Susumu Matsuzaki

Raman spectra of conducting TCNQ salts; Estimation of the degree of charge transfer from vibrational frequencies

Abstract The linear dependency of TCNQ ν4 frequencies on the formal charge was observed and was attributed to the motional narrowing of the Raman band by hopping of conduction electrons. The formal charges of TTF-TCNQ (0.59) and NMP-TCNQ (0.62) estimated from this dependency agreed well with those from other experiments.

Raman spectra of mixed valent TTF salts; relation between Raman frequency and formal charge

Abstract Raman spectra of mixed valent TTF halides and TTF-TCNQ were obtained. A plot of the TTF frequencies vs. the formal charge (ϱ) gives straight lines and ϱ of TTF-TCNQ estimated from the Raman frequencies agrees well with those from other experiments.

Conformational changes of poly(3-alkylthiophene)s with temperature and pressure

Abstract Thermochromism of cast films of poly(3-hexylthiophene) and poly(3-dodecylthiophene) was studied by electronic absorption and FT-IR spectra. A possible mechanism for the transition is discussed from the viewpoint of conformational changes of the methylene side chains deduced from the FT-IR spectra. Electronic absorption and vibrational spectra of poly(3-hexylthiophene) films were measured at high pressures by use of a diamond anvil cell. The absorption edge energy decreased with increasing pressure up to 3 GPa and then showed leveling off and subsequent increase. The decrease is probably due to an increased conjugation length of the thiophene main chain caused by a compact packing of methylene side chains. On the other hand, the increase in the edge energy is attributed to a distortion of a plane polymer structure caused by the steric hindrance between neighboring polymer chains. Electric conductivity of a poly(3-hexylthiophene) film showed the pressure dependence parallel to that of the absorption edge.

Electronic structure of lithium phthalocyanine studied by ultraviolet photoemission spectroscopy

Abstract The electronic structure of the stable organic radical compound, lithium phthalocyanine (LiPc), was investigated using ultraviolet photoemission spectroscopy (UPS). The observed UPS spectra were compared with those of metal free phthalocyanine (H 2 Pc) and zinc phthalocyanine (ZnPc). The spectral features of LiPc and ZnPc were analyzed with the aid of ab initio MO (molecular orbital) and density functional theory (DFT) methods. These three compounds showed similar spectral features, and the binding energy of each spectral structure had almost the same value. In addition to this, the ionization threshold of LiPc in the solid state was found to be nearly equal to those of the other compounds: the values are 4.9 5 eV for LiPc, 5.1 2 eV for H 2 Pc, and 5.0 3 eV for ZnPc. These observations show that these phthalocyanines have similar electronic structures in the top region of the valence band and that the radical electron exists in the molecular orbital of the phthalocyanine ring, which is the highest occupied molecular orbital (HOMO) of H 2 Pc and ZnPc. In contrast to this, the work function of LiPc was about 0.2 eV higher than those of other compounds, and its value was found to be 4.4 3 eV. This means that the unoccupied states of LiPc should differ from the closed shell compounds such as H 2 Pc and ZnPc.

Anomalous shock compression behavior of yttria‐doped tetragonal zirconia

Shock‐wave measurement and shock‐compression recovery experiments of yttria (Y2O3) ‐doped (3.0 mol %) tetragonal zirconia in the pressure range up to 125 GPa were performed to study the anomalous shock compression and release behaviors. The minute three‐wave structure with the transition points of 15–17 and 33–35 GPa was observed also by the inclined‐mirror method, which is consistent with the VISAR (velocity interferometer system for any reflector) data. The shock velocities of the second wave were so fast that the first transition could not be identified as a normal elastoplastic transition. The shock velocity Us versus particle velocity Up relation of the final wave was given by Us=2.71+2.39Up km/s. The equation of state of the final phase was analyzed by using a program based on the Debye model, the Mie–Gruneisen equation, and the Birch–Marnaghan equation. The volume change between the tetragonal phase and the final phase at zero pressure was estimated to be 18%, which was larger than that expected fo...

Polymerization of benzene occluded in graphite-alkali metal intercalation compounds

Abstract Benzene accommodated within the interlayer space of graphite-alkali metal (potassium and rubidium) intercalation compounds was found to be polymerized not only to biphenyl, but also to terphenyl and quaterphenyl, while only biphenyl was formed by the action of potassium or rubidium metal alone under the same conditions. The formation of higher oligomers of benzene in the interlayer space of graphite intercalation compounds is to be ascribed to the amphoteric nature of the compounds, which are capable of both donating and accepting electrons.

Electrical conductivity of a Cs2(TCNQ)3 single crystal measured at high pressures by a diamond anvil cell

Abstract An improved method by a diamond anvil cell was developed to measure electrical conductivity of a single crystal up to 10 GPa. The resistivity of a single crystal of Cs2(TCNQ)3 at 6 GPa was about 10−4 smaller than the value at ambient pressure. The pressure dependence of resistivity revealed phase transitions at about 2 and 6 GPa. Large hysteresis caused by the phase transitions was observed in a compression-decompression cycle at high pressures.

Pressure-induced neutral-ionic transition in a 2:1 charge transfer crystal of tetrathiafulvalene and iodanil, (TTF)2IA

Abstract Pressure dependence of a C=O stretching IR frequency of iodanil has revealed a neutral-ionic transition at 3.1 GPa in a 2:1 charge transfer crystal of tetrathia-fulvalene (TTF) and iodanil (IA), (TTF) 2 2 IA, which is composed of TTF-IA-TTFsandwichtrimers. Two IR bands corresponding to a quasi-neutral and a quasi-ionic TTF species were simultaneously observed above the transition pressure.

Partial charge transfer in HMTTeF-TCNQF4

Abstract The degree of charge transfer in a solid complex of tetrafluorotetracyano- p -quinodimethane (TCNQF 4 ) with hexamethylenetetratellurafulvalene (HMTTeF) was estimated at ≈ 0.75 by Raman spectroscopy. X-ray photoelectron spectra of N 1s electrons also demonstrate the mixed-valency state of the complex, which can explain its high electrical conductivity.

Benzene in graphite-potassium intercalation compounds studied by resonance raman spectroscopy

Abstract Benzene occluded in the interlayer gaps of graphite-potassium intercalation compounds KC 24 and KC 8 , was found to be dimerized to biphenyl (Bp) at room temperature, and the biphenyl thus formed is accommodated in the gaps as anions (Bp 2− and Bp − ).