| 1. |
- Jonsson, D., et al.
(författare)
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Excited state polarizabilities in solution obtained by cubic response theory : Calculations on para-, ortho-, and meta-nitroaniline
- 1998
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Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 109:15, s. 6351-6357
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Tidskriftsartikel (refereegranskat)abstract
- We show that response theory implemented with a self-consistent reaction field theory model is a viable approach to simulate excited state polarizabilities of molecules in solution. The excited state polarizabilities are in this approach given by the double residue of the ground state cubic response functions, accounting for both equilibrium and nonequilibrium contributions to the interaction with the outer medium. The effects of the inertial polarization of the solvent on the polarizabilities of the solutes are shown to strongly depend on the solvent configuration, whether the solvent is in equilibrium or in nonequilibrium with the charge distribution of the investigated compound. The inertial polarization vector in the nonequilibrium solvent configuration represents the equilibrated solvent configuration when solvating the ground state of the solute. This inertial polarization vector is not in equilibrium with any of the excited states and therefore one observes a rather different behavior between nonequilibrium and equilibrium solvent descriptions of the solute. Illustrative calculations are presented for para-, meta-, and ortho-nitroanilines in gas and solution phases. Results have been compared with experimental data where available. © 1998 American Institute of Physics.
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| 2. |
- Luo, Y., et al.
(författare)
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Dielectric and optical properties of pure liquids by means of ab initio reaction field theory
- 1998
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Ingår i: Physical Review E. Statistical, Nonlinear, and Soft Matter Physics. - : American Physical Society (APS). - 1063-651X .- 1095-3787. ; 57:4, s. 4778-4785
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Tidskriftsartikel (refereegranskat)abstract
- A general Onsager-type reaction field theory approach for simulating dielectric and optical properties is proposed, thereby giving a unified description for both macroscopic and microscopic properties of pure liquids. A demonstration is given for ab initio computations of the refractive index, the density fluctuation of the refractive index, and the local field factors of benzene and acetonitrile in the liquid phase, showing good agreement with available experimental data.
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| 3. |
- Luo, Y., et al.
(författare)
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Some recent developments of high-order response theory
- 1998
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Ingår i: International Journal of Quantum Chemistry. - 0020-7608 .- 1097-461X. ; 70:1, s. 219-239
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Tidskriftsartikel (refereegranskat)abstract
- We review some recent developments of high-order response theory and illustrate the utility of this theory for a selection of nonlinear properties. © 1998 John Willey & Sons, Inc.
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| 4. |
- Norman, P., et al.
(författare)
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Hyperpolarizability depolarization ratios of nitroanilines
- 1997
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Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 107:21, s. 9063-9066
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Tidskriftsartikel (refereegranskat)abstract
- The depolarization ratios for the first hyperpolarizabilities of para-, meta-, and ortho-nitroanilines have been calculated in gas and solution phases. The results resolve ambiguities in the interpretation of experimental results for these quantities, and pinpoint the actual problems in previous simulations. It is argued that extraction of individual components of β of low symmetry molecules from experimental depolarization measurements alone is difficult, and that the support from simulations to extract the proper information is indispensable in most cases.
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| 5. |
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| 6. |
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| 7. |
- Eimert, K, et al.
(författare)
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Molecular cloning and expression of the large subunit of ADP-glucose pyrophosphorylase from barley (Hordeum vulgare) leaves
- 1997
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Ingår i: Gene. - 0378-1119 .- 1879-0038. ; 189:1, s. 79-82
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Tidskriftsartikel (refereegranskat)abstract
- A cDNA clone, blpl14, corresponding to the large subunit of ADP-glucose pyrophosphorylase (AGPase), has been isolated from a cDNA library prepared from leaves of barley (Hordeum vulgare L.). An open reading frame encodes a protein of 503 aa, with a calculated molecular weight of 54 815. The derived aa sequence contains a putative transit peptide sequence, required for targeting to plastids, and has a highly conserved positioning of critical Lys residues that are believed to be involved in effector binding. The derived aa sequence shows 97% identity with the corresponding protein from wheat, but only 36% identity with AGPase from E. coli. The blpl14 gene is expressed predominantly in leaves and to a lesser degree in seed endosperm, but not roots, of barley.
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| 8. |
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| 9. |
- Guo, J.-H., et al.
(författare)
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How the phenyle rings (benzene) act as building blocks in pi conjugated polymers
- 1998
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Ingår i: Advanced Light Source. - Berkeley : Ernest Orlando Lawrence Berkeley National Laboratory, University of California Berkeley, California, USA. ; , s. 129-132
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Organic conjugated polymers have the electronic structure of semiconductors and can be doped to become good conductors (1). Conjugated polymers are now used as active materials in a wide variety of prototype applications such as light emitting diodes [2] and organic transistors [3,4]. Most of the interesting chemistry and physics of conjugated polymers is associated with the details of the electronic structure at the valence and conduction band edges and, in this connection, various electron spectroscopies can be used as tools for diagnosis of the relevant electronic and geometric properties....
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| 10. |
- Guo, J.-H., et al.
(författare)
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Resonant and nonresonant x-ray scattering spectra of some poly(phenylenevinylene)s
- 1998
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Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 108:14, s. 5990-5996
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Tidskriftsartikel (refereegranskat)abstract
- The electronic structure of some poly(phenylenevinylene)s have been investigated by resonant and nonresonant x-ray inelastic scattering spectroscopies. The nonresonant as well as all resonant spectra for each polymer demonstrate benzene-like features, indicating a local character of the x-ray emission in which the phenyl ring acts as a building block. Theoretical simulations of x-ray energies and intensities taking the repeat unit as a model molecule of the polymer agree with the experimental spectra fairly well. The edges of the occupied bands have been identified in the nonresonant spectra of each polymer. By subtracting the emission energy of the highest occupied molecular orbital in the nonresonant spectrum from the core excitation energy in the resonant spectrum an alternative way to determine the optical band gap is obtained. As for free benzene the outer π band in the polymer spectra show a depletion of the emission going from the nonresonant to the resonant x-ray emission spectra. It is demonstrated that this transition, which is strictly symmetry forbidden for free benzene, becomes effectively forbidden in the polymer case as a result of strong interference effects, and it is argued that this is the general case for resonant x-ray emission of conjugated polymers as far as the frozen orbital approximation holds.
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| 11. |
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| 12. |
- Jiang, Z. K, et al.
(författare)
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Lifetimes of Rydberg Levels In the Perturbed 6snp P-1,3(1) Series of Ybi
- 1995
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Ingår i: Physics Letters. Section A: General, Atomic and Solid State Physics. - : Elsevier BV. - 0375-9601. ; 204:1, s. 49-53
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Tidskriftsartikel (refereegranskat)abstract
- Using two methods: (1) three-step excitation and (2) single UV photon excitation in an atomic beam with direct observation of the decay of the fluorescence light, we have measured the lifetimes of the Rydberg levels of YbI belonging to the perturbed series 6snp J = 1 levels. The measured values have been interpreted by the multichannel quantum defect theory (MQDT).
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| 13. |
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| 14. |
- Jonsson, D., et al.
(författare)
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Calculations of circular intensity differences in electric-field-induced second harmonic generation
- 1998
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Ingår i: Chemical Physics Letters. - : Elsevier BV. - 0009-2614 .- 1873-4448. ; 288:2-4, s. 371-376
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Tidskriftsartikel (refereegranskat)abstract
- Ab initio calculations of electric-field induced second-harmonic generation for chiral molecules are presented. The calculations employ cubic response theory and take into account electric-dipole, electric-quadrupole and magnetic-dipole interactions, which result in an intensity dependence on the helicity of the light. The circular intensity difference is calculated for the chiral molecules twisted ethylene, trans-1,2-dimethylcyclopropane and methyloxirane. The calculated circular intensity differences are small - being of the order of 10-4-10-3 - but such electric-field induced second harmonic generation intensity dependencies should be experimentally detectable.
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| 15. |
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| 16. |
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| 17. |
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| 18. |
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| 19. |
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| 20. |
- Luo, Y., et al.
(författare)
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Molecular length dependence of optical properties of hydrocarbon oligomers
- 1998
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Ingår i: Chemical Physics Letters. - : Elsevier BV. - 0009-2614 .- 1873-4448. ; 285:3-4, s. 160-163
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Tidskriftsartikel (refereegranskat)abstract
- It is demonstrated that common power law dependencies for the energy gap, the polarizability, and the hyperpolarizability can be obtained for shorter hydrocarbon oligomers if the molecular length is used as the basic structural parameter.
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| 21. |
- Luo, Y., et al.
(författare)
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Saturation of the optical band gap and properties of five-membered heteroaromatic oligomers
- 1998
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Ingår i: Journal of Physical Chemistry B. - 1089-5647. ; 102:10, s. 1710-1712
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Tidskriftsartikel (refereegranskat)abstract
- The saturation behavior of the optical band gap and dynamic (hyper)polarizabilities of five-membered heteroaromatic oligomers - oligothiophene, oligofuran and oligopyrrole - has been studied by means of ab initio response theory in the random phase approximation. The calculated optical band gap for the oligomers and the extrapolated band gap for the polymers are found to be within 0.2 eV of available experimental data. The calculated saturation lengths of the band gaps are in good agreement with experimental determinations. The saturation of the polarizabilities is found to be slower than that of the band gaps, especially when dispersion is taken into account. The calculations indicate that previous experimental observation of fast convergence of the optical properties of oligothiophenes may be due to disorder in the samples.
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| 22. |
- Mohan, R. K., et al.
(författare)
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Delayed single-photon self-interference
- 1998
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Ingår i: Physical Review A (Atomic, Molecular and Optical Physics). - 1050-2947. ; 58:6
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Tidskriftsartikel (refereegranskat)abstract
- It has been suggested that a single photon can interfere with itself even if the difference between the two paths in the interferometer is larger than the “length” of the photon [Kessel’ and Moiseev, JETP Lett. 58, 81 (1993)]. The interference is regained by detecting the photons using a photon-echo process, where the absorbing atoms will, effectively, act as narrow-band filters. Such an experiment has several unique features. For example, single photons are used to carry out what is generally regarded as a multiphoton process; the absorption of a single photon can be regarded as separated into two different moments in time; the fact that the single-photon interference is regained using atoms acting as narrow-band filters as the detector means that the control of the detection process is quite different from cases where electronic (or possibly photographic) detection is used to register the interference etc. In general, interference and absorption are combined and intertwined in the experiment, which is discussed in this paper, in a way that has not been done before. In the present paper the possibility to carry out such an experiment in practice is investigated in some detail. The signal strength is explicitly calculated and the results are compared with our experimental data for the case of many interfering photons. We imply that this result can readily be extrapolated to the single-photon situation. We analyze the material parameters that are important for carrying out the experiment and give specific examples of some suitable materials.
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| 23. |
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| 24. |
- Skytt, P, et al.
(författare)
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Role of screening and angular distributions in resonant x-ray emission of CO
- 1997
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Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics. - 1050-2947. ; 55:1, s. 134-145
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Tidskriftsartikel (refereegranskat)abstract
- Resonantly excited carbon and oxygen x-ray-emission spectra of gaseous carbon monoxide are presented. Emission spectra obtained with selective excitation to the pi* valence orbital and to various Rydberg levels are compared to satellite-free nonresonant spectra. Screening effects caused by the excited electron, creating energy shifts and intensity variations in the resonant spectra compared to the nonresonant spectra, are observed, as well as an angular dependence of the resonantly excited spectra. The experimental spectra are compared to simulated spectra where the vibronic part is computed by means of a lifetime-vibrational interference formalism. The electronic intensities are analyzed by a separate-state, self-consistent-held method and a formalism for resonant inelastic x-ray scattering, focusing On screening and angular dependence.
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| 25. |
- Skytt, P, et al.
(författare)
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Role of screening and angular distributions in resonant x-ray emission of CO
- 1997
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Ingår i: PHYSICAL REVIEW A. - : AMER INST PHYSICS. - 1050-2947. ; 55:1, s. 134-145
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Resonantly excited carbon and oxygen x-ray-emission spectra of gaseous carbon monoxide are presented. Emission spectra obtained with selective excitation to the pi* valence orbital and to various Rydberg levels are compared to satellite-free nonresonant s
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