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Using surface x-ray diffraction and scanning tunneling microscopy in combination with first-principles calculations, we have studied the geometric and electronic structure of Cs-deposited Bi2Se3(0001) surface kept at room temperature. Two samples were investigated: a single Bi2Se3 crystal, whose surface was Ar sputtered and then annealed at ∼500 ◦C for several minutes prior to Cs deposition, and a 13-nm-thick epitaxial Bi2Se3 film that was not subject to sputtering and was annealed only at ∼350 ◦C. In the first case, a considerable fraction of Cs atoms occupy top layer Se atoms sites both on the terraces and along the upper step edges where they form one-dimensional-like structures parallel to the step. In the second case, Cs atoms occupy the f cc hollow site positions. First-principles calculations reveal that Cs atoms prefer to occupy Se positions on the Bi2Se3(0001) surface only if vacancies are present, which might be created during the crystal growth or during the surface preparation process. Otherwise, Cs atoms prefer to be located in f cc hollow sites in agreement with the experimental finding for the MBE-grown sample., We acknowledge financial support from DFG through priority program SPP1666 (Topological Insulators), as well as by the University of the Basque Country (Grant Nos. GIC07IT36607 and IT-756-13), the Spanish Ministry of Science and Innovation (Grant Nos. FIS2013-48286-C02-02-P, FIS2013-48286-C02-01-P, and FIS2016-75862-P) and Tomsk State University Academic D.I. Mendeleev Fund Program in 2015 (research Grant No. 8.1.05.2015). Partial support by the Saint Petersburg State University project No. 15.61.202.2015 is also acknowledged. The study has also been supported by the Russian Science Foundation (project No. 17-12-01047) in part of the single crystal growth and structural characterization. Technical support by F. Weiss is gratefully acknowledged.

Mass selective deposition of C7H3(+) (m/z = 87) into solid neon reveals the 1(1)A1←X(1)A1 electronic absorption system of hepta-1,2,3,4,5,6-heptahexaenylium cation B(+) [H2CCCCCCCH](+) with an origin band at 441.3 nm, 1(1)A'←X(1)A' transition of 2,4-pentadiynylium,1-ethynyl cation C(+) [HCCCHCCCCH](+) starting at 414.6 nm and the 1(1)A1←X(1)A1 one of cyclopropenylium,1,3-butadiynyl cation A(+) [HCCCCC(CH=CH)](+) with an onset at 322.2 nm. Vibrationally resolved fluorescence was observed for isomer B(+) upon laser excitation of the absorption bands in the 1(1)A1←X(1)A1 transition. After neutralization of the cations in the matrix five absorption systems of the C7H3 neutral radicals starting at 530.3, 479.4, 482.3, 325.0 and 302.5 nm were detected. These were identified as the 1(2)A'←X(2)A' and 2(2)A'←X(2)A' electronic transitions of 2-(buta-1,3-diynyl)cycloprop-2yl-1-1ylidene E˙ [HCCCCC(C=CH2)]˙, 1(2)B1←X(2)B1 of 1,2,3,4,5,6-heptahexaenyl B˙ [H2CCCCCCCH]˙, 3(2)B1←X(2)B1 of 3-buta-1,3-diynyl-cyclopropenyl A˙ [HCCCCC(CH=CH)]˙ and 2(2)B1←X(2)A2 transition of 1,2-divinylidene-cyclopropanyl radical F˙ [HCC-cyc-(CCHC)-CCH]˙, respectively. The assignment is based on calculated vertical excitation energies using the CASPT2 method. Comparison of the calculated harmonic vibrational frequencies with those inferred from the spectra supports the assignment.

Multiple Sclerosis (MS) involves an immune mediated process in which an abnormal response of the body’s immune system is directed against the central nervous system (CNS). Multiple sclerosis is a very variable condition and the symptoms depend on which areas of the CNS have been affected. There is no set pattern for MS and everyone with MS has a different set of symptoms, which vary from time to time and can change in severity and duration, even in the same person. Hence diagnosing MS at the earliest is very essential. Therefore we report an unusual case of a 30-year-old female with complaints of headache, vomiting & hiccups since 2 months followed by weakness of bilateral lower limbs and later upper limbs which eventually were diagnosed as Multiple Sclerosis. We are reporting this case because of the vague clinical presentation of Multiple Sclerosis. Aim: To recognize the symptoms of MS at the earliest and start treatment early.

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Electronic absorption spectra of C7O, neutral and cationic, have been obtained after mass selection and deposition into 6 K neon matrices. The band system with origin at 305.1 nm is identified as the (2) 1Σ+ ← X 1Σ+ electronic transition of linear C7O, and the absorption, with onset at 276.0 nm, to (4) 2Σ+ ← X 2Σ+ of C7O+ on the basis of experimental observations and theoretical calculations.

The fragment ions C6HF+ and C6F 2 + produced from fluorobenzenes in a discharge source were trapped in 6 K neon matrices after mass selection. A strong absorption system is detected in the visible range starting at 586.3 nm for C6HF + and 569.3 nm for C6F2 +. Vibrationally resolved fluorescence commencing at the same wavelengths is observed upon laser excitation into each absorption band of these cations. The absorptions are assigned to the A2?g ? X 2?u and A2? ? X2? transitions of linear FC6F+ and HC6F + respectively. The assignment is based on the similarity of the absorption and fluorescence spectra with the A2?g ? X2?u electronic system of linear HC 6H+ as well as the theoretically calculated vibrational and electronic excitation energies of the FC6F+ and HC6F+. © 2013 Elsevier B.V. All rights reserved.

In this Perspective the development and application of a mass selective matrix isolation approach employed with success over the last two decades in the spectroscopic characterization of numerous ions and neutral reactive species is illustrated with original data for hydrocarbon cations and neutrals with a six and a five membered carbon ring fused. The setup allows for the electronic and vibrational assessment of these isolated molecules and ions in the inert neon environment. The transient species of interest are chosen due to their astrophysical relevance and the role they play in flames plasmas combustion organic reactions and atmospheric chemistry. Electronic absorption and fluorescence spectra of indene related polycyclic aromatic hydrocarbon derivatives C9Hy + (y = 7 9) cations are presented. The ions were produced in a discharge source and investigated by means of absorption and emission spectroscopies after selectively trapping them in 6 K neon matrices. Photoconversion between the two C9H 8 + indenylium isomers and upon irradiation H2 loss from C9H9 + were observed. Corresponding neutral species C9Hy are identified by photobleaching the matrices containing the cations. © 2013 the Owner Societies.

The dependence of hysteretic properties of FeMn/CoFeB (AF/FM) thin bilayers on AF thickness and magnetic annealing temperature is systematically investigated for possible applications in spin-valve devices. Inducement of an easy axis after magnetic annealing is established. The anisotropy is studied by investigating the coercivity along and perpendicular to the induced easy axis using Magneto-Optic Kerr Effect (MOKE) and the AF texture is ascertained by XRD. The existence of an optimum annealing temperature, for which the maximum change in coercivity occurs for a particular AF thickness, is evidenced. The maxima in HC of the bilayer with thickness of AF layer were correlated with FCC FeMn (111) texture of the sample.

Two electronic transitions at 512.3 and 250 nm of linear-C5H(+) are detected following mass-selective deposition of m/z = 61 cations into a 6 K neon matrix and assigned to the 1 (1)Π←X (1)Σ(+) and 1 (1)Σ(+)←X (1)Σ(+) systems. Five absorption systems of l-C5H with origin bands at 528,7, 482.6, 429.0, 368.5, and 326.8 nm are observed after neutralization of the cations in the matrix and identified as transitions from the X (2)Π to 1 (2)Δ, 1 (2)Σ (-), 1 (2)Σ(+), 2 (2)Π, and 3 (2)Π electronic states. The assignment to specific structures is based on calculated excitation energies, vibrational frequencies in the electronic states, along with simulated Franck-Condon profiles.

We present and interpret the observations of extreme ultraviolet (EUV) waves associated with a filament eruption on 2011 May 11.The filament eruption also produces a small B-class two ribbon flare and a coronal mass ejection (CME). The event is observed by the Solar Dynamic Observatory (SDO) with high spatio-temporal resolution data recorded by Atmospheric Imaging Assembly (AIA). As the filament erupts, we observe two types of EUV waves (slow and fast) propagating outwards. The faster EUV wave has a propagation velocity of ~ 500 km/s and the slower EUV wave has an initial velocity of ~ 120 km/s. We report for the first time that not only the slower EUV wave stops at a magnetic separatrix to form bright stationary fronts, but also the faster EUV wave transits a magnetic separatrix, leaving another stationary EUV front behind., 24 pages, 6 Figures, accepted for the publication in Astrophysical Journal

C7H4O2+ and C7H5O2+ ions and the respective neutrals have been investigated by absorption spectroscopy in neon matrixes following mass selection of ions produced from salicylic acid. Three electronic transitions starting at 649.6, 431.0, and 372.0 nm are detected for C7H4O2+ and assigned on the basis of CASPT2 energies and Franck–Condon simulations as the excitations from the X 2A″ to the 1 2A″, 2 2A″, and 3 2A″ electronic states of 6-(oxomethylene)-2,4-cyclohexadien-1-one ion (A+). Absorptions commencing at 366.4 nm are observed for C7H5O2+ and assigned to the 1 2A′ ← X 2A′ electronic transition of (2-hydroxyphenyl)methanone ion (J+). Neutralization of J+ leads to the appearance of four absorption systems attributed to the 4 2A″, 3 2A″, 2 2A″, and 1 2A″ ← X 2A″ transitions of J with origin bands 291.3, 361.2, 393.8, and 461.2 nm.

The Chicago Cultural Alliance (CCA) is a unique consortium, uniting 29 community-based ethnic museums, cultural centers, and historical societies with 18 mainstream cultural institutions. CCA's mission is to effect positive social change and public understanding of cultural diversity through the first-voice perspectives of its members. It provides a new model for collaboration that values the assets of ethnic organizations as equal to the professional expertise of mainstream institutions and harnesses these collective assets to deliver programs that meet both sets of organizations' needs. Through its civic dialogue program ( Talking About...) CCA provides a template for members to collaborate on cross-cultural programs which explore the intersection of contemporary civic issues with cultural heritage. Using Talking About... as an example, we examine CCA's Civic Engagement Model, specifically addressing efforts to build members' capacity to engage with issues of contemporary significance and includ...

Fluorescence spectra of protonated pyrene and coronene in solid neon have been observed. Laser excitation of the Sn ← S0 transitions of the cations results in an extended, vibrationally-resolved S1 → S0 fluorescence with onset at 487.8 and 695.4 nm for protonated pyrene and coronene, respectively. Vibrational assignment of the spectra has been made on the basis of the calculated frequencies of normal modes in the ground electronic state. The astrophysical relevance of the frequencies inferred for these protonated cations is discussed.

The structural and magnetic properties of as-grown 5–50 nm thin ion-beam sputter deposited transition metal–metalloid Co 20 Fe 60 B 20 (CFB) films are reported in this communication. A broad peak observed at 2 θ ∼45° in the glancing angle X-ray diffraction pattern revealed the formation of very fine nano-sized grains embedded in majority amorphous CFB matrix. Although no magnetic field is applied during deposition, the longitudinal magneto-optic Kerr effect measurements performed at 300 K in these as-grown films clearly established the presence of in-plane uniaxial magnetic anisotropy ( K u ). It is argued that this observed anisotropy is strain-induced. This is supported by the observed dependence of direction of K u on the angle between applied magnetic field and crystallographic orientation of the underlying Si(100) substrate, and increase in the coercivity with the increase of the film thickness.

Polybrominated diphenyl ethers (PBDEs) are a group of persistent organic pollutants. They are used as flame retardants in plastics, paints, varnishes and textile materials. PBDEs pose great risk to the environment because of their high persistence and ability to get into the environment easily due to the lack of chemical bonds with the matrix of materials, to which they are added. Global research studies confirmed the occurrence of those compounds in the majority of elements of water and land environment. Analysis of PBDEs in environmental samples is one of the specific analytical methods of criteria that comprise low detection limits and high selectivity. The analysis of PBDEs in environmental samples is one of the specific analytical methods, in which the main criteria are low detection limits and high selectivity. In this article, a literature review of methods for environmental sample preparation and analysis of the PBDE content was presented. The article discusses the potential of modern extraction techniques such as: solid-phase microextraction, single-drop microextraction, dispersive liquid-liquid microextraction, microwave-assisted extraction, cloud point extraction, hollow fibre-liquid phase microextraction and others for the separation of PBDEs from environmental samples with a complex matrix. Among the methods for qualitative and quantitative determination of PBDEs, a particular focus was put on gas chromatography/mass spectrometry with various injection techniques and different types of sample ionisation.

Two experimental methods were applied to identify the structure and electronic transitions of C4H3Cl+ isomers. The first is a direct absorption technique where mass-selected ions are embedded in 6 K neon matrices using a mass-selected ion beam and absorption spectra of different C4H3Cl+ isomers were thus observed. The second is a gas phase method on ions which have been collisional cooled with cryogenic helium inside of a 22-pole ion trap. The c-type (1)2 A′ ← X 2 A″ electronic transition of a C4H3Cl+ isomer could then be measured by a one-colour, two-photon technique at 20 and 50 K in the gas phase. The two sets of data, complemented by calculated excitation energies, allowed the assignment of particular isomers. Rotational structure in the gas phase spectra was resolved for C4H3 35Cl+ and C4H3 37Cl+ isomers of cis-1-chlorobutenynylium. The analysis leads to the spectroscopic constants: T 00 = 19 184.680(5), , , , , and (all in cm−1).

/CoFe/IrMn/CoFeB trilayers without any “eld cooling protocol. Theappearance of positive exchange bias is attributed to the antiferromagnetic coupling between theuncompensated Mn and ferromagnetic (FM) CoFeB spins at the interface. PEB in our sample isobtained as a consequence of interfacial microstructure control leading to unidirectional exchangeanisotropy, brought about by the incident energetic atoms/ions produced during ion-beam sputter-ing. On magnetic annealing, enhancement in the coercivity and disappearance of exchange bias isobserved irrespective of IrMn (111) textured growth due to the irreversible changes in the interfacialspin structure. The coercivity of CoFeB layers can be tuned by varying the seed layer thickness inthe magnetically annealed samples. The signi“cance of this work is a new insight into the effectof incident energetic atomic ”ux on the interfacial microstructure leading to positive exchange bias.Moreover, this study is promising in paving way for the utilization of trilayer stack with independentlyswitchable FM layers in CoFeB based TMR and GMR structures.

Amyloid fibrils, which are often associated with certain degenerative disorders, reveal a number of intriguing spectral properties. However, the relationship between the structure of fibrils and their optical traits remains poorly understood. Poly(L-glutamic) acid is a model polypeptide shown recently to form amyloid-like fibrils with an atypical infrared amide I' band at 1595 cm(-1), which has been attributed to the presence of bifurcated hydrogen bonds coupling C═O and N-D groups of the main chains to glutamate side chains. Here we show that this unusual amide I' band is observed only for fibrils grown from pure enantiomers of the polypeptide, whereas fibrils precipitating from equimolar mixtures of poly(L-glutamic) and poly(D-glutamic) acids have amide I' bands at 1684 and 1612 cm(-1), which are indicative of a typical intermolecular antiparallel β-sheet. Pure enantiomers of polyglutamic acid form spirally twisted superstructures whose handedness is correlated to the amino acid chirality, while fibrils prepared from the racemate do not form scanning electron microscopy (SEM)-detectable mesoscopically ordered structures. Vibrational circular dichroism (VCD) spectra of β-aggregates prepared from mixtures of all L- or D-polyglutamic acid in varying ratios indicate that the enhancement of VCD intensity correlates with the presence of the twisted superstructures. Our results demonstrate that both IR absorption and enhanced VCD are sensitive to subtle packing defects taking place within the compact structure of amyloid fibrils.

Benzyl and tropyl in charge: Electronic spectra of mass-selected benzylium (Bz+) and tropylium (Tr+) cations embedded in solid neon are reported for the first time. They reveal a weak (1)1B1←equation image1A1 visible (see picture) and a much stronger (1)1A1←equation image1A1 ultraviolet transition for Bz+ (C2v symmetry). The lowest dipole-allowed 1A′′2←equation image1A′1 absorption in the ultraviolet region for Tr+ (D7h) is also observed.

Electronic transitions of protonated benzene (Ã (1)B(2)←X̃ (1)A(1), origin at 325 nm) and α-protonated fulvene (Ã (1)A'←X̃ (1)A', at 335 nm) trapped in 6 K neon matrices have been detected. The cations were produced from several different precursors, mass-selected, and co-deposited with neon. After neutralization of the cations, the electronic transitions of cyclohexadienyl (onsets at 549 and 310 nm) and α-hydrogenated fulvene (532 and 326 nm) radicals were identified. Upon excitation of cyclohexadienyl to the B̃ (2)B(1) state, photoisomerization to an open-chain structure and α-hydrogenated fulvene was observed.

The sulfur S n - n = 2, 3 anions produced in a hot cathode discharge ion source were mass-selected and embedded in a neon matrix at 6 K. A long progression with the excitation of up to 12 vibrational quanta is observed in the A 2Πu ← X 2Πg electronic spectrum of S 2 - , with the onset at 467.1 nm. The inferred spectroscopic constants in the A 2Πu state are: ν0−0 = 21,407 ± 4 cm−1, ω 0 ′ = 328.4 ± 1 cm−1, ω 0 ′ x 0 ′ = 2.4 ± 0.1 cm−1. The electronic spectrum of S 3 - in a neon matrix exhibits a rich vibrational structure with a bimodal intensity distribution. This results from the overlap of two electronic transitions, C ∼ 2 A 2 ← X ∼ 2 B 1 and ( D ∼ or E ∼ ) ← X ∼ 2 B 1 , with origins at 701.3 and 619.1 nm. The frequencies (cm−1) of the totally symmetric modes ν1 and ν2 are 466, 184 in the C ∼ 2 A 2 and 446, 177 in the ( D ∼ or E ∼ ) states.

The polyacetylene HC2nH+ n = 2-7 cations were produced from a mixture of diacetylene with helium in a hot cathode-discharge source. After a mass-selective deposition, their absorption spectra were studied in 6 K neon matrixes. Besides the known A2Pi-- X2Pi system, several new transitions to higher excited 2Pi electronic states of these cations have been observed. In the case of HC4H+ and HC6H+, only one new weak absorption system has been detected with the onset at 336.1 and 417.2 nm, respectively. These C2Pi-- X2Pi transitions form a series that extends to HC10H+. Two further electronic transitions are observed for HC8H+ through to HC14H+; a weaker B2Piu-- X2Pig and a strong E2Piu-- X2Pig in the UV. The integrated intensity of the UV system of the polyacetylene cations exceeds that of the A2Pi-- X2Pi transition by an order of magnitude.

The fulvenallenyl radical was produced in 6 K neon matrices after mass-selective deposition of C7H5(-) and C7H5(+) generated from organic precursors in a hot cathode ion source. Absorption bands commencing at λ=401.3 nm were detected as a result of photodetachment of electrons from the deposited C7H5(-) and also by neutralization of C7H5(+) in the matrix. The absorption system is assigned to the 1 (2)B1 ←X (2)B1 transition of the fulvenallenyl radical on the basis of electronic excitation energies calculated with the MS-CASPT2 method. The vibrational excitation bands detected in the spectrum concur with the structure of the fulvenallenyl radical. Employing DFT calculations, it is found that the fulvenallenyl anion and its radical are the global minima on the potential energy surface among plausible structures of C7H5.

The $1 ^3\Sigma_u^- \leftarrow X^3\Sigma_g^-$ transition of linear HC$_5$H (A) has been observed in a neon matrix and gas phase. The assignment is based on mass-selective experiments, extrapolation of previous results of the longer HC$_{2n+1}$H homologues, and density functional and multi-state CASPT2 theoretical methods. Another band system starting at 303 nm in neon is assigned as the $1 ^1 A_1 \leftarrow X ^1 A_1$ transition of the cumulene carbene pentatetraenylidene H$_2$C$_5$ (B)., Comment: 7 pages, 4 figures, 5 tables