| 1. |
- Zhang, Shi-Li, et al.
(författare)
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Abnormal anti-Stokes Raman scattering of carbon nanotubes
- 2002
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 66:3
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Tidskriftsartikel (refereegranskat)abstract
- Abnormal anti-Stokes Raman scattering (AASR) was unambiguously observed in carbon nanotubes (CNT's). In contrast to traditional Raman scattering theory, the absolute value of the Raman frequency of the anti-Stokes peak is not the same as that of the corresponding Stokes peak. It was demonstrated that AASR scattering originates from the unique nanoscale cylindrical structure of CNT's that can be considered naturally as a graphite structure with an intrinsic defect from its rolling. The double-resonance Raman scattering theory was applied to interpret the scattering mechanism of the AASR phenomenon successfully and quantitatively.
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| 2. |
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| 3. |
- Schnadt, J, et al.
(författare)
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Excited-state charge transfer dynamics in systems of aromatic adsorbates on TiO2 studied with resonant core techniques
- 2003
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Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 119:23, s. 12462-12472
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Tidskriftsartikel (refereegranskat)abstract
- Resonant core spectroscopies are applied to a study of the excited electron transfer dynamics on a low-femtosecond time scale in systems of aromatic molecules (isonicotinic acid and bi-isonicotinic acid) adsorbed on a rutile TiO2(110) semiconductor surface. Depending on which adsorbate state is excited, the electron is either localized on the adsorbate in an excitonic effect, or delocalizes rapidly into the substrate in less than 5 fs (3 fs) for isonicotinic acid (bi-isonicotinic acid). The results are obtained by the application of a variant of resonant photoemission spectroscopy. (C) 2003 American Institute of Physics.
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| 4. |
- Sun, S. G., et al.
(författare)
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Studies on a series of rhenium(I) bipyridyl photosensitive dyes
- 2004
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Ingår i: Youji huaxue. - 0253-2786. ; 24:8, s. 953-956
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Tidskriftsartikel (refereegranskat)abstract
- A series of rhemium(I) 2,2'-bipyridyl complexes [fac-(4,4'-di-COOEt-bpy)Re(CO)(3)(Xpy)PF6] (bpy = 2, 2'-bipyridine; py = pyridine; X = 3-methyl, 3-hydroxy, 3-amino, H) were synthesized. Their electrochemical properties, ground state electronic spectra and emission spectra were studied in acetonitrile. As the X group became more electron donating from H to 3-methyl, 3-hydroxy or 3-amino, the Re(II/I) oxidation potentials declined, the MLCT absorption maximum of the complex was changed little, the emission maximum blue-shifted, and the emission intensity and the fluorescence lifetime were decreased.
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| 5. |
- Zhang, L., et al.
(författare)
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Effects of intense laser irradiation on Raman intensity features of carbon nanotubes
- 2002
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 65:7
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Tidskriftsartikel (refereegranskat)abstract
- The effect of intense laser irradiation on the features of Raman intensity of carbon nanotubes (CNT's) has been examined. The intensity of the D band decreases and the relative intensity between the G peaks changes with increasing laser power density (LPD) and remain unchanged with subsequent decrease in LPD. This behavior is different from the reversible variation of the G band frequency in the same process of power increase and subsequent decrease. It has been demonstrated that such irreversible change in intensity features originates from sample purification. This result suggests a simple and fast CNT purification method using intense laser irradiation.
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| 6. |
- Andersson, J. O., et al.
(författare)
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THERMO-CALC & DICTRA, computational tools for materials science
- 2002
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Ingår i: Calphad. - 0364-5916 .- 1873-2984. ; 26:2, s. 273-312
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Tidskriftsartikel (refereegranskat)abstract
- Software for calculation of phase diagrams and thermodynamic properties have been developed since the 1970's. Software and computers have now developed to a level where such calculations can be used as tools for material and process development. In the present paper some of the latest software developments at Thermo-Calc Software are presented together with application examples. It is shown how advanced thermodynamic calculations have become more accessible since: - A more user-friendly windows version of Thermo-Calc, TCW, has been developed. - There is an increasing amount of thermodynamic databases for different materials available. - Thermo-Calc can be accessed from user-written software through several different programming interfaces are available which enables access to the thermodynamic software from a user-written software. Accurate data for thermodynamic properties and phase equilibria can then easily be incorporated into software written in e.g. C++, Matlab and FORTRAN. Thermo-Calc Software also produces DICTRA, a software for simulation of diffusion controlled phase transformations. Using DICTRA it is possible to simulate processes such as homogenization, carburising, microsegregation and coarsening in multicomponent alloys. The different models in the DICTRA software are briefly presented in the present paper together with some application examples.
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| 7. |
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| 8. |
- Bruton, Joseph D., et al.
(författare)
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Ryanodine receptors of pancreatic beta-cells mediate a distinct context-dependent signal for insulin secretion
- 2003
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Ingår i: The FASEB Journal. - : Wiley. - 0892-6638 .- 1530-6860. ; 17:2, s. 301-303
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Tidskriftsartikel (refereegranskat)abstract
- The ryanodine (RY) receptors in beta-cells amplify signals by Ca2+-induced Ca2+ release (CICR). The role of CICR in insulin secretion remains unclear in spite of the fact that caffeine is known to stimulate secretion. This effect of caffeine is attributed solely to the inhibition of cAMP-phosphodiesterases (cAMP-PDEs). We demonstrate that stimulation of insulin secretion by caffeine is due to a sensitization of the RY receptors. The dose-response relationship of caffeine-induced inhibition of cAMP-PDEs was not correlated with the stimulation of insulin secretion. Sensitization of the RY receptors stimulated insulin secretion in a context-dependent manner, that is, only in the presence of a high concentration of glucose. This effect of caffeine depended on an increase in [Ca2+]i. Confocal images of beta-cells demonstrated an increase in [Ca2+]i induced by caffeine but not by forskolin. 9-Methyl-7-bromoeudistomin D (MBED), which sensitizes RY receptors, did not inhibit cAMP-PDEs, but it stimulated secretion in a glucose-dependent manner. The stimulation of secretion by caffeine and MBED involved both the first and the second phases of secretion. We conclude that the RY receptors of beta-cells mediate a distinct glucose-dependent signal for insulin secretion and may be a target for developing drugs that will stimulate insulin secretion only in a glucose-dependent manner.
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| 9. |
- Du, Jiangfeng, et al.
(författare)
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An experimental observation of geometric phases for mixed states using NMR interferometry
- 2003
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 91:10, s. 100403-
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Tidskriftsartikel (refereegranskat)abstract
- Examples of geometric phases abound in many areas of physics. They offer both fundamental insights into many physical phenomena and lead to interesting practical implementations. One of them, as indicated recently, might be an inherently fault-tolerant quantum computation. This, however, requires to deal with geometric phases in the presence of noise and interactions between different physical subsystems. Despite the wealth of literature on the subject of geometric phases very little is known about this very important case. Here we report the first experimental study of geometric phases for mixed quantum states. We show how different they are from the well understood, noiseless, pure-state case.
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