Shifts Of Atoms Research Articles

First-principle calculations study of the ORR/OER electrocatalytic activity of ruthenium polyphthalocyanine axially modified with aliphatic thiol groups.

In this study, the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) catalytic activity of ruthenium polyphthalocyanine axially modified with different aliphatic thiol groups, RuPPc-SR (SR = -SCH3, -SC2H5, -SC3H7, -SC4H9, -SC5H11, and -SC6H13), in an acidic medium were simulated using DFT. All -SR groups can effectively enhance the ORR and OER catalytic activities of RuPPc. The ORR and OER overpotentials of RuPPc-SC4H9 are 0.237 V and 0.436 V, respectively, which are far lower than those of RuPPc (0.960 V and 0.903 V). For RuPPc-SC4H9, the four C and S atoms of the -SC4H9 chain and Ru atom are coplanar, and thus, conjugate effects and inductive effects exist between the -SC4H9 chain and Ru atom. This makes the Ru atom exhibit the least positive Bader charge and smallest spin density, and the anti-bonding orbitals of dxz, dyz, and dz2 of the Ru atom shift below the Fermi level (Ef). This makes the adsorption strength of RuPPc-SC4H9 toward ORR and OER intermediates the weakest, which accelerates the reaction process, thus resulting in better ORR and OER catalytic activity. Therefore, the introduction of the aliphatic thiol groups might effectively improve the OER/ORR catalytic activity of RuPPc.

Pinuseldarone, a Clerodane-Type Diterpene from Pinus eldarica Needles and Phytochemicals as Novel Agents for Regulating Brown Adipogenesis and Thermogenesis.

Phytochemical investigation of the MeOH extract of Pinus eldarica needles led to the isolation and identification of a new clerodane-type diterpene, pinuseldarone (1), along with a known flavonoid, 5,4'-dihydroxy-3,7,8-trimethoxy-6-C-methylflavone (2), through HPLC purification. The structure of the new compound 1 was elucidated using spectroscopic methods, including 1D and 2D NMR, as well as HRESIMS. Its absolute configuration was established through NOESY analysis and computational methods, including electronic circular dichroism (ECD) calculations and gauge-including atomic orbital NMR chemical shift calculations, followed by DP4+ probability analysis. The metabolic implications of the isolated compounds were assessed using a cultured brown adipocyte model derived from murine brown adipose tissue. It was observed that treatment with dihydroxy-3,7,8-trimethoxy-6-C-methylflavone (2) downregulates the adipogenic marker C/EBPδ and fatty acid transporter CD36, resulting in a significant reduction in lipid accumulation during brown adipocyte differentiation. However, pinuseldarone (1) treatment did not affect brown adipocyte differentiation. Interestingly, pretreatment with pinuseldarone (1) potentiated the pharmacological stimulation of brown adipocytes, seemingly achieved by sensitizing their response to β3-adrenoreceptor signaling. Therefore, our findings indicate that phytochemicals derived from P. eldarica needles could potentially serve as valuable compounds for adjusting the metabolic activity of brown adipose tissue, a vital component in maintaining whole-body metabolic homeostasis.

Preparation and response behaviour of wormlike micelles in response to CO2 stimulation

Low-permeability reservoirs have a lot of reserves, but there is the phenomenon that gas injection is prone to gas flushing during the development process. CO2 foam drive combines the dual advantages of CO2 drive and foam drive, which can significantly lessen CO2 gas flushing and expand the wave efficiency of the replacement phase. The conventional CO2 foam system contains a large number of foaming agents and foam stabilizers. Still, there are issues such as high viscosity of the extracted fluid, serious emulsification, and difficulty in foam defoaming, which leads to the difficulty and high cost of treating the extracted fluid. In this study, the best performing wormlike micelles system of 0.6 wt% DOAPA@NaSal-H+ to stabilise the CO2 foam system was prepared by preferring N, N-dimethyl-3-oleamidopropylamine (DOAPA) and sodium salicylate (NaSal), using foam performance as an indicator. Analytical tests include conductivity test, rheological property test, surface tension test, Cryo-SEM, DLS are employed. According to the findings, the system under the influence of CO2 exhibits an increase in the chemical shift of hydrogen atoms near the N atom, an increase in the conductivity of the system, a lamellar mesh microstructure, and an average particle size of micelles of 104.6 nm. The surface tension of DOAPA@NaSal-H+ decreases with the increase of concentration, and the apparent viscosity decreases with the increase of shear rate, which exhibits the typical viscoelastic fluid behaviour. It is important to study the stimulus-response rows of CO2 stimulus responsive wormlike micelles, which provides theoretical support for the stabilization of CO2 foams by wormlike micelles.

Quantum Chemical and Biological Properties of Coumarin Derivative Compound

This work presents the characterization of 8-t-buthyl-4-methyl-2H- chromen 2-one by quantum chemical calculations and spectral techniques. The molecular geometry, vibrational frequencies and gauge including atomic orbital (GIAO) 1H and 13C NMR chemical shift values of title compound in the ground state have been calculated using the density functional method (B3LYP) with the 6-31G(d) basis set. The theoretical vibrational frequencies and chemical shift values show good agreement with experimental values. In addition, DFT calculations of molecular electrostatic potentials and frontier molecular orbitals of the title were carried out at the B3LYP/6-31G(d) level of theory. The title compound was screened for antibacterial, antifungal and antioxidant activities.

Review of Systematic Tendencies in (001), (011) and (111) Surfaces Using B3PW as Well as B3LYP Computations of BaTiO3, CaTiO3, PbTiO3, SrTiO3, BaZrO3, CaZrO3, PbZrO3 and SrZrO3 Perovskites.

We performed B3PW and B3LYP computations for BaTiO3 (BTO), CaTiO3 (CTO), PbTiO3 (PTO), SrTiO3 (STO), BaZrO3 (BZO), CaZrO3 (CZO), PbZrO3 (PZO) and SrZrO3 (SZO) perovskite neutral (001) along with polar (011) as well as (111) surfaces. For the neutral AO- as well as BO2-terminated (001) surfaces, in most cases, all upper-layer atoms relax inwards, although the second-layer atoms shift outwards. On the (001) BO2-terminated surface, the second-layer metal atoms, as a rule, exhibit larger atomic relaxations than the second-layer O atoms. For most ABO3 perovskites, the (001) surface rumpling s is bigger for the AO- than BO2-terminated surfaces. In contrast, the surface energies, for both (001) terminations, are practically identical. Conversely, different (011) surface terminations exhibit quite different surface energies for the O-terminated, A-terminated and BO-terminated surfaces. Our computed ABO3 perovskite (111) surface energies are always significantly larger than the neutral (001) as well as polar (011) surface energies. Our computed ABO3 perovskite bulk B-O chemical bond covalency increases near their neutral (001) and especially polar (011) surfaces.

Stability of monomeric indigo in the electronic ground state: An experimental matrix isolation infrared and theoretical study

Monomers of indigo were investigated using experimental (matrix-isolation) and theoretical methods. For the first time, the infrared spectrum of indigo molecules isolated in low-temperature Ar matrices was recorded and subjected to a detailed theoretical analysis. An excellent agreement between the experimental spectrum of indigo monomers and the spectrum theoretically predicted for the highly-symmetric (C2h) most stable dioxo form of the compound allowed a very reliable assignment of the observed infrared absorption bands. Matrix-isolated monomers of indigo were exposed to UV–vis radiation of different wavelengths. The conducted experiments demonstrated that molecules of indigo do not undergo any structural changes, even under irradiation with short-wavelength UV (λ > 200 nm) light. Theoretical calculations concerning the stability of photoproducts that could be potentially generated from indigo were conducted. The calculations carried out for the species generated by hydrogen-atom transfer from N1′ to O atom attached to the opposite ring revealed that both the oxo-hydroxy and dihydroxy tautomers of indigo should be unstable in the ground electronic state. The calculations carried out for the C2H tautomer (which may be generated by a hydrogen atom shift from N1′ to C2 of the opposite ring) led to optimization of the structure that is potentially stable, but very much distorted from planarity.

MASAP: A package for atomic scattering amplitude in solids

We present the MsSpec Atomic Scattering Amplitude Package (MASAP), composed of a computation program and a graphical interface to generate atomic scattering amplitude (ASA) of an atom, either isolated or embedded in an environment, at any chosen energy of the impinging electron up to ≈15 KeV. The ASA is calculated using an effective, complex optical potential which provides damping effects in the scattering process in a fully relativistic framework. Optionally, scalar relativistic and non-relativistic approximations are also available to assess their applicability to a given problem. In order to describe electron propagation in solids we suggest to replace ASA's based on Plane Waves (PW) scattering with effective ASA's based on curved Spherical Waves (SW) using truncated-overlapped potentials of the Muffin-Tin (MT) type constructed according to the Mattheiss prescription. The graphical user interface generates not only ASA data files providing atomic Differential Cross Sections (DCS) but also files of related quantities such as total Cross Section (CS), both elastic and inelastic, atomic tl-matrices and phase shifts. We found in general that the imaginary part of the optical potential enhances the calculated elastic DCSs in the forward direction compared to the same potential without the imaginary part, a feature related to the optical theorem, but gives rise to a lower intensity at all other directions as expected due to the damping effect of the complex part of the potential. We show calculated differential and transport Cross Sections for aluminum and gold atoms both in isolation and in crystals with the Face-Centered-Cubic (FCC) structure. Program summaryProgram Title: MASAPCPC Library link to program files:https://doi.org/10.17632/gtxp3mn5hs.1Licensing provisions: Apache 2.0Programming language: FORTRAN 77, Python3External routines:•SciPy (https://www.scipy.org)•Atomic Simulation Environment (https://wiki.fysik.dtu.dk/ase/)•h5py (https://www.h5py.org)•wxPython (https://www.wxpython.org)Nature of problem: Calculation of atomic scattering amplitudes of scattered electrons by an embedded atom in a solid including damping and relativistic effects. Comparison between ASA's in an isolated atomic system and a solid. Introduction of an effective ASA for electrons propagating in a solid derived from Multiple Scattering Theory.Solution method: Potential scattering theory. Muffin-tin approximation. Superposition of atomic electron densities obtained by self-consistent Dirac-Fock atomic calculations. Hedin-Lundqvist potential as an optical potential. Fully relativistic theory, with scalar-relativistic and non-relativistic approximations for comparison.Additional comments including restrictions and unusual features: Even though the program can perform calculations at impinging electron energies up to ≈15 Kev, DCS calculations are recommended in the range 50 : ≈1500 eV both in the case of isolated atoms and atoms embedded in solids, since this interval is more suitable for studying the details of the atomic potentials in their environment.In the case of solids, at energies lower than ≈50 eV, the details of the electronic structure might be important, whereas in the case of isolated atoms this range might suffer from the neglect of the polarization potential and coupling to available inelastic channels. In this respect an option to add an empirical form of a polarization potential to investigate its effects is available to the interested user.

Assignment of the disordered, proline-rich N-terminal domain of the tumour suppressor p53 protein using 1HN and 1Hα-detected NMR measurements

Protein p53 is mostly known for playing a key role in tumour suppression, and mutations in the p53 gene are amongst the most frequent genomic events accompanying oncogenic transformation. Continuous research is conducted to target disordered proteins/protein regions for cancer therapy, for which atomic level information is also necessary. The disordered N-terminal part of p53 contains the transactivation and the proline-rich domains—which besides being abundant in proline residues—contains repetitive Pro-Ala motifs. NMR assignment of such repetitive, proline-rich regions is challenging due to the lack of amide protons in the 1HN-detected approaches, as well as due to the small chemical shift dispersion. In the present study we perform the full assignment of the p531–100 region by applying a combination of 1HN- and 1Hα-detected NMR experiments. We also show the increased information content when using real-time homo- and heteronuclear decoupled acquisition schemes. On the other hand, we highlight the presence of minor proline species, and using Pro-selective experiments we determine the corresponding cis or trans conformation. Secondary chemical shifts for (Cα–Cβ) atoms indicate the disordered nature of this region, with expected helical tendency for the TAD1 region. As the role of the proline-rich domain is yet not well understood our results can contribute to further successful investigations.

Site-specific relaxation of peptide bond planarity induced by electrically attracted proton/deuteron observed by neutron crystallography.

In structural biology, peptide bonds, fundamental linkages between hundreds of amino acids, of which a protein molecule is composed, have been commonly treated as a plane structure just as Linus Pauling et al. proposed. In this paper, a site-specific peptide bond relaxation mechanism by deuterons whose localization has been suggested by neutron crystallography is proposed. Such deuteron was observed as an arm of neutron scattering length density protruding from the carbonyl oxygen atoms in the main chain in the omit map drawn by neutron crystallography of human lysozyme. Our comprehensive study using x-ray and neutron diffraction and 15 N chemical shifts of individual amide nitrogen atoms within the same peptide bond strongly suggests the relaxation of the electronic resonance structure because of site-specific modulation by protons/deuterons localized on the electron orbital of the carbonyl oxygen. All experimental data used in this examination were obtained at room temperature, which is preferable for enzymatic activity. Such a close interaction between the electron resonance structure of a peptide bond and the exchangeable protons/deuterons well agreed with that observed in an intermediate state in an amide hydrolytic reaction simulated by the ab-initio calculation including water molecules.

Grain structure and co-precipitation behavior of high-Zn containing Al–Zn–Mg–Cu aluminium alloys during deformation via high-temperature upsetting-extrusion

A study on the deformation behavior with increase in strain during upsetting-extrusion (UE) was studied (i.e., No-UE, Small-UE, and Large-UE strains) at 350 °C in Al-8.9Zn-2.2Mg-2.1Cu-0.14Zr-0.02Sc (wt%) alloys to evaluate the strengthening effects of grain size/texture and co-precipitation for different ageing (i.e., as-received, T4, and T6 aging) conditions. In as-received samples, electron back-scattered diffraction observations revealed that increasing UE strain enhances the formation of continuous and discontinuous dynamic recrystallization grains. This reduces the size difference between fine and coarse grains in bimodal structure and produces stronger copper/cubic texture. In small angle X-ray scattering (SAXS), a large UE strain brings about more fraction of Y-phase and GP zones. In T4 Large-UE samples, SAXS indicated higher size stability of disk-like Y-phase. High-angle annular dark field scanning transmission electron microscopy images revealed five-layered atomic arrangement of a unit cell of Y-phase, where the center layer was composed of Al and sandwiched layers, 2Cu/2Zn/2Cu and Al/ZnCu/ZnCu/Al. In T6 Large-UE samples, it was observed that the growth of Y-phase is accompanied by intrinsic atomic shift along the [101̅0]Y-phase direction. Furthermore, SAXS quantitatively showed size evolution of η'/η precipitates and formation of a higher aspect ratio of Y-phase. The collective effects of finer bimodal grain structure, stronger fiber texture, and co-precipitation of Y-phase and η'/η precipitates provide evidence higher ultimate tensile strength (∼766 ± 5 MPa) and superior strain (∼10.9 ± 0.4) of large-UE strain samples under T6 ageing.

Atmospheric oxidation of (E)-β-farnesene initiated by hydroxyl radical: New formation mechanism of HOMs

(E)-β-farnesene is one of the acyclic sesquiterpenes, whose atmospheric oxidation has been determined as a significant contributor to SOA formation due to the formed highly oxidized multifunctional molecules (HOMs). In this work, the atmospheric oxidation of (E)-β-farnesene initiated by OH radical was comprehensively investigated using quantum chemical calculation. For the initial reactions, OH addition reactions are dominant over H atom abstraction reactions because of lower free energy barriers. The first-generation products involving acetone, (E)− 4-methyl-8-methylenedeca-4,9-dienal, 4-methylenehex-5-enal (P3), 6-methylhept-5-en-2-one (P4), formaldehyde, (E)− 7,11-dimethyldodeca-1,6,10-trien-3-one and (E)− 6,10-dimethyl-2-methyleneundeca-5,9-dienal are produced from the subsequent reactions of the OH-(E)-β-farnesene adducts with NO and HO2. The second-generation products, such as 4-oxopentanal, 4-methylenehex-5-enal, (E)− 4-methyl-8-oxodeca-4,9-dienal, formaldehyde and (E)− 4-methyl-8-methylenenon-4-enedial, are also determined from the successive oxidations of P2 and P3 under high and low NOx conditions. For the formation of HOMs, the H atom shift is the bottleneck for the autooxidation mechanism while our newly proposed mechanism, i.e. the multiple H abstractions by OH radical and reactions with O2 and HO2, is a more thermodynamically favorable formation pathway of the HOMs. Due to the intricate oxidation mechanisms and products, it is difficult to comprise the oxidation mechanisms of sesquiterpenes (including (E)-β-farnesene) in the atmospheric chemical models to thoroughly evaluate their contributions to SOA formation. We expect that this comprehensive oxidation mechanism of (E)-β-farnesene from a theoretical perspective would be conducive to clarifying the atmospheric fate of (E)-β-farnesene and even sesquiterpenes.

Beam shifts controlled by orbital angular momentum in a guided-surface plasmon resonance structure with a four-level atomic medium.

We proposed a scheme to realize tunable giant Goos-Hänchen (GH) and Imbert Fedorov (IF) shifts of the Laguerre-Gauss (LG) beam on a guided-wave surface plasmon resonance (GWSPR) structure backed by a coherent atomic medium with the spontaneously generated coherence (SGC) effect. The orbital angular momentum carried by the incident LG beam can be applied to enhance and control IF shifts but is not beneficial to GH shifts. However, in the presence of SGC effect in the atomic medium, both GH and IF shifts can be simultaneously enhanced and well controlled. With the SGC effect, the linear absorption of the atomic medium vanishes, while the nonlinear absorption of that can be significantly enhanced and controlled by the trigger field, which contributes to controlling of the beam shifts. In particular, the direction of GH shifts can be switched by the Rabi frequency of the trigger field, which can be interpreted as the result of a competition between the inherent damping and the radiative damping corresponding to the nontrivial change in the loci of the reflection coefficients. This scheme provides an effective method to flexibly control and enhance the beam shifts, so it has potential applications in integrated optics, optical sensors, etc.

DFT Approach for Predicting 13C NMR Shifts of Atoms Directly Coordinated to Pd

DFT Approach for Predicting ¹³C NMR Shifts of Atoms Directly Coordinated to Pd

Crystal Structure and Photocatalytic Properties of the CsV0.625Te1.375O6 Mixed‐Valence β‐Pyrochlore Compound

AbstractA new β‐pyrochlore compound with complex composition of Cs(V3+0.0625V5+0.5625Te4+0.34375Te6+1.03125)O6 has been synthesized by a solid‐state reaction and characterized by single‐crystal X‐ray diffraction and thermal analysis. The compound possesses the typical cubic symmetry with space group , however some of the oxygen atoms shift from the special position 48 f to the general crystallographic positions 32e, 96 g and 96 h. This shift is caused by complex B‐site composition with mixed‐valence vanadium and tellurium atoms, especially the presence of the large Te4+ ion. The locations of the valence band and conduction band edges were determined experimentally under vacuum conditions by X‐ray photoelectron spectroscopy, UV‐visible and impedance spectroscopy and evaluated theoretically for water solutions. The photocatalytic ability of the compound under visible light irradiation was determined using the methylene blue decomposition process as an example. The nature of the active radical species and possible dye degradation pathway were suggested according to experimental data.

Improving the Sensitivity of Enantioanalysis with Densely Fluorinated NMR Probes.

Nuclear magnetic resonance (NMR) spectroscopy has long been utilized as a classic method for chiral discrimination of enantiomers. However, its sensitivity limitations have hindered the detection of analytes at low concentrations. In this study, we present our efforts to overcome this challenge by employing chiral NMR probes that are labeled with a significant number of chemically equivalent 19F atoms. Specifically, we have designed and synthesized three chiral palladium pincer complexes, all of which are labeled with nonafluoro-tert-butoxy groups to enhance detectability. The recognition of enantiomers with the probe induces distinct changes in microenvironments, resulting in differential perturbations on the chemical shift of the 19F atoms in proximity. This method is applicable to the enantiodifferentiation of various amines, amino alcohols, and amino acid esters. The abundance of 19F atoms enables the detection of chiral analytes at low concentrations, which is otherwise challenging to achieve through traditional 1H NMR-based analysis. Two of the probes are constructed with asymmetric pincer ligands with structurally varied sidearms, allowing for facile manipulation of the chiral binding pocket. The C2 symmetrical probe possesses 36 equivalent 19F atoms, enabling the determination of enantiocomposition of samples with concentrations in the low micromolar range.

Pulse Cycle Dependent Nondipole Effects in Above-Threshold Ionization

In this study, we employ strong field approximation (SFA) to investigate the influence of the number of pulse cycles on above-threshold ionization within the framework of nondipole theory. The SFA enables the analysis of the ionization process under the dominance of the electric field, compared to other factors such as the binding potential of an atom. Nondipole effects, including higher-order multipole fields, can significantly impact ionization dynamics. However, the interaction between nondipole effects and pulse cycles remains unclear. Therefore, we investigate the pulse cycle dependence of ionization and examine peak shifts in Kr and Ar atoms. Our findings have implications for comprehensively understanding the effects of electromagnetic fields on electron behavior. The insights gained from this study provide valuable guidance for future research in strong field ionization.

Bioactivity and quantum chemical calculations оf a new coumarine derivative as a strong antioxidant, antimicrobial and anti-cancer substance

4-(((4-Ethyl-5-(thiophen-2-yl)-4H-1,2,4-triazol-3-yl)thio)methyl)-7-methyl-coumarin was synthesized, and its characterization was done with quantum chemical calculations and spectral techniques. The density functional method (B3LYP) with the 6-311G(d,p) basis set was used to calculate the molecular geometry, vibrational frequencies, and gauge, including atomic orbital (GIAO) 1H and 13C-NMR chemical shift values of the title compound in the ground state. The theoretical vibrational frequencies and chemical shift values agree well with the experimental results. DFT calculations of the density of states (DOS) and frontier molecular orbitals of the title compound were carried out at the B3LYP/6-311G(d,p) level of theory. In the present study, biological activities and molecular docking studies of this triazole ring containing coumarin derivative compound were carried out. Interactions with important residues in active sites were detected in molecular docking studies. In addition, in vitro analysis has shown that anti-microorganism activity is especially effective against bacterial organisms such as E. coli, S. aureus, B. cereus, and fungal organisms such as C. albicans, C. tropicalis. Also, the antioxidant capacity of the test compound was investigated by oxidative stress index (OSI) and radical scavenging power (DPPH.), and its antioxidant potential was found. In addition, it was determined by in vitro anticancer and SDS-PAGE analysis that the test compound does not cause a detrimental cytotoxic effect on healthy cell cultures such as HUVEC and has the potential for anticarcinogenic activity on MCF-7 and MKN-45 cancerous cell cultures.

Prediction of chemical bond breaking in insensitive high-energy energetic materials at high temperature and pressure

The bond breaking of energetic materials under the action of temperature and pressure has always been a key step in understanding the explosive mechanism of energetic materials. In this work, we use the mean square shift of atoms and the theoretical bond breaking position of chemical bonds to give the bond breaking temperature of each chemical bond of insensitive high-energy energetic materials, 1,1-diamino-2,2-dinitroethylene (α-FOX-7) and 1,3,5-triamino-2,4,6-trinitrobenzene (TATB), at 0 and 30 GPa. The calculation results show that the bond breaking sequence of α-FOX-7 and TATB in the selected pressure range is N–H, N–O, C–NO2, and C–NH2. At the same time, the difference in the sensitivity between α-FOX-7 and TATB was discussed through the analysis of partial chemical bond breaking temperature.

Multinuclear solid state nuclear magnetic resonance for studying CsPbBr3 nanocubes

Abstract Cesium lead bromide perovskite (CsPbBr3) nanocrystals have raised impressive interest as efficient and stable optoelectronic materials. Size and morphology play important roles in the final performances of these materials and advanced characterization studies are needed to elucidate structural and surface properties. In this work, CsPbBr3 cubic nanocrystals were obtained by colloidal synthesis and characterized by multinuclear Solid State NMR (SSNMR), complemented by X-Ray Diffraction (XRD), Transmission Electron Microscopy (TEM) and optical spectroscopy. The multinuclear NMR approach allowed the different components of the nanocubes to be separately observed. In particular, the surface ligands and their interactions with the nanocubes surface were investigated by 1H and 13C NMR experiments, while the structural investigation of the perovskite nanocubes was addressed by exploiting 207Pb and 133Cs spectral properties in comparison with bulk CsPbBr3. Static 207Pb NMR spectra indicated a possible contribution of chemical shift anisotropy from the 207Pb nuclei of the outer layer. The 133Cs NMR spectra showed signals with different chemical shifts for cesium atoms in at least three regions of the nanocubes, from the inner core to the surface, which were interpreted in terms of cubic layers with different distances from the surface using a simple geometrical model. This interpretation was also supported by 133Cs longitudinal relaxation time measurements.

Spatially dependent Lamb shift in a waveguide and its influence on the optical polyatomic cooperative effects

We show that the Lamb shift can significantly affect the nature of the interatomic dipole-dipole interaction in structured reservoirs. The effect is explained by the difference in the Lamb shift for atoms located at different positions due to the inhomogeneity of the spatial structure of the modes of the electromagnetic field. Based on the model system involving two atoms in a waveguide, we demonstrate that this difference can be the same order as the natural linewidth of the atomic transition.