Are the triple surface plasmon resonances in Zn nanoparticles true?

It has been experimentally and numerically confirmed that zinc (Zn) nanoparticles (NPs) dispersed in silica exhibit two optical extinction peaks around ∼250 nm (1st peak) and ∼1050 nm (2nd peak), both of which were ascribed to surface plasmon resonances (SPRs) in the broad sense, i.e., the dual SPRs. Recently, Kuiri and Majhi (KM) observed the 3rd peak around ∼900 nm by calculations, and proposed the triple SPRs for Zn NPs without any experimental confirmation. This paper claims that the 3rd peak has never been observed in any experiments nor in any calculations except given by KM. They justified the triple resonances from an approximated SPR criterion, ε 1Zn(ω) + 2ε 1SiO2 (ω) = 0, which is not valid for non-idealized metals like Zn, because the imaginary part of the dielectric function ε 2Zn(ω) is not negligible. Instead, a rigorous SPR criterion predicts the dual resonances only. From comparisons with ab initio band calculations, the 1st and 2nd extinction peak are ascribed to resonantly enhanced inter-band transitions (so-called electronic resonance) and intra-band transitions (SPR in the narrow sense), respectively. Since either of the peaks arises from the resonant enhancement due to the dielectric function, both the peaks are regarded as SPRs in the broad sense, i.e. the dual SPRs.

Calculations of Electron Inelastic Mean Free Paths. XI. Data for Liquid Water for Energies from 50 eV to 30 keV.

We calculated electron inelastic mean free paths (IMFPs) for liquid water from its optical energy-loss function (ELF) for electron energies from 50 eV to 30 keV. These calculations were made with the relativistic full Penn algorithm (FPA) that has been used for previous IMFP and electron stopping-power calculations for many elemental solids. We also calculated IMFPs of water with three additional algorithms: the relativistic single-pole approximation (SPA), the relativistic simplified SPA, and the relativistic extended Mermin method. These calculations were made using the same optical ELF in order to assess any differences of the IMFPs arising from choice of the algorithm. We found good agreement among the IMFPs from the four algorithms for energies over 300 eV. For energies less than 100 eV, however, large differences became apparent. IMFPs from the relativistic TPP-2M equation for predicting IMFPs were in good agreement with IMFPs from the four algorithms for energies between 300 eV and 30 keV but there was poorer agreement for lower energies. We calculated values of the static structure factor as a function of momentum transfer from the FPA. The resulting values were in good agreement with results from first-principles calculations and with inelastic X-ray scattering spectroscopy experiments. We made comparisons of our IMFPs with earlier calculations from authors who had used different algorithms and different ELF data sets. IMFP differences could then be analyzed in terms of the algorithms and the data sets. Finally, we compared our IMFPs with measurements of IMFPs and of a related quantity, the effective attenuation length (EAL). There were large variations in the measured IMFPs and EALs (as well as their dependence on electron energy). Further measurements are therefore required to establish consistent data sets and for more detailed comparisons with calculated IMFPs.

Extended Mermin method for calculating the electron inelastic mean free path.

We propose an improved method for calculating electron inelastic mean free paths (IMFPs) in solids from experimental energy-loss functions based on the Mermin dielectric function. The "extended Mermin" method employs a nonlimited number of Mermin oscillators and allows negative oscillators to take into account not only electronic transitions, as is common in the traditional approaches, but also infrared transitions and inner shell electron excitations. The use of only Mermin oscillators naturally preserves two important sum rules when extending to infinite momentum transfer. Excellent agreement is found between calculated IMFPs for Cu and experimental measurements from elastic peak electron spectroscopy. Notably improved fits to the IMFPs derived from analyses of x-ray absorption fine structure measurements for Cu and Mo illustrate the importance of the contribution of infrared transitions in IMFP calculations at low energies.

Cross-Cultural Variations in Probability Judgment Accuracy: Beyond General Knowledge Overconfidence?

Previous studies have revealed surprising and persistent cross-cultural variations in overconfidence, whereby respondents in some Asian cultures (e.g., Chinese) exhibit markedly higher degrees of overconfidence than respondents in other cultures (e.g., in the United States and Japan). Most of those demonstrations have entailed general knowledge tasks (e.g., answering questions such as whether Europe is larger than Australia). The present studies sought to determine whether such cross-cultural variations extend to judgments about the kinds of events that bear upon more common practical decisions and to aspects of accuracy other than overconfidence. Subjects in Taiwan, Japan, and the United States made probabilistic differential diagnoses of fictional diseases in a stochastic artificial ecology. Results revealed that previously observed cross-cultural variations do indeed generalize. The data were also informative about several potential accounts for such variations, e.g., arguing against a proposal that they rest on different emphases on discrimination rather than calibration, but consistent with the influences of culture-specific cognitive customs, including responsiveness to explicitly displayed information, regardless of its presumed validity. Copyright 1998 Academic Press.

[Does altruism reach beyond the in group?: a social orientation approach].

The experiment of this paper studied the role social orientation would play in double-dilemma situations. In a double-dilemma situation, social dilemmas exist both between and within groups; a cooperation choice at the within-groups level is considered a defection choice at the between-groups level, and vice versa. Using such a situation, whether "others" in other-orientedness are limited to those of the ingroup or include those of a competing group was examined. Each of 132 college students played both an ordinary social dilemma game and a double-dilemma game, with equivalent incentive structures. Subjects' social orientation was measured a few days after the experiment. Results indicated that other-oriented subjects thought only about ingroup members, and did not care much about the others. Furthermore, social orientation did not affect whether subjects acted similarly or differently for the two dilemma situations. Therefore, social orientation approach to intergroup conflicts apparently had its limitations.

[Confidence and accuracy of mental judgments].

Problems consisted of two categories of questions, of general knowledge and forecasting future events. Given each question, the subjects chose a more likely answer from the given two alternatives, rated their own confidence on the correctness of the choice, and then, assessed the hit-rate of the classmates. The major result is as follows. The difference between average confidence and average hit-rate was small, namely, calibration was good, for problems of both general knowledge and familiar future events. On the other hand, calibration was poor for problems of accidental future events. In other words, the more available knowledge, the better calibration is. In discussion we proposed "a model of retrieval and generation", which could explain our results for the problems of general knowledge. Results for problems of future events suggest that the subjects possibly used a certain model to make their probability judgments. On the basis of our results and with our discussion, we found the phenomenon that people believe themselves to make mental judgments better than the average. We call the phenomenon "self-superiority phenomenon".