bluuebunny/crossref_metadata_2025 huggingface dataset:
Massive Early Cretaceous volcanic activity in the Nauru Basin related to emplacement of the Ontong Java Plateau
Authors: Mochizuki Kimihiro , Coffin Millard F. , Eldholm Olav , Taira Asahiko
Published: October 2005

The Mesozoic Nauru Basin in the western Pacific was created by seafloor spreading in Late Jurassic and Early Cretaceous time and was subsequently affected by Early Cretaceous flood volcanism approximately contemporaneous with emplacement of the nearby ∼120 Ma Ontong Java Plateau (OJP). To investigate structure and stratigraphy of the basin, we completed a coincident multichannel seismic reflection (MCS) and refraction (sonobuoy) transect from the center of the Nauru Basin to the eastern flank of the OJP in 1998 aboard R/V Hakuho Maru. Along the transect we identify four segments of distinct crustal structure: C1, a thick igneous complex with no observable refractions; C2, basaltic sills and flows, C3, faulted sediment and rock near the flank of the OJP; and C4, the OJP. On data from seven sonobuoys we observe P‐wave refraction arrivals with apparent velocities of ∼6.0 km/s in each segment except C1. Sonobuoy data from segment C1 show no refractions, a common phenomenon in the northern Nauru Basin. We consider that the structure in segment C1 is most representative of typical Nauru Basin crust, and we estimate the volume of the thick igneous complex from discrepancies between actual seafloor depths and those predicted by an age‐depth model, which commonly exceed 1000 m. We selected an appropriate model by comparing observed seafloor depths at drill holes in the Mesozoic Pigafetta and East Mariana basins where Cretaceous igneous complexes are thin or absent. From an empirical density‐velocity relation, we calculated a basalt loading factor of 780 m/s for subsidence of the Late Jurassic‐Early Cretaceous oceanic crust. We then applied the factor to estimate the thickness of the younger Early Cretaceous igneous complex, using previous seismic reflection (Charcot 2), drilling (DSDP Site 462), and wide‐angle seismic data from DSDP Site 462 as controls. We estimate that the igneous complex is thickest, ∼5500 m, in the center of the basin and that the total volume of the Early Cretaceous igneous complex is 3.3 × 106 km3.
Current‐voltage relationship in downward field‐aligned current region
Authors: Cran‐McGreehin Alexandra P. , Wright Andrew N.
Published: October 2005

Field‐aligned electrons accelerated upward from the ionosphere to the magnetosphere are the principal charge carriers in the auroral downward field‐aligned current region. Current densities, typically of the order of a few μAm−2, are sustained by potential drops of several 100 V up to a few kV. This paper uses a model presented in a separate paper in this special section (Cran‐McGreehin and Wright, 2005) to obtain an analytical nonlinear current‐voltage relationship for the downward current, which is complimentary to the well‐known linear current‐voltage relation for the upward current region (Knight, 1973). Exact and approximate current‐voltage relations are given. These relations are compared with FAST observations and show good agreement.
A numerical study of the western Cosmonaut polynya in a coupled ocean–sea ice model
Authors: Prasad T. G. , McClean Julie L. , Hunke Elizabeth C. , Semtner Albert J. , Ivanova Detelina
Published: October 2005

Employing results from a 0.4°, 40‐level fully global, coupled ocean–sea ice model, we investigated the role of physical processes emanating from atmosphere, ocean, and ice in the initiation, maintenance, and termination of a sensible heat polynya with a focus on the western Cosmonaut polynya that occurred during May–July 1999. The Cosmonaut polynya first appeared in early May 1999 in the form of an ice‐free embayment, transformed into an enclosed polynya on 5–9 July, and disappeared by late July, when the ice from the surrounding regions began to encircle the embayment. Except for the differences in ice concentrations, the time of appearance, size, and shape of the Cosmonaut polynya simulated by the model are in approximate agreement with the Special Sensor Microwave/Imager (SSM/I) observations. Between May and July 1999 the Cosmonaut Sea experienced two synoptic storms, both lasting ∼5 days. Followed by the passage of the first storm on 12–19 June, there was a remarkable growth in the size of the embayment by 21 × 103 km2. Associated with this, the sea surface temperature (SST) rose by 0.15°C, the upward heat flux jumped from 5 to 94 W m−2, and a net freshwater flux into the ocean increased by 2 cm d−1. By running the model simulation with a 20% wind speed increase, it is demonstrated that the twofold increase in SST and upward heat flux increased the embayment area by 15 × 103 km2 and decreased the ice concentration by approximately 10% from the control run. A similar, but somewhat weaker wind event that took place on 30 June to 10 July had less influence on the embayment area although the upward heat flux (65 W m−2) was comparable to the first event. By examining the vertical displacement of the −1.6°C isotherm depth prior to, during, and after these two storms, we demonstrate that the impetus provided by these storms was able to raise the −1.6°C isotherm depth by 30 m through wind‐driven mixing, making sufficient oceanic heat input from beneath the mixed layer available to prevent freezing and/or delay ice formation while ice in the adjacent regions continued to grow. A sudden shift in the ice drift direction from southwest to northeast (3 July) followed by the second storm, accompanied by large air‐sea temperature differences, caused the enclosure of the embayment, subsequent formation of the polynya, and its termination.
Melting in the Hawaiian plume at 1–2 Ma as recorded at Maui Nui: The role of eclogite, peridotite, and source mixing
Authors: Gaffney Amy M. , Nelson Bruce K. , Blichert‐Toft Janne
Published: October 2005

The volcanoes of Maui Nui (West Moloka'i, East Moloka'i, Lana'i, West Maui, Haleakala, and Kaho'olawe) record Hawaiian magmatism at ∼1–2 Ma. Lavas from these volcanoes nearly span the compositional range erupted from all the Hawaiian volcanoes over the past 5 Myr and represent both the Kea and Ko'olau compositional end‐members of Hawaiian lavas. Many aspects of major and trace element and isotope compositions of Hawaiian shield‐stage lavas are consistent with ancient, recycled oceanic lithosphere in the plume sources of Kea‐ and Ko'olau‐type magmas (Lassiter and Hauri, 1998; Blichert‐Toft et al., 1999). Hypotheses that describe the compositional range of Hawaiian lavas as originating from ancient oceanic lithosphere in the Hawaiian plume implicitly or explicitly infer lithologic heterogeneity in the plume. We present trace element models for the origin of these end‐members that explicitly address the petrologic complexities of melting eclogite (derived from ancient oceanic lithosphere) in the plume. Trace element (La/Nb, Sm/Yb, Sm/Hf, and Sm/Nb), major element, and isotope compositions of Lana'i, which erupts dominantly Ko'olau‐type lavas, are consistent with the origin of these lavas in large‐degree (∼60–70%) melts of ancient upper oceanic crust (basalt + sediment) that mix with plume‐derived Haleakala‐type melts. Trace element (Sm/Yb, Hf/Zr, and Hf/Nb) and isotope compositions of West Maui and East Moloka'i, which erupt dominantly Kea‐type magmas, are consistent with an origin in ancient depleted oceanic lithosphere that has been refertilized with moderate‐degree melts (10–30%) of associated crustal gabbro. The physical mechanisms (melt‐melt versus melt‐solid mixing) through which the oceanic crustal components melt and mix within the plume lead to the generation of isotopically homogeneous Kea‐type lavas and isotopically heterogeneous Ko'olau‐type lavas. The volcanoes of Maui Nui record the exhaustion of the Ko'olau component and the initiation of the Kea component as dominant compositional end‐members in the Hawaiian plume.
Cross‐formational flow and salinity sources inferred from a combined study of helium concentrations, isotopic ratios, and major elements in the Marshall aquifer, southern Michigan
Authors: Ma Lin , Castro Maria Clara , Hall Chris Michael , Walter Lynn M.
Published: October 2005

Helium data and major ion chemistry are presented for the shallow Marshall aquifer in southern Michigan. This data set is subsequently analyzed in conjunction with major element data sets from deeper and shallower water levels previously collected in this area. He excesses and isotopic ratios suggest the presence of tritiogenic 3He in young waters in the Marshall aquifer. He excesses in old groundwater samples are mostly of crustal origin although the presence of a significant mantle He component in some samples cannot be ruled out. He excesses in the Marshall aquifer are unusually high for such shallow depths (≤300 m) and reach over two and three orders of magnitude above those of air‐saturated water (ASW) for 3He and 4He, respectively. He isotopes require a source external to the aquifer, partly supplied by underlying formations within the sedimentary sequence, partly from the crystalline basement. Calibration of He concentrations observed in the Marshall aquifer requires He fluxes of 1 × 10−13 and 1.6 × 10−6 cm3 STP cm−2 yr−1 for 3He and 4He, respectively. These He fluxes are far greater than those reported in other sedimentary basins around the world (e.g., Paris Basin, Gulf Coast Basin) at similar and far greater depths. Such high He fluxes present at such shallow depths within the Michigan Basin strongly suggest the presence of a dominant vertical water flow component and further indicate that impact of recharge water at depth is minor. Upward cross‐formational flow is also likely responsible for the extremely high salinities present in the shallow subsurface of the Michigan Basin. The observed positive correlation between helium and bromide strongly suggests that these two very distinct conservative tracers both originate at greater depths and further suggests that advection is the dominant transport mechanism within the basin. The occurrence of large‐scale cross‐formational flow is also consistent with the evolution displayed by the major ion chemistry throughout most of the sedimentary sequence, indicating that solutes from shallow levels carry the signature of deep formation brines.
Measuring methane emissions from a landfill using a cost‐effective micrometeorological method
Authors: Laurila Tuomas , Tuovinen Juha‐Pekka , Lohila Annalea , Hatakka Juha , Aurela Mika , Thum Tea , Pihlatie Mari , Rinne Janne , Vesala Timo
Published: October 2005

Landfills are one of the largest sources of methane to the atmosphere, yet their emissions are seldom measured. This results in high uncertainties in national emission estimates. We developed a Flame Ionization Detector‐based micrometeorological measurement system and tested it at a large municipal landfill in Finland. The technical characteristics of the system allowed use of the eddy covariance method, enabling emission monitoring at a much lower cost than employing a Tunable Diode Laser instrument, which we used as a reference. Combining methane and carbon dioxide flux measurements we were able to estimate the methane generation rate, gas collection efficiency and oxidation rate in the landfill surface layer. We showed that the oxidation fraction may differ significantly from the default value used in the IPCC emission modelling, and that high emission rates were observed in the active deposition areas of the landfill.
Anthropogenic greenhouse forcing and strong water vapor feedback increase temperature in Europe
Authors: Philipona Rolf , Dürr Bruno , Ohmura Atsumu , Ruckstuhl Christian
Published: October 2005

Europe's temperature increases considerably faster than the northern hemisphere average. Detailed month‐by‐month analyses show temperature and humidity changes for individual months that are similar for all Europe, indicating large‐scale weather patterns uniformly influencing temperature. However, superimposed to these changes a strong west‐east gradient is observed for all months. The gradual temperature and humidity increases from west to east are not related to circulation but must be due to non‐uniform water vapour feedback. Surface radiation measurements in central Europe manifest anthropogenic greenhouse forcing and strong water vapor feedback, enhancing the forcing and temperature rise by about a factor of three. Solar radiation decreases and changing cloud amounts show small net radiative effects. However, high correlation of increasing cloud‐free longwave downward radiation with temperature (r = 0.99) and absolute humidity (r = 0.89), and high correlation between ERA‐40 integrated water vapor and CRU surface temperature changes (r = 0.84), demonstrates greenhouse forcing with strong water vapor feedback.
Conquest by Force: A Narcissistic Reactance Theory of Rape and Sexual Coercion
Authors: Baumeister Roy F. , Catanese Kathleen R. , Wallace Harry M.
Published: October 2005

Men's efforts to force women to engage in unwanted sexual activity can be explained by a combination of reactance theory and narcissism. Reactance theory suggests that deprivation of specific sexual options will cause men to desire them more, to try to reclaim them by forcing sex and by aggressing against the woman who has refused them, and assorted findings support this analysis. Narcissism is proposed to moderate the link, especially because coercion is relatively rare in response to sexual refusals. Evidence about sexually coercive men supports the narcissism hypothesis, such as by showing self-serving cognitive distortions, an excessive concern with being admired, an inflated sense of entitlement, selectively low empathy, and a broadly exploitative approach to heterosexual relations.
The 100 Most Eminent Psychologists of the 20th Century
Authors: Haggbloom Steven J. , Warnick Renee , Warnick Jason E. , Jones Vinessa K. , Yarbrough Gary L. , Russell Tenea M. , Borecky Chris M. , McGahhey Reagan , Powell John L. , Beavers Jamie , Monte Emmanuelle
Published: October 2005

A rank-ordered list was constructed that reports the first 99 of the 100 most eminent psychologists of the 20th century. Eminence was measured by scores on 3 quantitative variables and 3 qualitative variables. The quantitative variables were journal citation frequency, introductory psychology textbook citation frequency, and survey response frequency. The qualitative variables were National Academy of Sciences membership, election as American Psychological Association (APA) president or receipt of the APA Distinguished Scientific Contributions Award, and surname used as an eponym. The qualitative variables were quantified and combined with the other 3 quantitative variables to produce a composite score that was then used to construct a rank-ordered list of the most eminent psychologists of the 20th century.
Moderators of the Emotion Inhibition-Health Relationship: A Review and Research Agenda
Authors: Consedine Nathan S. , Magai Carol , Bonanno George A.
Published: October 2005

The preponderance of a growing literature suggests that emotion inhibition is associated with poorer health. However, although inhibition and health are clearly related, the “inhibition hyhpothesis” has taken on the flavor of a contemporary dogma. Conceptual bases are accepted uncritically, and developments from other domains of psychology are incorporated in a selective, self-supporting, and unenlightening manner. Theories have been tested in homogenous samples, with little attention paid to possible contributions from ethnic diversity, developmental differences, or period effects. This article presents an evolutionary framework within which to consider these phenomena. It critiques the conceptual underpinnings of inhibition-health theories and provides a rationale for the expectation of moderator effects across cultures, individuals, and emotions. Directions for future empirical work are provided.
Clinical Psychology and Evolutionary Psychology: Toward a Dialogue
Authors: Siegert Richard J. , Ward Tony
Published: October 2005

The growth of evolutionary psychology as a theoretical framework for the study of human behavior has been spectacular. However, evolutionary psychology has been largely ignored by clinical psychology. This article is an attempt to encourage greater dialogue between the two. First, some of the major principles of evolutionary psychology are outlined, followed by consideration of some of the criticisms that have been made of this approach. Second, an attempt is made to trace the influence of evolutionary theory on the history and development of clinical psychology. Third, the authors describe how an evolutionary perspective has enhanced the understanding and study of autism and depression. Finally, some implications of an evolutionary perspective for etiological theory, assessment, treatment, and ethics are discussed.
An application of the inverse scattering transform to the modified intermediate long wave equation
Authors: Scoufis George , Cosgrove Christopher M.
Published: October 2005

The modified intermediate long wave (MILW) equation is a (1+1)-dimensional nonlinear singular integro-differential equation that possesses soliton solutions. In an appropriate limit the MILW equation reduces to the well-known modified Korteweg-de Vries equation. In this paper we solve the initial value problem for the MILW equation through a suitable implementation of the inverse scattering transform and use of the Miura-type transformation that maps solutions of the MILW equation into solutions of a complexified version of the standard intermediate long wave (ILW) equation. The initial value used for the MILW equation is assumed to be real valued, sufficiently smooth, and decaying to zero as the absolute value of the spatial variable approaches large values. An interesting feature of the procedure we develop is that soliton solutions for the ILW and MILW equations can be derived by appropriate specializations of a master set of equations.
On the continuous spectral component of the Floquet operator for a periodically kicked quantum system
Authors: McCaw James , McKellar B. H. J.
Published: October 2005

By a straightforward generalization, we extend the work of Combescure [J. Stat. Phys. 59, 679 (1990)] from rank-1 to rank-N perturbations. The requirement for the Floquet operator to be pure point is established and compared to that in Combescure. The result matches that in McCaw and McKeller [J. Math. Phys. 46, 032108 (2005)]. The method here is an alternative to that work. We show that if the condition for the Floquet operator to be pure point is relaxed, then in the case of the δ-kicked Harmonic oscillator, a singularly continuous component of the Floquet operator spectrum exists. We also provide an in-depth discussion of the conjecture presented in the work of Combescure of the case where the unperturbed Hamiltonian is more general. We link the physics conjecture directly to a number-theoretic conjecture of Vinogradov [The Method of Trigonometrical Sums in the Theory of Numbers (Interscience, London, 1954)] and show that a solution of Vinogradov’s conjecture solves the physics conjecture. The result is extended to the rank-N case. The relationship between our work and the work of Bourget [J. Math. Anal. Appl. 276, 28 (2002); 301, 65 (2005)], on the physics conjecture is discussed.
Exceptional N=6 superconformal algebra
Authors: Poletaeva Elena
Published: October 2005

We realize the exceptional N=6 superconformal algebra, spanned by 32 fields, inside the Lie superalgebra of pseudodifferential symbols on the supercircle S1∣3. Correspondingly, we obtain two nonisomorphic one-parameter families of irreducible representations of this superconformal algebra in a superspace spanned by 8 fields.
s
l
2
Gaudin model with jordanian twist
Authors: Cirilo António N. , Manojlović N.
Published: October 2005

s l 2 Gaudin model with jordanian twist is studied. This system can be obtained as the semiclassical limit of the XXX spin chain deformed by the jordanian twist. The appropriate creation operators that yield the Bethe states of the Gaudin model and consequently its spectrum are defined. Their commutation relations with the generators of the corresponding loop algebra as well as with the generating function of integrals of motion are given. The inner products and norms of Bethe states and the relation to the solutions of the Knizhnik-Zamolodchikov equations are discussed.
Breakdown of Lindstedt expansion for chaotic maps
Authors: Gentile Guido , van Erp Titus S.
Published: October 2005

In a previous paper of one of us [Europhys. Lett. 59, 330–336 (2002)] the validity of Greene’s method for determining the critical constant of the standard map (SM) was questioned on the basis of some numerical findings. Here we come back to that analysis and we provide an interpretation of the numerical results, by showing that the conclusions of that paper were wrong as they relied on a plausible but untrue assumption. Hence no contradiction exists with respect to Greene’s method. We show that the previous results, based on the expansion in Lindstedt series, do correspond to the critical constant but for a different map: the semi-standard map (SSM). For such a map no Greene’s method analog is at disposal, so that methods based on Lindstedt series are essentially the only possible ones. Moreover, we study the expansion for two simplified models obtained from the SM and SSM by suppressing the small divisors. We call them the simplified SM and simplified SSM, respectively; the first case turns out to be related to Kepler’s equation after a proper transformation of variables. In both cases we give an analytical solution for the radius of convergence, that represents the singularity in the complex plane closest to the origin. Also here, the radius of convergence of the simplified SM turns out to be lower than that of the simplified SSM. However, despite the absence of small divisors these two radii are lower than those of the true maps (i.e., of the maps with small divisors) when the winding number equals the golden mean. Finally, we study the analyticity domain and, in particular, the critical constant for the two maps without small divisors. The analyticity domain turns out to be a perfect circle for the simplified SSM (as for the SSM itself), while it is stretched along the real axis for the simplified SM, yielding a critical constant which is larger than its radius of convergence.
Quantum trigonometric Calogero-Sutherland model, irreducible characters and Clebsch-Gordan series for the exceptional algebra E7
Authors: Fernández Núñez J. , García Fuertes W. , Perelomov A. M.
Published: October 2005

We reexpress the quantum Calogero-Sutherland model for the Lie algebra E7 and the particular value of the coupling constant κ=1 by using the fundamental irreducible characters of the algebra as dynamical variables. For that, we need to develop a systematic procedure to obtain all the Clebsch-Gordan series required to perform the change of variables. We describe how the resulting quantum Hamiltonian operator can be used to compute more characters and Clebsch-Gordan series for this exceptional algebra.
Basic twist quantization of the exceptional Lie algebra g2
Authors: Borowiec Andrzej , Lukierski Jerzy , Lyakhovsky Vladimir , Mozrzymas Marek , Tolstoy Valeriy N.
Published: October 2005

We present the formulas for twist quantization of g2, corresponding to the solution of a classical YB equation with support in the eight-dimensional Borel subalgebra of g2. The considered chain of twists consists of the four factors describing the four steps of quantization: Jordanian twist, the two twist factors extending Jordanian twist and the deformed Jordanian or in a second variant additional Abelian twist. The first two steps describe as well the sl(3) quantization. The coproducts are calculated for each step in explicit form, and for that purpose we present new formulas for the calculation of similarity transformations on the tensor product. We introduce new basic generators in universal enveloping algebra U(g2) that provide nonlinearities in the algebraic sector maximally simplifying the deformed coproducts.
A theoretical description of the polarization dependence of the sum frequency generation spectroscopy of the water/vapor interface
Authors: Perry Angela , Neipert Christine , Kasprzyk Christina Ridley , Green Tony , Space Brian , Moore Preston B.
Published: October 2005

An improved time correlation function (TCF) description of sum frequency generation (SFG) spectroscopy was developed and applied to theoretically describing the spectroscopy of the ambient water/vapor interface. A more general TCF expression than was published previously is presented—it is valid over the entire vibrational spectrum for both the real and imaginary parts of the signal. Computationally, earlier time correlation function approaches were limited to short correlation times that made signal processing challenging. Here, this limitation is overcome, and well-averaged spectra are presented for the three independent polarization conditions that are possible for electronically nonresonant SFG. The theoretical spectra compare quite favorably in shape and relative magnitude to extant experimental results in the OH stretching region of water for all polarization geometries. The methodological improvements also allow the calculation of intermolecular SFG spectra. While the intermolecular spectrum of bulk water shows relatively little structure, the interfacial spectra (for polarizations that are sensitive to dipole derivatives normal to the interface—SSP and PPP) show a well-defined intermolecular mode at 875cm−1 that is comparable in intensity to the rest of the intermolecular structure, and has an intensity that is approximately one-sixth of the magnitude of the intense free OH stretching peak. Using instantaneous normal mode methods, the resonance is shown to be due to a wagging mode localized on a single water molecule, almost parallel to the interface, with two hydrogens displaced normal to the interface, and the oxygen anchored in the interface. We have also uncovered the origin of another intermolecular mode at 95cm−1 for the SSP and PPP spectra, and at 220cm−1 for the SPS spectra. These resonances are due to hindered translations perpendicular to the interface for the SSP and PPP spectra, and translations parallel to the interface for the SPS spectra. Further, by examining the real and imaginary parts of the SFG signal, several resonances are shown to be due to a single spectroscopic species while the “donor” OH region is shown to consist of three distinct species—consistent with an earlier experimental analysis.
Nanoscale architectures for molecular electronics: Vibrational spectroscopy and structure of solid hexa-n-dodecyl-hexa-peri-hexabenzocoronene
Authors: Carminati Marta , Brambilla Luigi , Zerbi Giuseppe , Muellen Klaus , Wu Jishan
Published: October 2005

The solid columnar discotic and liquid-crystalline phases formed by hexa-n-dodecyl-hexa-peri-hexabenzocoronene (HBC-C12) have been investigated by IR and Raman vibrational spectroscopies. IR spectra clearly show the two phase transitions at 42 and at 107°C already reported in literature and allow us to understand the conformational modifications of the n-alkyl chains that take place through the transitions. Thanks to the collected data, we propose a model of the structure of HBC-C12 in the solid-crystalline phase below 42°C which includes the structure of the alkyl chains. This model is also confirmed by dichroic infrared microscopy measurements on highly oriented samples.
The ns and nd Rydberg states of O2 described by Hund’s case (e)
Authors: Lefebvre-Brion Hélène , Ridley Trevor
Published: October 2005

Using Hund’s case (e) representation, we have obtained a simulation of the 5s Rydberg states of O2 for J=2 by fitting the experimental data obtained recently by Sheard et al. [J. Chem. Phys. 118, 8781 (2003)]. Our analysis permits us to include evidence of not only the mixing of Hund’s case (a) states by spin-orbit interaction, but also by L and S uncouplings. This mixing is even more important for the nd Rydberg states. For the 3d Rydberg state, J=2, we have been able to suggest for the first time an assignment for both the 3dσΠg1 and the 3dδΠg1 states.
Adaptive local refinement of the electron density, one-particle density matrices, and electron orbitals by hierarchical wavelet decomposition
Authors: Pipek János , Nagy Szilvia
Published: October 2005

The common experience that the distribution and interaction of electrons widely vary by scanning over various parts of a molecule is incorporated in the atomic-orbital expansion of wave functions. The application of Gaussian-type atomic orbitals suffers from the poor representation of nuclear cusps, as well as asymptotic regions, whereas Slater-type orbitals lead to unmanageable computational difficulties. In this contribution we show that using the toolkit of wavelet analysis it is possible to find an expansion of the electron density and density operators which is sufficiently precise, but at the same time avoids unnecessary complications at smooth and slightly detailed parts of the system. The basic idea of wavelet analysis is a coarse description of the system on a rough grid and a consecutive application of refinement steps by introducing new basis functions on a finer grid. This step could highly increase the number of required basis functions, however, in this work we apply an adaptive refinement only in those regions of the molecule, where the details of the electron structure require it. A molecule is split into three regions with different detail characteristics. The neighborhood of a nuclear cusp is extremely well represented by a moderately fine wavelet expansion; the domains of the chemical bonds are reproduced at an even coarser resolution level, whereas the asymptotic tails of the electron structure are surprisingly precise already at a grid distance of 0.5a.u. The strict localization property of wavelet functions leads to an especially simple calculation of the electron integrals.
Photochemistry of pyrrole: Time-dependent quantum wave-packet description of the dynamics at the π1σ*-S conical intersections
Authors: Vallet Valérie , Lan Zhenggang , Mahapatra Susanta , Sobolewski Andrzej L. , Domcke Wolfgang
Published: October 2005

The photoinduced hydrogen-elimination reaction in pyrrole via the conical intersections of the two π1σ* excited states with the electronic ground states [B11(πσ*)-S0 and A21(πσ*)-S0] have been investigated by time-dependent quantum wave-packet calculations. Model potential-energy surfaces of reduced dimensionality have been constructed on the basis of accurate multireference ab initio electronic-structure calculations. For the B11-S0 conical intersection, the model includes the NH stretching coordinate as the tuning mode and the hydrogen out-of-plane bending coordinate as the coupling mode. For the A21-S0 conical intersection, the NH stretching coordinate and the screwing coordinate of the ring hydrogens are taken into account. The latter is the dominant coupling mode of this conical intersection. The electronic population-transfer processes at the conical intersections, the branching ratio between the dissociation channels, and their dependence on the initial preparation of the system have been investigated for pyrrole and deuterated pyrrole. It is shown that the excitation of the NH stretching mode strongly enhances the reaction rate, while the excitation of the coupling mode influences the branching ratio of different dissociation channels. The results suggest that laser control of the photodissociation of pyrrole via mode-specific vibrational excitation should be possible. The calculations provide insight into the microscopic details of ultrafast internal-conversion processes in pyrrole via hydrogen-detachment processes, which are aborted at the π1σ*-S0 conical intersections. These mechanisms are of relevance for the photostability of the building blocks of life (e.g., the DNA bases).
Nonadiabatic surface hopping Herman-Kluk semiclassical initial value representation method revisited: Applications to Tully’s three model systems
Authors: Wu Yinghua , Herman Michael F.
Published: October 2005

The nonadiabatic surface hopping Herman-Kluk (HK) semiclassical initial value representation (SC-IVR) method for nonadiabatic problems is reformulated. The method has the same spirit as Tully’s surface hopping technique [J. Chem. Phys. 93, 1061 (1990)] and almost keeps the same structure as the original single-surface HK SC-IVR method except that trajectories can hop to other surfaces according to the hopping probabilities and phases, which can be easily integrated along the paths. The method is based on a rather general nonadiabatic semiclassical surface hopping theory developed by Herman [J. Chem. Phys. 103, 8081 (1995)], which has been shown to be accurate to the first order in ℏ and through all the orders of the nonadiabatic coupling amplitude. Our simulation studies on the three model systems suggested by Tully demonstrate that this method is practical and capable of describing nonadiabatic quantum dynamics for various coupling situations in very good agreement with benchmark calculations.
Resonant Raman spectra and first molecular hyperpolarizabilities of strongly charge-transfer molecules
Authors: Hung S. T. , Wang C. H. , Kelley Anne Myers
Published: October 2005

The effect of vibrational structure on the frequency dependence of the first molecular hyperpolarizability of two thiophene-based charge-transfer chromophores is investigated. A time domain formulation is used to express the polarizability. The new expression includes the solvent-induced inhomogeneous distribution of electronic transition frequencies as well as the effect of the motion of solvent molecules that modulates the vibrational and electronic transition frequencies of the nonlinear optical molecule on which the first molecular hyperpolarizability depends. Resonance Raman scattering and one-photon absorption spectra of the chromophores are measured. By simultaneously fitting the experimental one-photon absorption spectrum and Raman cross sections of vibrational lines derived from resonance Raman scattering to a theoretical model, important parameters needed for the calculation of the first molecular hyperpolarizability are obtained. The first molecular hyperpolarizability is calculated as a function of frequency covering both nonresonance and two-photon resonance regions. The calculated result is compared with the measured hyperpolarizability as a function of frequency of the excitation laser. The resonance Raman-based analysis is shown to account reasonably well for the dispersion of the hyperpolarizability of the two charge transfer chromophores.
Quantum effects in ice Ih
Authors: Hernández de la Peña L. , Gulam Razul M. S. , Kusalik P. G.
Published: October 2005

Quantum and classical simulations are carried out on ice Ih over a range of temperatures utilizing the TIP4P water model. The rigid-body centroid molecular dynamics method employed allows for the investigation of equilibrium and dynamical properties of the quantum system. The impact of quantization on the local structure, as measured by the radial and spatial distribution functions, as well as the energy is presented. The effects of quantization on the lattice vibrations, associated with the molecular translations and librations, are also reported. Comparison of quantum and classical simulation results indicates that shifts in the average potential energy are equivalent to rising the temperature about 80K and are therefore non-negligible. The energy shifts due to quantization and the quantum mechanical uncertainties observed in ice are smaller than the values previously reported for liquid water. Additionally, we carry out a comparative study of melting in our classical and quantum simulations and show that there are significant differences between classical and quantum ice.
Molecular dynamics simulation of self- and mutual diffusion coefficients for confined mixtures
Authors: Zhang Li , Liu Ying-Chun , Wang Qi
Published: October 2005

The self- and mutual diffusion coefficients for binary mixtures of Ar–Kr both in the bulk and in the nanopores were studied by molecular dynamics simulations. The composition dependences and the relationships between the self- and the mutual diffusion coefficients both in the bulk and in the nanopores were further discussed. It was found that the simulation results (Dc.m.) are close to the calculated ones (Ds) for the Ar–Kr system. Both self- and mutual diffusion coefficients in nanopores are much lower than that of the bulk, and they ever decrease as the pore width decreases. Nevertheless, the self- and mutual diffusion coefficients increase as the mole fraction of Ar increases, and as expected, increase as the temperature increases. The self-diffusion coefficients of mixtures both in the bulk and in the nanopores are predicted by the Carman model and by the molecular cluster model.
Indentation of rigid cones into conical holes molded in elastic blocks
Authors: Lim Yong Yee , Chaudhri M. Munawar
Published: October 2005

Results obtained from several series of experiments on the normal loading of rigid spherical and conical indenters onto elastic blocks are described. Different series of experiments conducted are (1) normal loading of a rigid sphere onto elastic blocks of polydimethylsiloxane of different elastic moduli, (2) normal loading of rigid cones of different included angles onto a flat of the elastic blocks, and (3) normal loading of rigid cones of different included angles into conical holes of various included angles molded in the two types of elastic block. It was found that the indenter load versus indenter displacement data corresponding to the normal loading of the sphere and cones of different included angles onto a flat surface of the elastic blocks were very well fitted by the theories of Hertz and Sneddon, respectively. It has also been found that when rigid cones were loaded into conical holes molded in the elastic blocks, the load versus indenter displacement data were not fitted by the Sneddon theory for a conical indenter loading onto an elastic half space. Neither were the experimental data fitted by a modified Sneddon equation in which the effective semi included angle β of the conical indenter was taken as β=[(π∕2)−(α′−α)], with α′ and α being the semi-included angles of the conical hole and the indenter, respectively. These results cast some doubt on the validity of some of the current methods in use for analyzing the unloading curves obtained from nanoindentation experiments made using pointed pyramidal and conical indenters on elastic-plastic solids.
Nanostructures and self-catalyzed growth of SnO2
Authors: Wang B. , Yang Y. H. , Wang C. X. , Yang G. W.
Published: October 2005

SnO 2 nanostructures including one-dimensional nanowires and two-dimensional nanobelts have been grown on a gold covered single crystal silicon substrates using thermal evaporation of active carbon and SnO2 powders. Field emission scanning electron microscopy, x-ray diffraction, Raman spectra, and high-resolution transmission electron microscopy are used to identify the morphology and the structure of these resulting SnO2 nanostructures. Based on these experimental analyses, we found self-catalyzed growth of SnO2 nanocrystals on top of SnO2 nanowires, i.e., SnO2 can spontaneously nucleate on the (110) crystalline plane of SnO2 nanowires without any catalyst. The growth behavior of these synthesized SnO2 nanostructures is discussed on the basis of the vapor-liquid-solid mechanism.
Influence of growth temperature on minority-carrier lifetime of Si layer grown by liquid phase epitaxy using Ga solvent
Authors: Satoh Yusuke , Usami Noritaka , Pan Wugen , Fujiwara Kozo , Nakajima Kazuo , Ujihara Toru
Published: October 2005

The influence of growth temperature on the minority-carrier lifetime of epitaxial Si layers was systematically investigated. Epitaxial Si layers were grown on (111) Si substrates in the temperature range of 500–900°C by liquid phase epitaxy using Ga solvent. To ensure that the contribution of the annealed Si substrate during growth will be excluded, the overall lifetime of the epitaxial layer and the Si substrate was measured as a function of the thickness of the substrate. This procedure revealed that the minority-carrier lifetime of the epitaxial Si layers increases upon lowering the growth temperature. This can be explained by the lower impurity concentration as measured by secondary-ion mass spectroscopy. Moreover, the existence of a slightly misoriented crystal domain was found in the Si layer grown at a high temperature. These results suggest that low growth temperature should be employed in growing a Si film with high minority-carrier lifetime.
Phase diagram of softly repulsive systems: The Gaussian and inverse-power-law potentials
Authors: Prestipino Santi , Saija Franz , Giaquinta Paolo V.
Published: October 2005

We redraw, using state-of-the-art methods for free-energy calculations, the phase diagrams of two reference models for the liquid state: the Gaussian and inverse-power-law repulsive potentials. Notwithstanding the different behaviors of the two potentials for vanishing interparticle distances, their thermodynamic properties are similar in a range of densities and temperatures, being ruled by the competition between the body-centered-cubic (bcc) and face-centered-cubic (fcc) crystalline structures and the fluid phase. We confirm the existence of a reentrant bcc phase in the phase diagram of the Gaussian-core model, just above the triple point. We also trace the bcc-fcc coexistence line of the inverse-power-law model as a function of the power exponent n and relate the common features in the phase diagrams of such systems to the softness degree of the interaction.
Generation of multi-keV monochromatic twin x-ray point sources based on laser-driven vacuum diode
Authors: Moorti A. , Naik P. A. , Gupta P. D.
Published: October 2005

A simple method of generating multi-keV, monochromatic, twin x-ray point sources based on laser-driven vacuum diode is presented. Electrons from a laser-produced aluminum plasma cathode were accelerated towards two point-tip titanium anodes placed symmetrically with respect to the cathode. Temporal and spatial characterizations of the K-shell x-ray emission from the twin anodes are carried out. Each source (∼300μm diameter) emits ∼109TiKα (hν≈4.51keV) photons in a pulse of ∼20ns duration with a peak brightness of ∼4×1018photons∕cm2ssr. Single-shot twin x-ray shadowgrams of physical objects were recorded at a distance of several centimeters from the two sources. Such a system may be useful for single-shot stereoradiography for differential imaging in the multi-keV energy region.
Modeling and design of an optimized liquid-crystal optical phased array
Authors: Wang Xinghua , Wang Bin , Bos Philip J. , McManamon Paul F. , Pouch John J. , Miranda Felix A. , Anderson James E.
Published: October 2005

In this paper, the physics that determines the performance limits of a diffractive optical element based on a liquid-crystal (LC) optical phased array (OPA) is investigated by numerical modeling. The influence of the fringing electric fields, the LC material properties, and the voltage optimization process is discussed. General design issues related to the LC OPA configuration, the diffraction angle, and the diffraction efficiency are discussed. A design for a wide-angle LC OPA is proposed for high-efficiency laser beam steering. This work provides fundamental understanding for a light beam deflected by a diffractive liquid-crystal device.
Residual stresses of diamond and diamondlike carbon films
Authors: Liu E. , Li L. , Blanpain B. , Celis J. P.
Published: October 2005

This paper evaluated the internal stresses of different diamond and diamondlike carbon (DLC) coatings. For the diamond coatings, the stresses were determined using micro-Raman spectroscopy and x-ray diffraction (XRD), while the stresses of DLC films were determined with bent plate method. The internal stress was related to the structural properties of the coatings. Direct current plasma jet, combustion flame, and microwave chemical-vapor deposition processes were used to prepare the diamond coatings on the tungsten carbide or molybdenum substrates, while the DLC films were deposited on the silicon wafers with filtered cathodic vacuum arc process. From the Raman spectra of the diamond coatings, the compressive internal stresses were determined, which were related to the microstructure of the coatings. The results from XRD were comparable with those obtained from micro-Raman spectroscopy. Higher compressive residual stresses in the DLC films were noticed, which were also related to their chemical bonding nature as well as their microstructures.
Dichroic reflection of InAs∕GaAs quantum dots
Authors: Bogaart E. W. , Haverkort J. E. M. , Eijkemans T. J. , Mano T. , Nötzel R. , Wolter J. H.
Published: October 2005

Polarization-resolved reflection measurements are performed on nearly circular InAs∕GaAs quantum dots (QDs) by means of time-resolved differential reflection spectroscopy. We observe linear polarization anisotropy of the differential absorption, revealing the dichroic character of the QD reflection. The observed magnitude of the dichroism is Θ[11¯0]∕Θ[110]=1.07. The polarization has a preferential direction orientated along the [11¯0] crystal axis, which is confirmed by polarization-resolved photoluminescence. We observe that the polarization anisotropy of the reflectivity is strongly dependent on the pump excitation density, decreasing from ρ=0.14 at low excitation to ρ=0.06 at high excitation. The pump power dependence is described by a binomial model taking into account the statistics of carrier capture into a limited number of QDs.
Ge
∕
Si
islands in a three-dimensional island crystal studied by x-ray diffraction
Authors: Novák J. , Holý V. , Stangl J. , Fromherz T. , Zhong Zhenyang , Chen Gang , Bauer G. , Struth B.
Published: October 2005

Coplanar high-resolution x-ray diffraction has been used for the characterization of size, chemical composition, and strain of Ge∕Si (001) islands in a three-dimensional island crystal grown using self-assembly on a prepatterned (001) Si substrate. The measured diffusely scattered intensity is simulated using the kinematical approximation and the parameters of model islands are fitted. These simulations require calculations of the strain fields within the islands and the spacer layers. For this purpose, an analytical approach to solve the continuum elasticity equations has been extended to a full three-dimensional calculation. The Ge content in the islands is found to be on the average 40%, and the island shape does not change dramatically during capping.
Characterization of nanostructure in Si1−xGex epilayers using x-ray reflectivity and fluorescence techniques
Authors: Kim S. , Kioseoglou G. , Huang S. , Kao Y. H. , Soo Y. L. , Zhu X. , Wang K. L.
Published: October 2005

X-ray reflectivity and angular dependence of x-ray fluorescence (ADXRF) techniques are used for nondestructive characterization of nanostructure and interface morphology in a series of Si1−xGex epilayers grown on Si by molecular-beam epitaxy. The ADXRF method is element specific, well suited for probing the depth profile of Ge in the system without disturbing the integrity of the material structure under study. The layer thickness, interfacial roughness, Ge concentration, lattice parameters, and x-ray optical constants for the entire series have been determined. The results show that the Si1−xGex epilayers with x values between 0.27 and 0.83 are neither completely pseudomorphic nor fully relaxed. We have thus demonstrated that the reflectivity and ADXRF methods can be used as effective tools for studying various types of nanostructure in alloys.