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Статті в журналах з теми "Ground-state CO molecules"
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Blokland, Janneke H., Jens Riedel, Stephan Putzke, Boris G. Sartakov, Gerrit C. Groenenboom, and Gerard Meijer. "Producing translationally cold, ground-state CO molecules." Journal of Chemical Physics 135, no. 11 (September 21, 2011): 114201. http://dx.doi.org/10.1063/1.3637037.
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Huang Yun-Xia, Xu Shu-Wu, and Yang Xiao-Hua. "Orientation of ground-state CO (X1∑+) molecules by combined electrostatic and laser fields." Acta Physica Sinica 61, no. 24 (2012): 243701. http://dx.doi.org/10.7498/aps.61.243701.
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ZHU, JUN, XIU-RONG ZHANG, PEI-YING HUO, and ZHI-CHENG YU. "STRUCTURE STABILITY AND ELECTRONIC PROPERTIES OF CumConCO (m+n=2–7) CLUSTERS." Surface Review and Letters 24, no. 04 (August 25, 2016): 1750049. http://dx.doi.org/10.1142/s0218625x17500494.
Повний текст джерелаАнотація:
The structure stability and electronic properties of CumConCO ([Formula: see text]–7) clusters have been systematically investigated using density functional theory (DFT) within the generalized gradient approximation (GGA). The results indicate that the ground state structures of CumConCO clusters obtained by adsorbing CO molecules on the top sites of stable CumConclusters with C atoms and CO molecules have been activated during adsorption process. Cu2CO, CuCoCO, Cu3CoCO, Co4CO, Cu4CoCO and Cu3Co3CO clusters are stronger than other ground state clusters in thermodynamic stability. Cu2CO, Cu4CO and Cu6CO clusters show stronger chemical stability; Co2CO, Co4CO, Cu5CoCO, Cu3Co3CO, Cu2Co5CO and Co7CO clusters show better propensity to adsorb CO for these clusters have larger adsorption energies; Electronic states of Cu2Co3CO, CuCo4CO, Co5CO, Cu4Co3CO, Cu3Co4CO, CuCo6CO and Co7CO clusters are mainly influenced by those of 3d orbitals in Co and Cu atoms, the contribution to total magnetic moments of these clusters comes mainly from Co atoms and these clusters have high magnetism.
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Chen, Li, Jascha A. Lau, Dirk Schwarzer, Jörg Meyer, Varun B. Verma, and Alec M. Wodtke. "The Sommerfeld ground-wave limit for a molecule adsorbed at a surface." Science 363, no. 6423 (December 13, 2018): 158–61. http://dx.doi.org/10.1126/science.aav4278.
Повний текст джерелаАнотація:
Using a mid-infrared emission spectrometer based on a superconducting nanowire single-photon detector, we observed the dynamics of vibrational energy pooling of carbon monoxide (CO) adsorbed at the surface of a sodium chloride (NaCl) crystal. After exciting a majority of the CO molecules to their first vibrationally excited state (v = 1), we observed infrared emission from states up to v = 27. Kinetic Monte Carlo simulations showed that vibrational energy collects in a few CO molecules at the expense of those up to eight lattice sites away by selective excitation of NaCl’s transverse phonons. The vibrating CO molecules behave like classical oscillating dipoles, losing their energy to NaCl lattice vibrations via the electromagnetic near-field. This is analogous to Sommerfeld’s description of radio transmission along Earth’s surface by ground waves.
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Al-Othman, A. B., and A. S. Sandouqa. "Comparison study of bound states for diatomic molecules using Kratzer, Morse, and modified Morse potentials." Physica Scripta 97, no. 3 (February 15, 2022): 035401. http://dx.doi.org/10.1088/1402-4896/ac514c.
Повний текст джерелаАнотація:
Abstract In this paper, the bound-state energy eigenvalues for several diatomic molecules (O2, I2, N2, H2, CO, NO, LiH, HCl) are computed for various quantum numbers using the shifted 1/N expansion method with the Kratzer, Morse and Modified Morse potentials. Numerical results of the energy eigenvalues for the selected diatomic molecules are discussed. Our results for energy eigenvalues agree perfectly with the results obtained in the literature. A comparative study is performed for four diatomic molecules (H2, N2, CO and HCl) in their ground states using the three potentials.
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Gaume, Ralph A. "The Ground State Hydroxyl Masers Associated with OH 340.78–0.10." Symposium - International Astronomical Union 129 (1988): 251–52. http://dx.doi.org/10.1017/s007418090013459x.
Повний текст джерелаАнотація:
The dynamics of the molecular envelopes surrounding ultracompact H II regions has been the subject of much debate. Since the envelopes often exhibit molecular line emission, line observations have been the primary method of probing these circumstellar shells. The existence of expansive motions in the molecular clouds surrounding massive newly formed stars has been firmly established. Proper motion studies of galactic water masers indicate general expansion, whereas high resolution CO studies often show collimated bipolar outflows centered on continuum H II regions. Maps of the OH maser emission, often associated with these regions, show the masers scattered, apparently randomly, in both position and velocity across an area a few arcseconds in size. Typical velocity ranges for the associated OH maser emission are on the order of 10 km s−1. A number of models of the dynamical and physical conditions of the masing envelope have been developed to explain the properties of specific regions, e.g., collapsing remnant accretion envelopes, rotating disks or tori of neutral material, and expanding shells of shocked material. There is evidence from comparing the velocities of the OH masers to that of recombination lines associated with the underlying H II regions that in most sources the OH masers are formed in material still accreting toward the central object (Garay et al., 1985) (however see Welch and Marr, 1986). Mirabel et al., 1986, have reported the detection of (thermal and subthermal) high velocity OH outflow in several regions of star formation, demonstrating that OH molecules, at least in some instances, are also involved in collimated flows from central stellar objects.
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Li, Xiaohong, Bocheng Ding, Yunfei Feng, Ruichang Wu, Lifang Tian, Jianye Huang, and Xiaojing Liu. "High Energy Inner Shell Photoelectron Diffraction in CO2." Chinese Physics Letters 39, no. 3 (March 1, 2022): 033401. http://dx.doi.org/10.1088/0256-307x/39/3/033401.
Повний текст джерелаАнотація:
Photoelectron diffraction is an effective tool to probe the structures of molecules. The higher the photoelectron kinetic energy is, the higher order the diffraction pattern is disclosed in. Up to date, either the multi-atomic molecule with the photoelectron kinetic energy below 150 eV or the diatomic molecule with 735 eV photoelectron has been experimentally reported. In this study, we measured the diffraction pattern of C 1s and O 1s photoelectrons in CO2 with 319.7 and 433.5 eV kinetic energies, respectively. The extracted C–O bond lengths are longer than the C–O bond length at the ground state, which is attributed to the asymmetric fragmentation that preferentially occurs at the longer chemical bond side during the zero-energy asymmetric vibration.
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Klein, Hans-Friedrich, Alexandra Brand, and Gerhard Cordier. "Synthesis and Reactions with CO and C2H4 of Cobalt(I) Complexes Containing Trimethylphosphine and Chelating o-Diphenylphosphanyl- phenolate Ligands." Zeitschrift für Naturforschung B 53, no. 3 (March 1, 1998): 307–14. http://dx.doi.org/10.1515/znb-1998-0309.
Повний текст джерелаАнотація:
Abstract In tetracoordinate cobalt(I) halide compounds CoX(Ph2P⌒O H)(PMe3)2 (X = CI, Br) o-phos-phanylphenols PhaP⌒OH are coordinated as phosphane ligands. In the presence of base chelat ing anions Ph2P⌒O- give rise to pentacoordinate com plexes Co(Ph2P⌒O)(PMe3)3. Molecular structures are presented for both types of compounds. The five-membered chelate ring in Co(Ph2P⌒O)(PMe3)3 is resistant to protonation, and ring-opening is not observed in the presence of CO or C2H4. Replacing one of the trimethylphosphanes by one of the π-acceptor ligands affords fluxional complex molecules which upon cooling attain definite ground-state geometries out of a multitude of possible isomers.
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Harvey, Pierre D., Marielle Crozet, and Khin T. Aye. "Photoinduced addition of dioxygen molecules in the unsaturated sites of the Pd3(dppm)3CO2+ catalyst." Canadian Journal of Chemistry 73, no. 1 (January 1, 1995): 123–30. http://dx.doi.org/10.1139/v95-019.
Повний текст джерелаАнотація:
The photoinduced addition of O2 onto the unsaturated cluster Pd3(dppm)3CO2+ (as a CF3CO2− salt) in acetonitrile is reported. The final product Pd3(dppm)3(O2)22+(v(O2) = 838 and 866 cm−1) is formed in a multi-step fashion in which two photochemical intermediates are observed (presumably Pd3(dppm)3(O2)(CO)2+ and Pd3(dppm)3(O2)2+. No X-ray structure could be obtained, but numerous spectroscopic findings demonstrate that O2 binds the Pd3 center as a peroxo-O2, and acts as a two-electron donor that triply bridges the metal atoms (forming a 44-electron cluster). The very small excited state lifetimes (between 25 and 35 ± 10 ps) obtained by picosecond flash photolysis indicate that the primary photoreaction is unimolecular, and demonstrate that the first photochemically added O2 molecule must be preassembled in the excited state prior to any photoinduced transformation. This [Formula: see text] ground state complex is responsible for the photoinduced production of the bisdioxygen compound and can be observed by UV–visible spectroscopy. The low efficiency of the photoreaction (quantum yield (Φ) = 0.033 ± 0.004) is explained by the very short excited state lifetime at 298 K, and the competition of O2 with solvent molecules to occupy the unsaturated site of the empty cavity in Pd3(dppm)3CO2+ (i.e., ground state guest–host chemistry). The binding constant for O2 with Pd3(dppm)3CO2+ is roughly estimated to range between 1 and 730 M−1 in the ground state and is considered to be weak. Keywords: clusters, photochemistry, guest–host, oxidation, dioxygen.
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Wakabayashi, Tomonari, Urszula Szczepaniak, Kaito Tanaka, Satomi Saito, Keisuke Fukumoto, Riku Ohnishi, Kazunori Ozaki, et al. "Phosphorescence of Hydrogen-Capped Linear Polyyne Molecules C8H2, C10H2 and C12H2 in Solid Hexane Matrices at 20 K." Photochem 2, no. 1 (February 28, 2022): 181–201. http://dx.doi.org/10.3390/photochem2010014.
Повний текст джерелаАнотація:
Laser-ablated polyyne molecules, H(C≡C)nH, were separated by size in solutions and co-condensed with excess hexane molecules at a cryogenic temperature of 20 K in a vacuum system. The solid matrix samples containing C8H2, C10H2, and C12H2 molecules were irradiated with UV laser pulses and the phosphorescence 0–0 band was observed at 532, 605, and 659 nm, respectively. Vibrational progression was observed for the symmetric stretching mode of the carbon chain in the ground state with increments of ~2190 cm−1 for C8H2, ~2120 cm−1 for C10H2, and ~2090 cm−1 for C12H2. Temporal decay analysis of the phosphorescence intensity revealed the lifetimes of the triplet state as ~30 ms for C8H2, ~8 ms for C10H2, and ~4 ms for C12H2. The phosphorescence excitation spectrum reproduces UV absorption spectra in the hexane solution and in the gas phase at ambient temperature, although the excitation energy was redshifted. The symmetry-forbidden vibronic transitions were observed for C10H2 by lower excitation energies of 25,500–31,000 cm−1 (320–390 nm). Detailed phosphorescence excitation patterns are discussed along the interaction of the polyyne molecule and solvent molecules of hexane.
Дисертації з теми "Ground-state CO molecules"
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Verde, Maurizio. "Simulation of optical dipole trapping of cold CO molecules." Doctoral thesis, 2020. http://hdl.handle.net/2158/1191549.
Повний текст джерелаАнотація:
Ultracold matter offers a unique capability to reach the best high-precision spectroscopy measurements and leads to exciting perspectives in many different areas of science and technology. Molecules, thanks to their complex spectra, couple with a broader range of photons compared to atoms, so they are extremely attractive for fundamental science or to design new quantum technologies. However, to date, only a few molecular species have been brought to temperatures of the order of the microkelvin. This was done by laser cooling, a process that has been demonstrated only for species featuring an unpaired electron that does not participate to the chemical bond.
A different approach, which is indifferent to the molecule electronic structure and thus potentially universal, is sympathetic cooling, where neutral molecules are cooled in a bath of ultracold atoms. However, inelastic collisions between molecules and the coolant is a major obstacle that has hindered the advances of this method thus far. Trapping the molecules in their absolute ground state would circumvent this problem or at least greatly simplify it. In this thesis we simulate the feasibility of an experiment in which metastable CO molecules are first slowed down to a few m/s with a microstructured Stark decelerator, then they are stopped by a strong DC electrical barrier and finally they are transferred irreversibly to their absolute ground state and captured in an optical trap.
Unfortunately, the results of the simulations indicate that the total number of molecules that can be accumulated in the optical trap is rather low, far behind the observation threshold. Therefore, we concluded that other approaches to produce ultracold molecules must to be searched.
Частини книг з теми "Ground-state CO molecules"
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Baer, Tomas, and William L. Hase. "State Preparation and Intramolecular Vibrational Energy Redistribution." In Unimolecular Reaction Dynamics. Oxford University Press, 1996. http://dx.doi.org/10.1093/oso/9780195074949.003.0006.
Повний текст джерелаАнотація:
The first step in a unimolecular reaction involves energizing the reactant molecule above its decomposition threshold. An accurate description of the ensuing unimolecular reaction requires an understanding of the state prepared by this energization process. In the first part of this chapter experimental procedures for energizing a reactant molecule are reviewed. This is followed by a description of the vibrational/rotational states prepared for both small and large molecules. For many experimental situations a superposition state is prepared, so that intramolecular vibrational energy redistribution (IVR) may occur (Parmenter, 1982). IVR is first discussed quantum mechanically from both time-dependent and time-independent perspectives. The chapter ends with a discussion of classical trajectory studies of IVR. A number of different experimental methods have been used to energize a unimolecular reactant. Energization can take place by transfer of energy in a bimolecular collision, as in . . . C2H6 + Ar → C2H6* + Ar . . . . . . (4.1) . . . Another method which involves molecular collisions is chemical activation. Here the excited unimolecular reactant is prepared by the potential energy released in a reactive collision such as . . . F + C2H4 → C2H4F* . . . . . . (4.2) . . . The excited C2H4F molecule can redissociate to the reactants F + C2H4 or form the new products H + C2H3F. Vibrationally excited molecules can also be prepared by absorption of electromagnetic radiation. A widely used method involves initial electronic excitation by absorption of one photon of visible or ultraviolet radiation. After this excitation, many molecules undergo rapid radiationless transitions (i.e., intersystem crossing or internal conversion) to the ground electronic state, which converts the energy of the absorbed photon into vibrational energy. Such an energization scheme is depicted in figure 4.1 for formaldehyde, where the complete excitation/decomposition mechanism is . . . H2CO(S0) + hν → H2CO(S1) → H2CO*(S0) → H2 + CO . . . . . . (4.3) . . . Here, S0 and S1 represent the ground and first excited singlet states.
Тези доповідей конференцій з теми "Ground-state CO molecules"
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Castleman, A. Welford, C. R. Albertoni, K. Marti, D. E. Hunton, and R. G. Keesee. "Photodissociation dynamics of cluster anions." In International Laser Science Conference. Washington, D.C.: Optica Publishing Group, 1986. http://dx.doi.org/10.1364/ils.1986.jfc7.
Повний текст джерелаАнотація:
Studies of the dissociation dynamics of cluster ions provide insight into the process of energy disposal for mass-selected species. Detailed investigations of the photodissociation of the cluster anions ( SO 2 ) 2 − and CO 3 − ( H 2 O ) n ( 0 ≤ n ≤ 3 ) have been accomplished for mass-selected ion species using an intracavity dye laser pumped with an argon-ion laser. in the case of CO 3 − , the unhydrated parent ion is observed to have a bound electronic excited state through which absorption of a second photon proceeds to a repulsive state leading to the ejection of O-. There are two possible mechanisms for CO 3 - hydrate dissociation: one is a repulsive and the second a predissociative mechanism. In both, cluster dissociation is initiated by the same 2 A 1 ← 2 B 1 transition from the ground to a weakly bound excited state of the core ion and leads to the loss of all water molecules within the time of observation. In the photodissociation of CO 3 - , CO 3 - ( H 2 O ) 1 , 2 , 3 , and ( SO 2 ) 2 - considerable excess energy is partitioned into relative translation of the photoproducts. Through studies of energy release in ( SO 2 ) 2 - with photons of parallel and perpendicular polarization, evidence has been obtained that the lifetime of the complex preceding photodissociation is less than a rotational period. The implications of the findings are discussed in terms of phase space theory.
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Knaack, A., A. Offt, T. Mill, J. Walewski, and W. Schade. "Picosecond-LIF-Spectroscopy with NO in a High Pressure Cell." In Modern Spectroscopy of Solids, Liquids, and Gases. Washington, D.C.: Optica Publishing Group, 1995. http://dx.doi.org/10.1364/msslg.1995.sthb6.
Повний текст джерелаАнотація:
Flame radicals are fragments of molecules with high reactivity and control the process of combustion to a high degree. Therefore, the knowledge of accurate number densities of these species is very important, e.g. when modelling flames. Because of the relative large cross sections compared to other optical methods, laser-induced fluorescence (LIF) spectroscopy is one of the most sensitive techniques for accurate determination of concentrations and temperatures [1]. However, when LIF is applied for quantitative diagnostics at high pressures (10 bar >p> 1 bar) and high temperatures, which is typical for industrial combustions, several problems associated with the LIF-method itself appear, and limit the accuracy of the method. The laser excites an upper level population of the molecule or atom under investigation, which decays by spontaneous emission and radiationless by collisional induced processes (quenching). The latter one reduces the fluorescence yield considerably, two or three orders of magnitude are typical for atmospheric pressure. If the measurements are performed with a time resolution better than the quenching rates, the LIF-intensities can be used to extract absolute number densities. However, this requires a laser and a detection system with picosecond time resolution. Since important atomic radicals like O, C, N, H or diatomic molecules like NO, CO and OH can only be excited from the ground state via two- or one photon absorption in the spectral range between 200 and 300 nm [2] a powerful ultraviolet laser system is required in these experiments. However, the quantitative interpretation of the picosecond LIF-intensity measurements still needs accurate quenching rate data for the relevant pressures and temperatures and the species that are present in the combustion process. In the data analysis also systematic influences like photodissociation effects by the strong uv-laser pulses have to be considered. Therefore, in this paper improved quenching rate measurements of NO with NO, N2 and O2 for pressures up to p=10 bar, and photodissociation effects of NO are reported.