The Experts below are selected from a list of 44448 Experts worldwide ranked by ideXlab platform
Lidong Zhang - One of the best experts on this subject based on the ideXlab platform.
-
an experimental and theoretical study of toluene pyrolysis with tunable synchrotron vuv Photoionization and molecular beam mass spectrometry
Combustion and Flame, 2009Co-Authors: Taichang Zhang, Xin Hong, Lidong Zhang, Kuiwen Zhang, Fei Qi, Taohong Ye, Pinghui Zhao, Yiliang ChenAbstract:The pyrolysis of pyrrole (6.46% pyrrole in argon) has been performed with the tunable synchrotron vacuum ultraviolet (VUV) Photoionization and molecular-beam mass spectrometry (MBMS) technique. The experiment was carried out over the temperature range of 1260−1710 K at a pressure of 267 Pa. About 30 intermediates have been identified by near-threshold measurements of Photoionization mass spectra, and the corresponding mole fractions versus temperatures have been obtained. Moreover, the isomers of some pyrolysis products have been identified by the measurement of Photoionization efficiency spectrum. The major products are H2, C2H2, HCN, C3H4 (propyne), and C2H3N (acetonitrile). Meanwhile, some new intermediates, such as C4H4N (cyanoallyl radical) and C2H2N (cyanomethyl radical), have been determined. The major pyrolysis channels have been provided with the high-level ab initio G3B3 calculation and are well consistent with the experimental observation. The formation pathway of HCN via the cyclic carbene tau...
-
experimental study of a fuel rich premixed toluene flame at low pressure
Energy & Fuels, 2009Co-Authors: Lidong Zhang, Tao Yuan, Jing Wang, Zhenyu Tian, Bin YangAbstract:A low-pressure premixed toluene/O2/Ar flame with the equivalence ratio of 1.90 was investigated using tunable synchrotron vacuum ultraviolet (VUV) Photoionization mass spectrometry. Combustion intermediates up to C19H12 were identified by the measurements of the Photoionization mass spectrum and Photoionization efficiency spectrum. Mole fraction profiles of flame species were evaluated from the scan of burner position at photon energies near ionization thresholds. Furthermore, flame temperature was recorded by a Pt/Pt-13%Rh thermocouple. The comprehensive experimental data concerning the flame structure facilitate the discussion about the flame chemistry of toluene and other monocyclic aromatic fuels. Benzyl and benzene were found to be major primary intermediates of toluene degradation; and benzene is suggested to originate mainly from fuel degradation instead of radical recombination channels in fuel-rich monocyclic aromatic hydrocarbon flames. On the basis of the intermediate identification, comparison...
-
dissociative Photoionization mechanism of 1 8 dihydroxyanthraquinone an experimental and theoretical study
Journal of Physical Chemistry A, 2008Co-Authors: Yang Pan, Lidong Zhang, Huijun GuoAbstract:The Photoionization and dissociative Photoionization mechanism of 1,8-dihydroxyanthraquinone (1,8-DHAQ) have been investigated by infrared laser desorption/tunable synchrotron vacuum ultraviolet Photoionization mass spectrometry (IR LD/VUV PIMS) technique and theoretical calculations. Consecutive losses of two carbon monoxides and elimination of hydroxyl group are found to be the major fragmentation channels in low photon energy range. Photoionization efficiency (PIE) spectrum of 1,8-DHAQ was measured in the photon energy range of 8.2−15.0 eV. Adiabatic ionization energy (IE) of 1,8-DAHQ (M) and appearance energies (AEs) of the major fragments (M−CO)+, (M−C2O2)+, and (M−OH)+ are determined to be 8.54 ± 0.05, 10.8 ± 0.1, 11.0 ± 0.1, and 13.1 ± 0.1 eV, respectively, which are in fair agreement with calculated results. The B3LYP method with the 6-31+G(d) basis set was used to study fragmentation of 1,8-DHAQ. Theoretical calculations indicate that five lowest-energy isomers of 1,8-DHAQ cations can coexist by ...
-
pyrolysis of methyl tert butyl ether mtbe 1 experimental study with molecular beam mass spectrometry and tunable synchrotron vuv Photoionization
Journal of Physical Chemistry A, 2008Co-Authors: Taichang Zhang, Jing Wang, Tao Yuan, Xin Hong, Lidong ZhangAbstract:An experimental study of methyl tert-butyl ether (MTBE) pyrolysis (3.72% MTBE in argon) has been performed at low pressure (267 Pa) within the temperature range from 700 to 1420 K. The pyrolysis process was detected with the tunable synchrotron vacuum ultraviolet (VUV) Photoionization and molecular-beam mass spectrometry (MBMS). About thirty intermediates are identified from near-threshold measurements of Photoionization mass spectrum and Photoionization efficiency spectrum. Among them, H2, CO, CH4, CH3OH and C4H8 are the major pyrolysis products. The radicals such as methyl, methoxy, propargyl, allyl, C4H5 and C4H7 are detected. The isomers of pyrolysis products are identified as well, i.e., propyne and allene, 1,2,3-butatriene and vinylacetylene, isobutene and 1-butene, propanal and acetone. Furthermore, the mole fractions of the pyrolysis products have been evaluated under various temperatures. Meanwhile, the initial formation temperatures of different pyrolysis products can be obtained. This work is a...
Taichang Zhang - One of the best experts on this subject based on the ideXlab platform.
-
an experimental and theoretical study of toluene pyrolysis with tunable synchrotron vuv Photoionization and molecular beam mass spectrometry
Combustion and Flame, 2009Co-Authors: Taichang Zhang, Xin Hong, Lidong Zhang, Kuiwen Zhang, Fei Qi, Taohong Ye, Pinghui Zhao, Yiliang ChenAbstract:The pyrolysis of pyrrole (6.46% pyrrole in argon) has been performed with the tunable synchrotron vacuum ultraviolet (VUV) Photoionization and molecular-beam mass spectrometry (MBMS) technique. The experiment was carried out over the temperature range of 1260−1710 K at a pressure of 267 Pa. About 30 intermediates have been identified by near-threshold measurements of Photoionization mass spectra, and the corresponding mole fractions versus temperatures have been obtained. Moreover, the isomers of some pyrolysis products have been identified by the measurement of Photoionization efficiency spectrum. The major products are H2, C2H2, HCN, C3H4 (propyne), and C2H3N (acetonitrile). Meanwhile, some new intermediates, such as C4H4N (cyanoallyl radical) and C2H2N (cyanomethyl radical), have been determined. The major pyrolysis channels have been provided with the high-level ab initio G3B3 calculation and are well consistent with the experimental observation. The formation pathway of HCN via the cyclic carbene tau...
-
pyrolysis of methyl tert butyl ether mtbe 1 experimental study with molecular beam mass spectrometry and tunable synchrotron vuv Photoionization
Journal of Physical Chemistry A, 2008Co-Authors: Taichang Zhang, Jing Wang, Tao Yuan, Xin Hong, Lidong ZhangAbstract:An experimental study of methyl tert-butyl ether (MTBE) pyrolysis (3.72% MTBE in argon) has been performed at low pressure (267 Pa) within the temperature range from 700 to 1420 K. The pyrolysis process was detected with the tunable synchrotron vacuum ultraviolet (VUV) Photoionization and molecular-beam mass spectrometry (MBMS). About thirty intermediates are identified from near-threshold measurements of Photoionization mass spectrum and Photoionization efficiency spectrum. Among them, H2, CO, CH4, CH3OH and C4H8 are the major pyrolysis products. The radicals such as methyl, methoxy, propargyl, allyl, C4H5 and C4H7 are detected. The isomers of pyrolysis products are identified as well, i.e., propyne and allene, 1,2,3-butatriene and vinylacetylene, isobutene and 1-butene, propanal and acetone. Furthermore, the mole fractions of the pyrolysis products have been evaluated under various temperatures. Meanwhile, the initial formation temperatures of different pyrolysis products can be obtained. This work is a...
Gang Zhao - One of the best experts on this subject based on the ideXlab platform.
-
Photoionization dynamics of Rydberg atom in a space-dependent magnetic field
'Springer Science and Business Media LLC', 2021Co-Authors: De-hua Wang, Gang Zhao, Zhao-peng Sun, Shu-fang ZhangAbstract:The Photoionization dynamics of Rydberg hydrogen atom in a space-dependent magnetic field has been studied for the first time. Because of the non-uniform magnetic field, this system is non-integrable, and its dynamics becomes more complex than that in a uniform magnetic field. The exact analytic electron wave function can not be obtained by solving the Schrödinger equation quantum mechanically, instead, it can be constructed within the framework of the semiclassical EBKM scheme, which gives the correspondence between the quantum wave function and a family of classical electron trajectories. The observed oscillatory structures in the electron probability density distributions on the detector plane can be understood by considering the accumulated phase among different classical trajectories by which the electron moves from the atom to the detector. The calculation results suggest that the patterns of the Photoionization microscopy can be modulated by changing the scaled energy, the position of the detector plane and the initial state wave function. Once the Photoionization microscopy image on the detector has been measured in the experiment, it can be used to recover the angular distribution of the electron wave function. Our work provides a convincing semiclassical interpretation of the Photoionization microscopy image and the underlying classical dynamics, and may guide future experimental study on the Photoionization microscopy of the Rydberg atom in the non-uniform magnetic fields
-
modeling non local thermodynamic equilibrium plasma using the flexible atomic code data
Publications of the Astronomical Society of Japan, 2015Co-Authors: Bo Han, Feilu Wang, David Salzmann, Gang ZhaoAbstract:We developed a new code, Radiative-Collisional code based on FAC (abbreviated RCF), which is used to simulate steady-state plasmas under non local thermodynamic equilibrium condition, especially Photoionization dominated plasmas. RCF takes almost all of the radiative and collisional atomic processes into rate equation to interpret the plasmas systematically. The Flexible Atomic Code (FAC) supplies all the atomic data RCF needed, which insures calculating completeness and consistency of atomic data. With four input parameters relating to the radiation source and target plasma, RCF calculates the population of levels and charge states, as well as potentially emission spectrum. In preliminary application [1], RCF successfully reproduces the results of a Photoionization experiment at Sandia National Laboratory Z-facility [2] with reliable atomic data. The effects of the most important atomic processes on the charge state distribution are also discussed. In the calculations of RCF, the charge state distribution of this experiment is a composite result of different atomic processes. The external field dominates the ionizations in the plasma by Photoionization directly and photoexcitation plus autoionization indirectly. The transitions within any given single charge state can significantly affect the charge state distribution, and one of the interesting results of our computations is the role played by collisional excitation in this experiment, in which it reduces the total ionization rate by competing with Photoionization and photoexcitation.
-
modeling non local thermodynamic equilibrium plasma using the flexible atomic code data
arXiv: Atomic Physics, 2015Co-Authors: Bo Han, Feilu Wang, David Salzmann, Gang ZhaoAbstract:We present a new code, RCF("Radiative-Collisional code based on FAC"), which is used to simulate steady-state plasmas under non local thermodynamic equilibrium condition, especially photoinization dominated plasmas. RCF takes almost all of the radiative and collisional atomic processes into rate equation to interpret the plasmas systematically. The Flexible Atomic Code (FAC) supplies all the atomic data RCF needed, which insures calculating completeness and consistency of atomic data. With four input parameters relating to the radiation source and target plasma, RCF calculates the population of levels and charge states, as well as potentially emission spectrum. In preliminary application, RCF successfully reproduces the results of a Photoionization experiment with reliable atomic data. The effects of the most important atomic processes on the charge state distribution are also discussed.
L E Brus - One of the best experts on this subject based on the ideXlab platform.
-
surface states in the Photoionization of high quality cdse core shell nanocrystals
ACS Nano, 2009Co-Authors: Michael L Steigerwald, L E BrusAbstract:We use electric force microscopy (EFM) to study single nanocrystal Photoionization in two classes of high-quality nanocrystals whose exciton luminescence quantum yields approach unity in solution. The CdSe/CdS/ZnS core/shell nanocrystals do not photoionize, while the CdSe/CdS nanocrystals do show substantial Photoionization. This verifies the theoretical prediction that the ZnS shell confines the excited electron within the nanocrystal. Despite the high luminescence quantum yield, Photoionization varies substantially among the CdSe/CdS nanocrystals. We have studied the nanocrystal Photoionization with both UV (396 nm) and green (532 nm) light, and we have found that the magnitude of the charge due to Photoionization per absorbed photon is greater for UV excitation than for green excitation. A fraction of the Photoionization occurs directly via a “hot electron” process, using trap states that are either on the particle surface, within the ligand sphere, or within the silicon oxide layer. This must occur wi...
-
imaging the Photoionization of individual cdse cds core shell nanocrystals on n and p type silicon substrates with thin oxides
Journal of Physical Chemistry B, 2004Co-Authors: Oksana Cherniavskaya, Liwei Chen, L E BrusAbstract:The low-intensity Photoionization of individual semiconductor nanocrystals, at 23 °C in dry nitrogen, is time-resolved over many hours for both S (532-nm excitation) and P (395-nm excitation) nanocrystal excited states using electrostatic force microscopy. Over 7000 calibrated charge measurements have been made on 14- and 21-A-thick oxide layers. Photoexcited electrons tunnel across the oxide into the silicon, and multiple charges can build up on individual nanocrystals at intensities of only 0.1−0.01 W/cm2. The silicon dopant type influences the net nanocrystal charging via the interfacial band bending; P-type subtrates show a faster nanocrystal reneutralization rate due to their higher interfacial electron concentration. There is a huge range of photoionzation behavior for individual nanocrystals. This behavior is different for 395- and 532-nm excitation in the same nanocrystal. This individuality seems in part to reflect tunneling through spatially localized defect states in the oxide. The line widths ...
Yiliang Chen - One of the best experts on this subject based on the ideXlab platform.
-
an experimental and theoretical study of toluene pyrolysis with tunable synchrotron vuv Photoionization and molecular beam mass spectrometry
Combustion and Flame, 2009Co-Authors: Taichang Zhang, Xin Hong, Lidong Zhang, Kuiwen Zhang, Fei Qi, Taohong Ye, Pinghui Zhao, Yiliang ChenAbstract:The pyrolysis of pyrrole (6.46% pyrrole in argon) has been performed with the tunable synchrotron vacuum ultraviolet (VUV) Photoionization and molecular-beam mass spectrometry (MBMS) technique. The experiment was carried out over the temperature range of 1260−1710 K at a pressure of 267 Pa. About 30 intermediates have been identified by near-threshold measurements of Photoionization mass spectra, and the corresponding mole fractions versus temperatures have been obtained. Moreover, the isomers of some pyrolysis products have been identified by the measurement of Photoionization efficiency spectrum. The major products are H2, C2H2, HCN, C3H4 (propyne), and C2H3N (acetonitrile). Meanwhile, some new intermediates, such as C4H4N (cyanoallyl radical) and C2H2N (cyanomethyl radical), have been determined. The major pyrolysis channels have been provided with the high-level ab initio G3B3 calculation and are well consistent with the experimental observation. The formation pathway of HCN via the cyclic carbene tau...
