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91.
We present fast and efficient tight-binding (TB) methods for simulating scanning tunneling microscopy (STM) imaging of adsorbate molecules on ultrathin insulating films. Due to the electronic decoupling of the molecule from the metal surface caused by the presence of the insulating overlayer, STM can be used to image the frontier molecular orbitals of the adsorbate. These images can be simulated with a very efficient scheme based on hopping integrals which also enables the analysis of phase shifts in the STM current. Au-pentacene complex adsorbed on a NaCl bilayer on Cu substrate provides an intricate model system which has been previously studied both experimentally and theoretically. Our calculations indicate that the complicated shape of the molecular orbitals may cause multivalued constant current surfaces - leading to ambiguity of the STM image. The results obtained using the TB methods are found to be consistent with both DFT calculations and experimental data. 相似文献
92.
Vincent L.Y. Loke Timo A. Nieminen Norman R. Heckenberg Halina Rubinsztein-Dunlop 《Journal of Quantitative Spectroscopy & Radiative Transfer》2009,110(14-16):1460-1471
We present a method of incorporating the discrete dipole approximation (DDA) method with the point matching method to formulate the T-matrix for modelling arbitrarily shaped microsized objects. The T-matrix elements are calculated using point matching between fields calculated using vector spherical wave functions and DDA. When applied to microrotors, their discrete rotational and mirror symmetries can be exploited to reduce memory usage and calculation time by orders of magnitude; a number of optimization methods can be employed based on the knowledge of the relationship between the azimuthal mode and phase at each discrete rotational point, and mode redundancy from Floquet's theorem. A ‘reduced-mode’ T-matrix can also be calculated if the illumination conditions are known. 相似文献
93.
Algora A Jordan D Taín JL Rubio B Agramunt J Perez-Cerdan AB Molina F Caballero L Nácher E Krasznahorkay A Hunyadi MD Gulyás J Vitéz A Csatlós M Csige L Aysto J Penttilä H Moore ID Eronen T Jokinen A Nieminen A Hakala J Karvonen P Kankainen A Saastamoinen A Rissanen J Kessler T Weber C Ronkainen J Rahaman S Elomaa V Rinta-Antila S Hager U Sonoda T Burkard K Hüller W Batist L Gelletly W Nichols AL Yoshida T Sonzogni AA Peräjärvi K 《Physical review letters》2010,105(20):202501
The β feeding probability of (102,104,105,106,107)Tc, 105Mo, and 101Nb nuclei, which are important contributors to the decay heat in nuclear reactors, has been measured using the total absorption technique. We have coupled for the first time a total absorption spectrometer to a Penning trap in order to obtain sources of very high isobaric purity. Our results solve a significant part of a long-standing discrepancy in the γ component of the decay heat for 239Pu in the 4-3000 s range. 相似文献
94.
Grahn T Dewald A Möller O Julin R Beausang CW Christen S Darby IG Eeckhaudt S Greenlees PT Görgen A Helariutta K Jolie J Jones P Juutinen S Kettunen H Kröll T Krücken R Le Coz Y Leino M Leppänen AP Maierbeck P Meyer DA Melon B Nieminen P Nyman M Page RD Pakarinen J Petkov P Rahkila P Saha B Sandzelius M Sarén J Scholey C Uusitalo J 《Physical review letters》2006,97(6):062501
Lifetimes of prolate intruder states in 186Pb and oblate intruder states in 194Po have been determined by employing, for the first time, the recoil-decay tagging technique in recoil distance Doppler-shift lifetime measurements. In addition, lifetime measurements of prolate states in 188Pb up to the 8+ state were carried out using the recoil-gating method. The B(E2) values have been deduced from which deformation parameters |beta2|=0.29(5) and |beta2|=0.17(3) for the prolate and the oblate bands, respectively, have been extracted. The results also shed new light on the mixing between different shapes. 相似文献
95.
G. D. Dracoulis P. M. Davidson G. J. Lane A. P. Byrne T. Kibédi P. Nieminen A. N. Wilson H. Watanabe 《The European Physical Journal A - Hadrons and Nuclei》2009,40(2):127-130
Excited states in 208Fr have been identified using the 197Au(16O, 5n)208Fr reaction and a variety of time-correlated g \gamma -ray and conversion electron spectroscopic techniques. Transitions above and below a t \tau = 623(16) ns 10- isomer are placed in the level scheme. This isomer is analogous to that observed in the odd-odd isotone 206At for which additional spectroscopic information is also obtained, including a precise lifetime of t \tau = 1173(30) ns. The g \gamma -rays assigned to 208Fr are the same as the main transitions erroneously assigned to 209Fr in previous work. 相似文献
96.
It has been suggested that radially polarized beams can be used to improve the performance of optical tweezers, with reduced scattering force resulting from both the polarization and the dark center of the beam [Opt. Lett. 32, 1839 (2007)]. We calculate the forces on particles in such traps, using rigorous electromagnetic theory, comparing the results with azimuthally polarized beam, circularly polarized LG 01 beams, and Gaussian beams. Our results agree qualitatively with Opt. Lett. 32, 1839 (2007), but differ quantitatively. 相似文献
97.
Sari Mkinen Jaakko Hiidenhovi Xin Huang Amanda dos Santos Lima Luciana Azevedo Jari Setl Anna-Liisa Vlimaa Pirjo Mattila Daniel Granato 《Molecules (Basel, Switzerland)》2022,27(18)
This study aimed to produce bioactive protein hydrolysates from undervalued fish, namely Baltic herring, and its filleting by-products. Protein hydrolysates were produced with Alcalase and Flavourzyme to achieve effective hydrolysis. The hydrolysates were evaluated for chemical composition, molecular weight distribution, antioxidant capacity, dipeptidyl-peptidase 4 (DPP4) inhibitory activity, effects on cell proliferation and surface hydrophobicity. The protein content of the hydrolysates was high, from 86% to 91% (dm), while the fat content was low, from 0.3% to 0.4% (dm). The hydrolysates showed high DPP4 inhibition activities with IC50 values from 5.38 mg/mL to 7.92 mg/mL. The scavenging activity of the hydrolysates towards DPPH was low, but an intermediate Folin–Ciocalteu reducing capacity and Cu2+ chelating ability was observed. The solid phase extraction with Sep-Pak C18 cartridges increased the DPP4 inhibition activity and antioxidant capacity, indicating peptides’ crucial role in the bioactivities. The cytotoxicity of the hydrolysates was evaluated on the HCT8, IMR90, and A549 cell lines. The hydrolysates inhibited cell growth in the cancer and normal cells, although they did not reduce cell viability and were not lethal. Overall, our results indicate that protein hydrolysates from Baltic herring have potential as health-promoting foods and nutraceuticals, especially for enhancing healthy blood glucose regulation. 相似文献
98.
99.
100.
K. J. Jalkanen V. Würtz Jürgensen A. Claussen A. Rahim G. M. Jensen R. C. Wade F. Nardi C. Jung I. M. Degtyarenko R. M. Nieminen F. Herrmann M. Knapp‐Mohammady T. A. Niehaus K. Frimand S. Suhai 《International journal of quantum chemistry》2006,106(5):1160-1198
We report on our work with vibrational absorption, vibrational circular dichroism, Raman scattering, Raman optical activity, and surface‐enhanced Raman spectroscopy to study protein and DNA structure, hydration, and the binding of ligands, drugs, pesticides, or herbicides via a combined theoretical and experimental approach. The systems we have studied systematically are the amino acids (L ‐alanine, L ‐tryptophan, and L ‐histidine), peptides (N‐4271 acetyl L ‐alanine N′‐methyl amide, N‐acetyl L ‐tryptophan N′‐methyl amide, N‐acetyl L ‐histidine N′‐methyl amide, L ‐alanyl L ‐alanine, tri‐L ‐serine, N‐acetyl L ‐alanine L ‐proline L ‐tyrosine N′‐methyl amide, Leu‐enkephalin, cyclo‐(gly‐L ‐pro)3, N‐acetyl (L ‐alanine)n N′‐methyl amide), 3‐methyl indole, and a variety of small molecules (dichlobenil and 2,6‐dochlorobenzamide) of relevance to the protein systems under study. We have used molecular mechanics, the SCC‐DFTB, SCC‐DFTB+disp, RHF, MP2, and DFT methodologies for the modeling studies with the goal of interpreting the experimentally measured vibrational spectra for these molecules to the greatest extent possible and to use this combined approach to understand the structure, function, and electronic properties of these molecules in their various environments. The application of these spectroscopies to biophysical and environmental assays is expanding, and therefore a thorough understanding of the phenomenon from a rigorous theoretical basis is required. In addition, we give some exciting and new preliminary results which allow us to extend our methods to even larger and more complex systems. The work presented here is the current state of the art to this ever and fast changing field of theoretical spectroscopic interpretation and use of VA, VCD, Raman, ROA, EA, and ECD spectroscopies. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2006 相似文献