The Experts below are selected from a list of 207 Experts worldwide ranked by ideXlab platform
Wonho Choe - One of the best experts on this subject based on the ideXlab platform.
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Temperature measurement of an atmospheric pressure arc discharge plasma jet using the diatomic CN (BΣ+2-XΣ+2, violet system) Molecular Spectra
Journal of Applied Physics, 2009Co-Authors: Youn Moon, Dong-yung Kim, B. Gweon, Wonho ChoeAbstract:The CN (BΣ+2-XΣ+2) Molecular emission spectrum is used to measure both the vibrational and rotational temperatures in atmospheric pressure arc jet discharges. The vibrational and rotational temperature effects on the synthetic diatomic Molecular Spectra were investigated from the (v′,v″)=(0,0) band to the (5,5) band. The temperatures obtained from the synthetic Spectra compared with the experimental result of a low-frequency arc discharge show a vibrational temperature of (4250–5010)K and a rotational temperature of (3760–3980)K for the input power in the range of (80–280)W. As the (0,0) band is isolated from other vibrational transition bands, determination of the rotational temperature is possible based only on the (0,0) band, which simplifies the temperature measurement. From the result, it was found that the CN Molecular spectrum can be used as a thermometer for atmospheric pressure plasmas containing carbon and nitrogen.
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a comparative study of rotational temperatures using diatomic oh o2 and n2 Molecular Spectra emitted from atmospheric plasmas
Spectrochimica Acta Part B: Atomic Spectroscopy, 2003Co-Authors: Se Youn Moon, Wonho ChoeAbstract:From the application point of view, gas temperature is one of the most important parameters for atmospheric plasmas. Based on the fact that the gas temperature is closely related with the rotational temperature of an atmospheric plasma, a spectroscopic method of measuring the rotational temperature is described in this work by analyzing OH, O and N Molecular Spectra emitted from the atmospheric plasma in ambient air. The OH and N Molecular Spectra q q 22 2 are emitted because of the oxygen, hydrogen and nitrogen atoms existing in the ambient air. The O diatomic 2 Molecular spectrum is emitted from the oxygen plasma that is frequently produced for atmospheric plasma applications. In order to utilize a spectrometer with modest Spectral resolution, a synthetic diatomic Molecular spectrum was compared with the experimentally obtained spectrum. The rotational temperatures determined by the above three different Molecular Spectra are in good agreement within 2.4% error. In the case of a plasma with low gas temperature, the temperature measured by a thermocouple was compared to verify the accuracy of the spectroscopic method, and the results show excellent agreement. From the study, it was found that an appropriate diatomic Molecular species can be chosen to be used as a thermometer depending on experimental circumstances. 2002 Elsevier Science B.V. All rights reserved.
Tilman Pfau - One of the best experts on this subject based on the ideXlab platform.
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From Molecular Spectra to a density shift in dense Rydberg gases.
Nature communications, 2014Co-Authors: Anita Gaj, Alexander T. Krupp, Jonathan B. Balewski, Robert Löw, Sebastian Hofferberth, Tilman PfauAbstract:In Rydberg atoms, at least one electron is excited to a state with a high principal quantum number. In an ultracold environment, this low-energy electron can scatter off a ground state atom allowing for the formation of a Rydberg molecule consisting of one Rydberg atom and several ground state atoms. Here we investigate those Rydberg molecules created by photoassociation for the spherically symmetric S-states. A step by step increase of the principal quantum number up to n=111 enables us to go beyond the previously observed dimer and trimer states up to a molecule, where four ground state atoms are bound by one Rydberg atom. The increase of bound atoms and the decreasing binding potential per atom with principal quantum number results finally in an overlap of Spectral lines. The associated density-dependent line broadening sets a fundamental limit, for example, for the optical thickness per blockade volume in Rydberg quantum optics experiments.
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from Molecular Spectra to a density shift in dense rydberg gases
Nature Communications, 2014Co-Authors: Anita Gaj, Alexander T. Krupp, Jonathan B. Balewski, Robert Löw, Sebastian Hofferberth, Tilman PfauAbstract:Ultracold Rydberg atoms — atoms with highly excited electrons — can form molecules with ground state atoms. By tuning the principal quantum number of the Rydberg state, Gaj et al. study the transition from resolvable Molecular lines to the mean shift regime, where indistinguishable lines form a band.
Ralf Steudel - One of the best experts on this subject based on the ideXlab platform.
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Molecular Spectra of Sulfur Molecules and Solid Sulfur Allotropes
Topics in Current Chemistry, 1Co-Authors: Bodo Eckert, Ralf SteudelAbstract:Molecular spectroscopy is one of the most important means to characterize the various species in solid, liquid and gaseous elemental sulfur. In this chapter the vibrational, UV-Vis and mass Spectra of sulfur molecules with between 2 and 20 atoms are critically reviewed together with the Spectra of liquid sulfur and of solid allotropes including polymeric and high-pressure phases. In particular, low temperature Raman spectroscopy is a suitable technique to identify single species in mixtures. In mass Spectra cluster cations with up to 56 atoms have been observed but fragmentation processes cause serious difficulties. The UV-Vis Spectra of S4 are reassigned. The modern XANES spectroscopy has just started to be applied to sulfur allotropes and other sulfur compounds.
Anita Gaj - One of the best experts on this subject based on the ideXlab platform.
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From Molecular Spectra to a density shift in dense Rydberg gases.
Nature communications, 2014Co-Authors: Anita Gaj, Alexander T. Krupp, Jonathan B. Balewski, Robert Löw, Sebastian Hofferberth, Tilman PfauAbstract:In Rydberg atoms, at least one electron is excited to a state with a high principal quantum number. In an ultracold environment, this low-energy electron can scatter off a ground state atom allowing for the formation of a Rydberg molecule consisting of one Rydberg atom and several ground state atoms. Here we investigate those Rydberg molecules created by photoassociation for the spherically symmetric S-states. A step by step increase of the principal quantum number up to n=111 enables us to go beyond the previously observed dimer and trimer states up to a molecule, where four ground state atoms are bound by one Rydberg atom. The increase of bound atoms and the decreasing binding potential per atom with principal quantum number results finally in an overlap of Spectral lines. The associated density-dependent line broadening sets a fundamental limit, for example, for the optical thickness per blockade volume in Rydberg quantum optics experiments.
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from Molecular Spectra to a density shift in dense rydberg gases
Nature Communications, 2014Co-Authors: Anita Gaj, Alexander T. Krupp, Jonathan B. Balewski, Robert Löw, Sebastian Hofferberth, Tilman PfauAbstract:Ultracold Rydberg atoms — atoms with highly excited electrons — can form molecules with ground state atoms. By tuning the principal quantum number of the Rydberg state, Gaj et al. study the transition from resolvable Molecular lines to the mean shift regime, where indistinguishable lines form a band.
Bodo Eckert - One of the best experts on this subject based on the ideXlab platform.
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Molecular Spectra of Sulfur Molecules and Solid Sulfur Allotropes
Topics in Current Chemistry, 1Co-Authors: Bodo Eckert, Ralf SteudelAbstract:Molecular spectroscopy is one of the most important means to characterize the various species in solid, liquid and gaseous elemental sulfur. In this chapter the vibrational, UV-Vis and mass Spectra of sulfur molecules with between 2 and 20 atoms are critically reviewed together with the Spectra of liquid sulfur and of solid allotropes including polymeric and high-pressure phases. In particular, low temperature Raman spectroscopy is a suitable technique to identify single species in mixtures. In mass Spectra cluster cations with up to 56 atoms have been observed but fragmentation processes cause serious difficulties. The UV-Vis Spectra of S4 are reassigned. The modern XANES spectroscopy has just started to be applied to sulfur allotropes and other sulfur compounds.