Inelastic neutron scattering from the quasi-one-dimensional conductor K1.75[Pt(CN)4]·1.5H2O

Neutron inelastic scattering has been used to study the longitudinal and one of the transverse acoustic phonons, propagating along the [001]¹ direction in triclinic K_1.75[Pt(CN)₄]·1.5H₂O. This material appears to be a quasi-one-dimensional conductor, with a commensurate distortion. We observe a reasonably well defined Kohn anomaly, which shows little temperature dependence between 80 and 300 K.     

Spin relaxation in the quasi-one-dimensional conductor Rb2Pt(CN)4(FHF)0.4

We analyze the electron paramagnetic resonance linewidth in Rb₂Pt(CN)₄(FHF)_0.4 as a function of temperature. Above 60 K, the results are interpreted as a superposition of spin-phonon and spin-spin relaxation effects. The dominant contribution to the relaxation rate l/T₂ has a dipolar origin in contrast to the spin-phonon origin observed in K₂Pt(CN)₄Br_0.3 · H₂O. This difference could arise from different anisotropy ratios of the transfer integrals. The influence of the interchain coupling is also discussed.     

Molecular distortion and ferroelasticity in K2Hg(CN)4 investigated by Raman scattering

The results of the temperature dependence of the Raman spectrum in K₂Hg(CN)₄ indicate that a trigonal distortion of the Hg(CN)⁼₄ ions exists in the room-temperature phase and thus its crystal structure is not cubic as previously reported. The ferroelasticity of the low-temperature phase and the phase transition at 110.5 K are apparently triggered by the molecular distortion.     

Spectra of K4Ru(CN)6

Luminescence of complex ions is a general phenomenon; the number of such complexes in various electronic configurations found to show emission is increasing rapidly. For some it has been possible to assign the emission as phosphorescence or as fluorescence, for others the proper assignment is as yet not clear.     

Cu／Fe（CN）6^3—／4—界面的动态FT—IR光谱

采用现场FT-IR光谱电化学研究了Cu/Fe(CN)_6~(3-/4-)界面的化学反应、电化学反应及其随电位、时间的变化关系,并从C≡N基振动频率的改变详细分析和讨论了Cu与Fe(CN)_6~(3-/4-)的作用及成膜过程。     

Study by X-ray crystallography and Mössbauer spectroscopy of CeFe(CN)6·5H2O and GdFe(CN)6·4H2O

From the X-ray crystallographic point of view, the environment of Fe in CeFe(CN)₆·5H₂O has higher octahedral symmetry than that in GdFe(CN)₆·4H₂O. The single Mössbauer absorption peak for CeFe(CN)₆·5H₂O indicates that the three t_2g levels are close to each other in energy due to a near-perfect octahedral Fe(CN)₆ unit. The doublet peak of of GdFe(CN)₆·4H₂O can be explained by assuming that the three t_2g levels are widely separated as a result of the distortion of the octahedral Fe(CN)₆ unit.     

Vibrational dynamics of the CN stretching mode of [Ru(CN)_6]~(4-) in D_2O studied by nonlinear infrared spectroscopy

We have studied vibrational dynamics of the T1u mode of the CN stretching mode of [Ru(CN)6 ]4- in D2O by infrared(IR) nonlinear spectroscopy such as an IR three-pulse photon echo experiment and polarization-sensitive IR pump-probe spectroscopy. The isotropic component of the pump-probe signal shows a bi-exponential decay with time constants of 0.8 ps and 20.8 ps. The fast and slow components correspond to the rapid equilibration between the T1u mode and the Raman active modes of the CN stretching mode and the vibrational population relaxation from the v=1 state of the T1u mode,respectively. Anisotropy of the pump-probe signal decays with a time constant of 3.1 ps,which is due to the time evolution of the superposition states of the triply degenerate T1u modes. Three pulse photon echo measurements showed that the time correlation function of the frequency fluctuation decays bi-exponentially with time constants of 80 fs and 1.4 ps. These time constants depend only on the solute and are independent of the solvent,whereas the amplitudes depend on both the solute and solvent.     

Interpretation of the ionization spectra of the cyanomethanes: CH3CN,CH2(CN)2 and C(CN)4

The valence ionization spectra of the mono-, di- and tetra-cyanomethane molecules are computed by Green function methods. As previously experienced on other cyano-derivatives of organic molecules, a hole-mixing effect is found. A partial reassignment of the spectrum is possible in the case of CH₂(CN)₂, whereas, due to the compactness of the spectrum and to the limitation of the basis set, an unambiguous assignment is not possible for C(CN)₄. The Koopmans ordering of the IP's is modified in two cases by the many-body perturbation.     

Effect of electric fields on photoluminescence of 4-(dicyanomethylene)-2-methyl- 6-(p-dimethylaminostyryl)-4H-pyran

Electric-field-induced photoluminescent variation has been observed from the red-emitting dopant, 4-(di cyanomethylene)-2-methyl-6-(p-dimethylaminostyryl)-4H-pyran (DCM). The layered structure of Al/tris-(8-hydroxyquinoline) aluminum (Alq)/DCM-doped Alq (Alq:DCM)/indium tin oxide studied, exhibits relatively enhanced red emission when a voltage is applied such that the electric field runs directly from the Alq:DCM layer to the Alq layer, and relatively enhanced green emission in the opposite direction of the field . This phenomenon is attributed to field-enhanced aggregation and permeation of DCM molecules due to the polarity of the molecule. PACS 78.55.Kz; 68.55.Ln; 85.60.Jb; 78.66.Qn; 78.20.Jq     

Analternative model for the conductivity behavior of K2Pt(CN)4Br0.3·3H2O

It is shown that the reordering of the bromine atoms into a new cubic lattice at low temperatures can produce the changes observed in the conductivity behavior of the mixed valence salt K₂Pt(CN)₄Br_0.32·3H₂O. The optical data are examined in terms of an RPA calculation of the dielectric response of the crystal and it is noted that a periodic potential can reproduce the observed structure in the imaginary part without the need for identifying the charge carriers.     

High pressure tuning of optical transitions in Mg[Pt(CN)4]·7H2O

Mg[Pt(CN)₄]·7H₂O belongs to the class of tetracyanoplatinates(II) which crystallize in columnar structures. In different M_x[Pt(CN)₄]·yH₂O (MCP) single crystals the in-chain Pt-Pt-distance R varies between 3.67 Å (NaCP) and 3.15 Å (MgCP). Two optical transitions can be observed in polarized emission with the electric field vector E either parallel or perpendicular to the columnar (c)-axis. Polarized emission spectra of MgCP are recorded under hydrostatic pressure up to p ≈ 18 kbar (at 295 K). The transition energy v?₆ can be tuned from 17,600 cm^-1 to about 12,000 cm^-1 (2.18-1.48 eV). The pressure induced red shift for the two transitions is: E 6 c: dv?₆/dp = -320±20 cm^-1/kbar, E ⊥ c: dv?_⊥/dp = -270±20 cm^-1/kbar. These values are discussed in the context of the known functional relationship (for ambient conditions) between v? and R.     

Electrical conduction studies on one-dimensional Cs2[Pt(CN)4](FHF)0.39 and Rb2[Pt(CN)4](FHF)0.40

Variable temperature (300-40 K) 4-probe d.c. conduction studies on Cs₂[Pt(CN)₄](FHF)_0.39 and Rb₂[Pt(CN)₄](FHF)_0.40 are described. In these salts T_3D occurs at a lower temperature than in K₂[Pt(CN)₄]Br_0.3·3H₂O and this is attributed to the absence of an inter-chain network of hydrogen bonded water molecules in the bifluorides.     

Formation of C60(2-) dianions in collisions between C60- and Na atoms

We have observed the formation of C2-60 and C2-70 in collisions between C(-)(60)/C(-)(70) and Na atoms. Cross sections for the electron transfer to the monoanion are determined to be 36+/-9 and 57+/-14 A(2) for C-60 and C-70, respectively. A simple model investigation suggests that the electron is transferred from a Na atom to a low-lying electronic state of the fullerene to form a dianion. The method leads to pico-ampere energetic beams of C60 dianions that can be used for spectroscopy and lifetime studies.     

2-对二甲氨基苯基-5-氟-6-吗啉苯并咪唑的合成及其光谱学性质研究

合成了一种新的取代苯并咪唑化合物 ,2 对二甲氨基苯基 5 氟 6 吗啉苯并咪唑 ,采用紫外 可见光谱、荧光光谱及荧光寿命等方法探讨了溶液pH值对该化合物吸收光谱的影响及其与 β 环糊精的作用。结果表明 ,pH >7 0时 ,该化合物在溶液中主要以中性分子状态存在 ,当 3 8相似文献   

Atomic structures of gallium-rich GaAs(001)-4×2 and GaAs(001)-4×6 surfaces

Scanning tunneling microscopy is applied for the first time to an atomic-resolution investigation of the 4×2 and 4×6 phases on a gallium-rich GaAs(001) surface obtained by molecular-beam epitaxy and migration-enhanced epitaxy. A unified structural model is proposed with consideration of the results of experiments and first-principles calculations of the total energy. In this model the 4×2 phase consists of two Ga dimers in the top layer and a Ga dimer in the third layer, and the 4×6 phase is matched to periodically arranged Ga clusters at the corners of a 4×6 unit cell on top of the 4×2 phase. Zh. éksp. Teor. Fiz. 111, 1858–1868 (May 1997)     

Electron energy loss spectrum of cyanogen on Pt (100)

Electron energy loss spectra for adsorbed cyanogen on Pt(100) are presented, and discussed in terms of possible models suggested by other techniques. Adsorbate induced loss features are found at 11 and 14 eV, and these are associated with levels below the Fermi level as observed in ultra-violet photoemission. As in the case of CO adsorption losses in the adsorbed phase occur at energies significantly larger than in the gas phase, indicating an upward shift of the final 2π¹ state due to mixing with metal orbitais. Thermal desorption studies of C₂N₂ on Pt clearly resolve α and β phases, but there is some controversy over whether the β phase involves mainly single CN units bonding to the metal, whether C₂N₂ is molecularly adsorbed, or whether paracyanogenlike structures form at the surface. The electron spectroscopic evidence is examined, and is shown on balance to support adsorption in some molecular form.     

Electron spectra of 4-substituted 1,2,4-triazine-3(2H)-thion(one)-5(4H)-ones

Substitution reactions in 1,2,4-triazine-3,5-thiones are studied. Their interaction with sodium nitrite in a hydrochloric acid medium and with N,N-dimethylcarbamoylbromide yields the 4-nitroso, azo, and carbamoyl derivatives of 1,2,4-triazines. The assignment of absorption bands in electron spectra of the compounds is discussed. Sumy State University, 2, Korsakov St., Sumy, 244007, Ukraine. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 1, pp. 112–115, January–February, 1997.