequencies are assigned on the basis of the experimental infrared and Raman activity, then a fitting of the Inelastic Neutron Scattering profile is performed, finally, the infrared and Raman spectra are calculated with the new normal modes and the ab initio derivatives of the dipole moment and the polarizability. The procedure is iterated until the three spectra of each oligomer are satisfactorily reproduced. For α‐4T, two scaled force fields are obtained—one for each basis set—and are shown to yield very similar normal modes. It is important to emphasize that not only the vibrational frequencies but also the spectral intensities are well reproduced by the simulations. Implicitly, this means that the dipole moment and the polarization tensor surfaces calculated ab initio at the potential energy surface minimum are of good quality. The procedure is absolutely general and can be applied to any molecular system. In the present case, it leads to well defined force fields that give us a stringent picture of the vibrations of these molecules.

A review of our investigations of Raman spectra of intramolecular and external modes in pristine and doped fullerene C 60 is given. Experimental results are compared with group-theoretical predictions. In low-frequency spectra of M 6 C 60 new bands are found that we have assigned to external modes. An interpretation of M 6 C 60 external modes and lattice dynamics calculations are carried out. From an analysis of the excitation profile of resonant Raman spectra it is found that expected changes of internuclear distances in the excited state of C 60 should be close to the form of the A g mode at 1468 cm −1 . Moreover, a destructive interference of A g modes in M 3 C 60 and M 6 C 60 is observed. The essential broadening, a shift and the Fano lineshape of low-frequency intramolecular H g bands in metallic M 3 C 60 are found. A narrowing of these bands in insulating C 60 and M 6 C 60 indicates the strong electron-phonon interaction of H g Jahn-Teller modes. An estimation of the electron-phonon coupling constants for some modes is given. A possible origin of low-energy electronic excitations appearing in M 3 C 60 resonant Raman spectra at λ i = 1064 nm excitation is discussed.

The in situ collection of volatile hydrides in an electrothermal atomizer with an integrated platform pre-treated with 110 µg of Zr or 240 µg of W and 2 µg of Ir for permanent modification was studied. An optimization study of the performance characteristics of an automated FI-HG–ETAAS system based on an FI hydride generator interfaced with a transverse-heated graphite atomizer and longitudinal Zeeman-effect background correction was elaborated. The HG step for AsIII, AsV, BiIII, SbIII, SbV, SeIV, SnIV and TeIV, as well as for several alkylated species of As and Sn, was optimized by means of a full factorial 32 design, the factors being the concentrations of acid and tetrahydroborate (or their supply rates in µmol s–1).The corresponding regression equations are tabulated, and representative response surfaces and contour diagrams are plotted. All inorganic hydrides except for SnH4, are generated and collected with high efficiency at tetrahydroborate concentrations of 0.25–0.4% m/v, sample acidity of 1.5–3 mol l–1 HCl, trapping temperatures of 400 °C and a purge gas flow of argon of 100–130 ml min–1. The optimum conditions for stannane and alkyltin hydrides are: pH 1–4, tetrahydroborate concentrations of 0.2–0.4% m/v, trapping temperatures between 400 and 600 °C and argon flow rates of 60–120 ml min–1. Arsine, monomethylarsine and dimethylarsine are effectively collected on both coatings at temperatures between 400 and 500 °C and purge gas flow rates of 70–120 ml min–1. Optimum HG conditions differ strongly for AsIII, AsV, monomethylarsonate and dimethylarsinate species with this FI system, unless L-cysteine is added. Organoelement species of As, Sn and Se are thermally stabilized in a similar manner on both Ir–Zr- and Ir–W- treated platforms, the least stable species being selenornethionine and trimethylselenonium. The best levelling-off effect on the integrated absorbance for different analyte species (isoformation) is observed for As and the worst for organotins, particularly for trialkylated species such as tributyltin, trimethyltin and trimethylselenonium. Relatively better isoformation is achieved for organotins on Ir–W- and for organoselenium on Ir–Zr-treated platforms. The long-term stability of the Ir–Zr and Ir–W modifier coatings during at least 600–700 thermal cycles is demonstrated. The Ir–Zr treatment is preferred to Ir–W for hydride trapping, owing to lower atomization temperatures, longer lifetime of the atomizer and an absence of double peaks. Such peaks persist for Bi and Te on Ir–W-treated platforms. The best characteristic masses in integrated absorbance measurements with Ir–Zr-treated platforms are close to those for the direct injection mode, viz., 35, 107, 83, 43, 104, 48, 31, 32, 153, 146, 148, 145 and 152 pg for ASIII, BiIII, SbIII, SeIV, SnIV, TeIV, monomethylarsonate, dimethylarsinate, monomethyltin, dimethyltin, trimethyltin, diethyltin and monobutyltin, respectively. Analytical results for As, Sb and Se in certified reference materials (water and autoclave-decomposed sediments) are in good agreement with the certified contents.

We have investigated the chemical nature and the electronic structure of the interface between a low work function metal, aluminum, and a conjugated polymer semiconductor, polythiophene. We have studied the initial stages of the interface formation by depositing the metal onto the surface of a polymer film. Charge transfer processes between the metal and the polymer are analyzed using core‐level x‐ray photoelectron spectroscopy (XPS); the evolution upon metallization of the valence electronic levels directly related to the polymer electronic structure is followed with ultraviolet photoelectron spectroscopy (UPS). With these techniques, we investigate the deposition of aluminum on two polythiophene systems (i) the alkyl‐substituted poly‐3‐octylthiophene and (ii) the α‐sexithiophene oligomer. The experimental data are compared to the results of a recent quantum chemical study on model systems consisting of thiophene oligomers (up to sexithiophene) interacting with a few Al atoms. The interaction of polythio...

Luminescence of singlet oxygen at 1287 nm in the C60 solid film with longwave and continuous excitation (514.5, 670 and 1064 nm) is studied. The twofold increase of the siglet-oxygen luminescence intensity with excitation at 670 nm in comparison with one at 514.5 nm is observed. A band of photo-luminescence in C60 at 13300 cm−1 is observed. It is found that the quantum yield of this luminescence decreases when the excitation wavelength changes from λi = 514.5 nm to λi = 647.1 nm. From an analysis of the photoluminescence intensity at evacuating air we have concluded that oxygen molecules are trapped in a surface layer of the C60 solid film.

We have investigated the disorder-determined optical properties of α-sexithiophene by comparing measurements of an evaporated film and a single crystal. We observed for the first time sharp lines in absorption and photoluminescence from both samples representing the intrinsic electronic properties of the material. The time-integrated emission spectra of both samples are dominated by radiative trap emission, which is more pronounced in the film due to the higher degree of disorder. Photoluminescence excitation and site-selective photoluminescence measurements show the different origin and character of the traps in the samples. We attribute the single crystal traps to the so-called X-traps while the nature of the traps in the film is still undetermined. Time-resolved photoluminescence measurements of the film show a fast transfer process of the sharp bulk emitters to the unstructured trap emission within the first 50 ps after excitation. A comparable process is observable in the single crystal, showing a slower dynamics due to lower trap density.

α-sexithienyl (T6) is a large oligomer of polythiophene with twelve conjugated double bonds forming highly ordered thin films. The chemical definition and the ordered solid state aggregation allows to investigate the energetics of the molecule as a model for polythiophene. Linear spectroscopy including single crystal and ordered thin film absorptiion and one-photon excitation allows to locate and to assign the lowest Frenkel 11Bu exciton at 17450 cm−1. Nonlinear two-photon absorption spectroscopy on the film allows to locate the lowest 21AAg Frenkel exciton at about 900 cm−1 above the 11Bu e-e correlation is therefore crucial in determining the energetics of T6. The level crossing of the 11Bu and 21Ag states provides an efficient radiationlless relaxation pathway. We suggest that the energitics of T6 provides a good model for the understanding of polythiophene.