Generation of atomic Greenberger-Horne-Zeilinger states and cluster states through cavity-assisted interaction

This paper proposes a scalable scheme to generate n-atom GHZ states and cluster states by using the basic building block, i.e., a weak coherent optical pulse [α） being reflected successively from a single-atom cavity. In the schemes, coherent state of light is used instead of single photon source, homodyne measurement on coherent light is done kastead of single photon detection, and no need for individually addressing keeps the schemes easy to implement from the experimental point of view. The successful probabilities of our protocols approach unity in the ideal case.     

Raman spectroscopic and SEM analysis of sodium‐zippeite

Raman at 298 and 77 K and infrared spectra of two samples of sodium‐zippeite were studied and interpreted. U O bond lengths in uranyl were calculated and compared with those inferred from the X‐ray single crystal structure data of a synthetic sodium‐zippeite analogue. Hydrogen‐bonding network in the studied samples is discussed. O H…O bond lengths were calculated and compared with those predicted from the X‐ray single crystal structure analysis. Copyright © 2007 John Wiley & Sons, Ltd.     

Raman and surface‐enhanced Raman spectroscopic studies of the 15‐mer DNA thrombin‐binding aptamer

Aptamers are single‐stranded oligonucleotides that selectively bind to their target molecules owing to their ability to form secondary structures and shapes. The 15‐mer (5′‐GGTTGGTGTGGTTGG‐3′) DNA thrombin‐binding aptamer (TBA) binds to thrombin following the formation of a quadruplex structure via the Hoogsten‐type G–G interactions. In the present study, Raman and SERS spectra of TBA and thiolated TBA (used to facilitate covalent bonding to metal nanoparticle) in different conditions are investigated. The spectra of the two analogs exhibit vibrations, such as the C8N7 H2 deformation band at ∼1480 cm⁻¹ of the guanine tetrad, that are characteristic of the quadruplex structure in the presence of K⁺ ions or at low temperature. Interestingly, SERS spectra of the two analogs differ markedly from their respective normal Raman spectra, possibly due to changes in the conformation of the aptamer upon binding, as well as to the specific interaction of individual vibrational modes with the metal surface. In addition, the SERS spectra of the thiolated aptamer show significant changes with different concentrations, which may be due to different orientation of the molecule with respect to the metal surface. This study provides useful information for the development of label‐free aptamer‐based SERS sensors and assays. Copyright © 2009 John Wiley & Sons, Ltd.     

Resonance Raman spectroscopic and density functional theory investigation of the excited state structural dynamics of 2‐mercapto‐1‐methylimidazole

The resonance Raman spectroscopy in conjunction with the density functional theory calculations were used to study the excited state structural dynamics of 2‐mercapto‐1‐methylimidazole (MMI). The experimental UV absorption bands were assigned according to the time‐dependent density functional calculations. The vibrational assignments were done for the A‐band resonance Raman spectra of MMI in water and acetonitrile on the basis of the Fourier transform infrared (FT‐IR) and FT‐Raman measurements in solid, in water and in acetonitrile and the corresponding B3LYP/6‐311+G(d, p) computations. The dynamic structures of MMI were obtained by analysis of the resonance Raman intensity pattern and normal mode analysis. The differences in the dynamic structures of MMI and thiourea were revealed and explained. The structural dynamic of MMI was found to be similar to that of 2‐thiopyrimidone in terms of major reaction coordinates and thus favored the intra‐molecular proton transfer reaction. Copyright © 2012 John Wiley & Sons, Ltd.     

A theoretical scheme for generation of Gazeau-Klauder coherent states via intensity-dependent degenerate Raman interaction

A theoretical scheme is presented for generating Gazeau-Klauder coherent states (GKCSs) via the generalization of degenerate Raman interaction with coupling constant to intensity dependent coupling. Firstly, we prove that in the intensity dependent degenerate Raman interaction, under particular conditions, the modified effective Hamiltonian can be used instead of Hamiltonian in the interaction picture, for describing the atom-field interaction. We suppose that the cavity field is initially prepared in a nonlinear CS, which is not temporally stable. As we will observe, after the occurrence of the interaction between atom and field, the generated state involves a superposition of GKCSs which are temporally stable and initial nonlinear CS. Under specific conditions which may be prepared, the generated state just includes GKCS. So, in this way we produced the GKCS, successfully.     

Infrared and Raman spectroscopic studies of L‐valinium picrate

The vibrational assignments of the observed wavenumbers have been made by analyzing the infrared and Raman spectra of L ‐valinium picrate in the crystalline state at room temperature. L ‐Valinium acts as the cation of the crystal and the carbonyl CO group exists in the protonated form in it. Asymmetric deformation and symmetric deformation modes of the isopropyl group have been identified, indicating that the two CH₃ groups are in different environments. The stretching and bending modes of the various functional groups have been shifted owing to the extensive intermolecular hydrogen bonding in the crystal. The symmetry of the picrate anion has not been modified in the crystal by the hydrogen bonding with the cation. Fermi resonance is also observed. Copyright © 2006 John Wiley & Sons, Ltd.     

Raman spectroscopic investigation of lanthana‐doped neodymium‐yttria transparent ceramics

Transparent ceramics of the formula (Nd_0.01La_xY_0.99−x)₂O₃ (x = 0, 0.05, 0.10) were made with nanopowders and sintered in H₂ atmosphere. The Raman spectra of Ln₂O₃ (Ln = Y, La, Nd) powders and (Nd_0.01La_xY_0.99−x)₂O₃ ceramics were investigated. The results show that both La₂O₃ and Nd₂O₃ powders are of hexagonal structure, and all (Nd_0.01La_xY_0.99−x)₂O₃ ceramics exhibit the same cubic Y₂O₃ crystal structure. Their lattice parameters were refined by the Rietveld method. The full‐widths at half‐maximum of Raman peaks increase with the increase in La₂O₃ content in transparent (Nd_0.01Y_0.99)₂O₃ ceramics, while their intensities decrease. At the same time, All Raman peaks shift to lower wavenumbers, and the phonon energy is slightly reduced. Copyright © 2010 John Wiley & Sons, Ltd.     

Surface anchoring mode‐dependent hydrolysis reactions of hydrazone groups on gold examined by pH‐dependent Raman spectroscopy

We conducted a comparative study of the pH‐dependent anchoring behaviors of 3‐methyl‐2‐benzothiazolinone hydrazone (3M2BH) and benzophenone hydrazone (BPH) on gold nanoparticles (AuNPs) by means of interfacial Raman spectroscopy. We found that several bands of 3M2BH in the highly alkaline pH region disappeared as the colloidal conditions became more neutral and acidic. The vibrational band at 919, 1174, and 1222 cm⁻¹ at pH 10.0 disappeared below pH 9.2, which may be because of the hydrolysis reactions that cleave the labile N―NH₂ group of 3M2BH, indicating a rather perpendicular orientation via the sulfur atom at the surfaces. A fairly high transition pH value was assumed to be because of the interaction of the N―NH₂ group in the vicinity of the surfaces. Several characteristic bands, including 1584 and 1617 cm⁻¹, also exhibited different intensities, suggesting that the adsorbates on Au surfaces underwent structural transformations of the N―NH₂ group after the pH value became neutral or acidic. These changes were not observed for BPH, presumably because of the direct and robust binding of the hydrazone onto Au surfaces. Our results revealed that the pH‐dependent cleavage reactions may vary depending on the surface anchoring modes of the adsorbates. Copyright © 2015 John Wiley & Sons, Ltd.     

Simulation of the Ising model,memory for Bell states and generation of four-atom entangled states in cavity QED

A scheme is proposed to simulate the Ising model and preserve the maximum entangled states (Bell states) in cavity quantum electrodynamics (QED) driven by a classical field with large detuning. In the strong driving and large-detuning regime, the effective Hamiltonian of the system is the same as the standard Ising model, and the scheme can also make the initial four Bell states of two atoms at the maximum entanglement all the time. So it is a simple memory for the maximal entangled states. The system is insensitive to the cavity decay and the thermal field and more immune to decoherence. These advantages can warrant the experimental feasibility of the current scheme. Furthermore, the genuine four-atom entanglement may be acquired via two Bell states through one-step implementation on four two-level atoms in the strong-driven model, and when two Greenberger-Horne-Zeilinger (GHZ) states are prepared in our scheme, the entangled cluster state may be acquired easily. The success probability for the scheme is 1. Supported by the National Natural Science Foundation of China (Grant No. 10774088) and the Key Program of the National Natural Science Foundation of China (Grant No. 10534030)     

Generalized superposition of two squeezed states: generation and statistical properties

Superpositions of squeezed states were introduced by Sanders [Phys. Rev. A 39 (1998) 4284], Schleich et al. [Phys. Rev. A 38 (1988) 1177], Xin et al. [Phys. Rev. A 50 (1994) 2865], to investigate the occurrence of nonclassical properties of the quantized radiation field. In this report we present a generalized superposition state which interpolates between two arbitrary squeezed states. Nonclassical properties of this intermediate state as function of the interpolating parameters are studied, the previous results in the literature becoming a particularization of ours. An experimental proposal to generate this state is also presented.     

Temperature‐dependent,micro‐Raman spectroscopic study of barium titanate nanoparticles

A comparative, temperature‐dependent (80–500 K at 5 K intervals), micro‐Raman spectroscopic study of 300 and 50 nm diameter ceramic BaTiO₃ nanoparticles was carried out with the purpose of elucidating the nanoparticle size effect on the temperature dependence of the polar and non‐polar phonons. A method for calibrating Raman intensities, along with an iterative spectral fitting algorithm, is proposed for concurrent Raman band position and intensity analysis, increasing the analytical abilities of single temperature point Raman spectroscopy. The 300 nm particles exhibit all three phase transitions, whereas the 50 nm particles do not show evidence of these phase transitions in the same temperature range. The Curie temperature appears to be a phonon converging point, irrespective of the phonon symmetry. An attempt was made to qualitatively relate the temperature‐dependent Raman spectra to complimentary non‐spectroscopic methods, such as heat capacity and X‐ray diffraction studies. The study proves that the temperature‐dependent behavior of the polar phonon, 265 cm⁻¹, can be utilized as a sensitive phase transition probe. Copyright © 2014 John Wiley & Sons, Ltd.     

Matrix isolation and IR spectroscopic characterization of 3,5‐difluoropyridyl‐2,4,6‐trinitrene

The photochemistry of 2,4,6‐triazido‐3,5‐difluoropyridine 21 was investigated by matrix infrared and electron paramagnetic resonance spectroscopies. Ultraviolet irradiation (>260 nm) of 21 results in the formation of 3,5‐difluoropyridyl‐2,4,6‐trinitrene 26 in yields high enough for characterization by infrared spectroscopy. The experimental infrared spectrum is in good agreement with density functional theory calculations. Under similar conditions, a very strong electron paramagnetic resonance spectrum of septet trinitrene 26 was obtained. Shorter irradiation times resulted in more complex product mixtures containing, in addition, mononitrenes and dinitrenes. Surprisingly, azirines and keteneimines, the typical photoproducts of arylnitrenes, were not observed. Copyright © 2011 John Wiley & Sons, Ltd.     

Bacterial mixture identification using Raman and surface‐enhanced Raman chemical imaging

The ability of normal Raman and surface‐enhanced Raman scattering (SERS) to identify and detect bacteria has shown great success in recent studies. The addition of silver nanoparticles to bacterial samples not only results in an enhanced Raman signal, but it also suppresses the native fluorescence associated with biological material. In this report, Raman chemical imaging (RCI) was used to analyze individual bacteria and complex mixtures of spores and vegetative cells. RCI uses every pixel or a binned pixel group (BPG) of the Raman camera as an independent Raman spectrograph, allowing collection of spatially resolved Raman spectra. The advantage of this technique resides primarily in the analysis of samples in complex backgrounds without the need for physically isolating or purifying the sample. Using a chemical imaging Raman microscope, we compare normal RCI to SERS‐assisted chemical imaging of mixtures of bacteria. In both cases, we are able to differentiate single bacterium in the Raman microscope's field of view, with a 60‐fold reduction in image acquisition time and a factor of 10 increase in the signal‐to‐noise ratio for SERS chemical imaging over normal RCI. Copyright © 2010 John Wiley & Sons, Ltd.     

Micro‐Raman spectroscopic study of artificially aged natural and dyed wool

The objective of this study was to evaluate the use of micro‐Raman spectroscopy as a non‐invasive vibrational spectroscopic technique applied to the examination of wool samples, which may be applied to textile materials of cultural heritage interest. In this work, a selection of wool materials were primarily investigated in their unaged states through the utility of a natural wool reference together with selected samples dyed with different natural colorants, namely woad, weld and madder. The identification of the main modes of vibration of the wool fibre keratin was assessed in all the samples, which aided the determination of the changes within the protein structure, in particular, through the cysteine and peptide cross‐linkages brought about by the addition of the dyes that can produce effects similar to degradation. The dye too was assessed importantly to enable its identification through its characteristic scattering or fluorescence emissions on a woollen matrix, as well as to ascertain whether a uniform covering across the surface of the wool was achieved or not. Regarding the artificial degradation of the samples it was possible to observe numerous modifications within the molecular structure of the wool, in particular, within the amide I, C H bending, amide III and S‐S stretchings along with the physical photo‐yellowing of fibres given by the presence of lipids dispersed across the surface of the wool. The effects of ageing on the dyed samples were also investigated, indicating that many of the bands relative to the colorants were still present, yet so too were numerous vibrations from the wool that also indicated a certain level of stress and degradation to the underlying wool. Copyright © 2008 John Wiley & Sons, Ltd.     

Raman spectroscopic characteristics of diallyl trisulfide acting on trans‐crotonaldehyde

In this paper, the molecular mechanism of diallyl trisulfide (DATS) on trans‐crotonaldehyde (TCA) was studied by UV–vis absorption and Raman spectroscopies combining with density functional theory calculations. Experimental results indicate that the introduction of DATS can not only make the maximum absorption peak of TCA shift 15 nm, but also obviously alter the Raman vibrational frequency of aldehyde (―CHO). In addition, the Raman intensity of TCA decreased significantly, especially in the presence of mitochondria. Our theoretical calculations reproduce fairly well the experimental data. Copyright © 2015 John Wiley & Sons, Ltd.     

Raman spectroscopic study of the magnesium‐carbonate minerals—artinite and dypingite

Magnesium minerals are important in the understanding of the concept of geosequestration. The two hydrated hydroxy magnesium‐carbonate minerals artinite and dypingite were studied by Raman spectroscopy. Intense bands are observed at 1092 cm⁻¹ for artinite and at 1120 cm⁻¹ for dypingite, attributed ν₁ symmetric stretching mode of CO₃²⁻. The ν₃ antisymmetric stretching vibrations of CO₃²⁻ are extremely weak and are observed at 1412 and 1465 cm⁻¹ for artinite and at 1366, 1447 and 1524 cm⁻¹ for dypingite. Very weak Raman bands at 790 cm⁻¹ for artinite and 800 cm⁻¹ for dypingite are assigned to the CO₃²⁻ν₂ out‐of‐plane bend. The Raman band at 700 cm⁻¹ of artinite and at 725 and 760 cm⁻¹ of dypingite are ascribed to CO₃²⁻ν₂ in‐plane bending mode. The Raman spectrum of artinite in the OH stretching region is characterised by two sets of bands: (1) an intense band at 3593 cm⁻¹ assigned to the MgOH stretching vibrations and (2) the broad profile of overlapping bands at 3030 and 3229 cm⁻¹ attributed to water stretching vibrations. X‐ray diffraction studies show that the minerals are disordered. This is reflected in the difficulty of obtaining Raman spectra of reasonable quality, and explains why the Raman spectra of these minerals have not been previously or sufficiently described. Copyright © 2008 John Wiley & Sons, Ltd.     

Raman spectroscopic study of the multi‐anion uranyl mineral schroeckingerite

Raman spectroscopy complemented with infrared (IR) spectroscopy has been used to study the mineral schroeckingerite. The mineral is a multi‐anion mineral and has (UO₂)²⁺, (SO₄)²⁻ and (CO₃)²⁻ units in its structure, and bands attributed to these vibrating units are readily identified in the Raman spectra. Symmetric stretching modes at 815, 983 and 1092 cm⁻¹ are assigned to (UO₂)²⁺, (SO₄)²⁻ and (CO₃)²⁻ units, respectively. The antisymmetric stretching modes of (UO₂)²⁺, (SO₄)²⁻ are not observed in the Raman spectra but may be readily observed in the IR spectrum at 898 and 1180 cm⁻¹. The antisymmetric stretching mode of (CO₃)²⁻ is observed in the Raman spectrum at 1374 cm⁻¹, as is also the ν₄ (CO₃)²⁻ bending modes at 742 and 707 cm⁻¹. No ν₂ (CO₃)²⁻ bending modes are observed in the Raman spectrum of schroeckingerite. All the spectroscopic evidence points to a highly ordered structure of this mineral. Copyright © 2007 John Wiley & Sons, Ltd.     

Improved charge transfer multiplet method to simulate M‐ and L‐edge X‐ray absorption spectra of metal‐centered excited states

Charge transfer multiplet (CTM) theory is a computationally undemanding and highly mature method for simulating the soft X‐ray spectra of first‐row transition metal complexes. However, CTM theory has seldom been applied to the simulation of excited‐state spectra. In this article, the CTM4XAS software package is extended to simulate M_2,3‐ and L_2,3‐edge spectra for the excited states of first‐row transition metals and also interpret CTM eigenfunctions in terms of Russell–Saunders term symbols. These new programs are used to reinterpret the recently reported excited‐state M_2,3‐edge difference spectra of photogenerated ferrocenium cations and to propose alternative assignments for the electronic state of these cations responsible for the spectroscopic features. These new programs were also used to model the L_2,3‐edge spectra of Fe^II compounds during nuclear relaxation following photoinduced spin crossover and to propose spectroscopic signatures for their vibrationally hot states.