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81.
Density functional theory is used to construct an interaction model for H atoms with Cl over Au(111). Single-adsorbate Eley-Rideal reactions are investigated with quantum and quasiclassical methods. The reaction cross sections, amounting to 2-3 A(2), are much larger than for HD recombinations on metals. This can be traced to the adsorbed Cl being relatively far above the surface, the H-Cl interaction prevailing over the H-substrate attraction for a sizable range of impact parameters. 相似文献
82.
The understanding of complex phenomena, the experimental validation of calculation codes, and the construction of data bases in fluid mechanics require the development of non-intrusive experimental techniques. The laser-induced fluorescence of a gaseous molecule seeded into a gas flow can be related to the flowfield thermodynamic parameters, such as pressure and temperature. An experimental method is described, that allows the removal of the temperature dependence of the fluorescence signal. A narrow-bandwidth single-line laser is tuned to the center of an absorption line, whose temperature dependence of the Boltzmann fraction can be neglected. The experimental set-up requires a single-line dye laser and a high resolution spectral analysis device.The accuracy of the method, checked in a static vessel, appears to be better than 5%. The method has been successfully tested with a supersonic jet issuing from an underexpanded nozzle.The experimental results have been compared to those of an Euler calculation. A mean difference of 14% has been observed, but a major part of this can be attributed to the difference between inviscid and real gas calculation.List of Symbols
A
21
spontaneous emission Einstein coefficient
-
B
v
rotational energy of the J level for the v vibrational level
-
B
e
first order approximation of B
v
-
c
velocity of light
-
C
opt
optical constant
-
E(v)
vibrational energy of the v level
-
f
1
Boltzmann fraction
-
FCF
i
Franck-Condon factor of the ith line
-
f
v
vibrational fraction
-
tf
r
rotational fraction
-
g
efficient spectral power density
-
h
Planck constant
-
I
2
X
iodine molecule in the X state
-
I
2
B
iodine molecule in the B state
- [I
2
X]
molecular concentration of I
2
X
- [I
2
B]
molecular concentration of I
2
B
-
I
i
relative intensity of the ith absorption line
-
J
rotational level of the fundamental state
-
J
rotational level of the excited state
-
k
Boltzmann constant
-
k
c
collisional broadening coefficient
-
m
iodine molecular mass
-
n
0
initial concentration of iodine in the absorbing state
-
P
pressure
-
P
laser
laser power
-
P
l(v)
laser power spectral density
-
P
sl2
iodine vapor pressure
-
Q
quenching rate
-
Q
v
vibrational partition function
-
T
temperature
-
v
vibrational level of the fundamental state
-
v
vibrational level of the excited state
-
V
c
collection volume
-
X
l
2
iodine molar fraction
-
wave length
-
v
D
Doppler linewidth, at half maximum
-
v
c
collisional linewidth at half maximum
-
Vl
laser frequency
-
(v)
Dirac function
-
v
i
spectral location of a line, referenced to the laser frequency 相似文献
83.
Delignières D Torre K Lemoine L 《Nonlinear dynamics, psychology, and life sciences》2005,9(4):435-461
A number of recent research works tried to apply fractal methods to psychological or behavioral variables. Quite often, nevertheless, the use of fractal analyses remains rudimentary, and the goal of researchers seems limited to evidencing the presence of long- range correlation in data sets. This article presents some recent developments in monofractals theory, and some related methodological refinements. We also discuss a number of specific issues related to the application of fractal methods in psychological and behavioral research. Finally, we consider the potential use of such approach for a renewal of classical issues in psychology and behavioral science. 相似文献
84.
Norio Saito Pierric Lemoine Noée Dumait Maria Amela-Cortes Serge Paofai Thierry Roisnel Vivian Nassif Fabien Grasset Yoshiki Wada Naoki Ohashi Stéphane Cordier 《Journal of Cluster Science》2017,28(2):773-798
We report here the synthesis, the crystal structure and the luminescent properties of the new cluster compounds Cs2Mo6Cl14·H2O and Cs2Mo6Br14·H2O. Single-crystal X-ray diffraction performed on Cs2Mo6Cl14·H2O indicates that the compound crystallizes in the monoclinic space group C2/c with refined cell parameters a = 19.578 Å, b = 15.151 Å, c = 9.347 Å, and β = 115.64°. The structure can be described from discrete \(\left[ {{\text{Mo}}_{ 6} {\text{Cl}}^{\text{i}}_{ 8} {\text{Cl}}^{\text{a}}_{ 6} } \right]^{ 2- }\) anionic cluster units arranged in a “A–A’–A–A’” pseudo prismatic stacking parallel to (b, c) plane with both Cs+ cations and water molecules located between the layers. Moreover, the centric character of the trigonal structure of Cs2Mo6Cl14 was also studied by combination of single-crystal X-ray diffraction and both X-ray and neutron powder diffraction. The results suggest an important influence of the sample preparation on the symmetry of the crystal structure. The crystal structure relationship between the \(\left[ {{\text{Mo}}_{ 6} {\text{Cl}}^{\text{i}}_{ 8} {\text{Cl}}^{\text{a}}_{ 6} } \right]^{ 2- }\) anionic cluster unit arrangements in Cs2Mo6Cl14 and Cs2Mo6Cl14·H2O is discussed. Finally, the characterization of the luminescent properties of Cs2Mo6X14 and Cs2Mo6X14·H2O (X = Cl, Br) indicates that emission profile is comparable regardless existence of water molecule in the crystal structure. 相似文献
85.
Valdés A Prosmiti R Villarreal P Delgado-Barrio G Lemoine D Lepetit B 《The Journal of chemical physics》2007,126(24):244314
Three-dimensional quantum mechanical calculations on the vibrational predissociation dynamics of HeI2 B state complex are performed using a potential energy surface accurately fitted to unrestricted open-shell coupled cluster ab initio data, further enabling extrapolation for large I2 bond lengths. A Lanczos iterative method with an optimized complex absorbing potential is used to determine energies and lifetimes of the vibrationally predissociating He,I2(B,v') complex for v'相似文献
86.
O. Rousière D. Lemoine H. Folliot S. Hinooda R. Granger 《The European Physical Journal B - Condensed Matter and Complex Systems》1999,11(3):491-496
Strong oscillations on capacitance and conductance have been observed in p-type Hg0.8Zn0.2Te metal-insulator-semiconductor structures, made by using a recent process for the interface passivation. This behaviour is
attributed to a two-dimensional electron gas in the n-inversion layer and the variation of the conductance maximums with temperature
indicates that the dominant perpendicular transport mechanism for electrons is an incoherent two-step tunnelling through deep
levels in the gap. Three models have been used to describe the quantum confinement: the simple variational method, the triangular
potential approximation and the propagation matrix method. The later approach takes into account the non parabolicity of the
conduction band structure and uses a finite height barrier at the insulator-semiconductor interface. A very good agreement
between experimental and calculated values for the two lowest subband energy is obtained.
Received 9 February 1999 相似文献
87.
F. Bentefrit P. Lemoine D. Nguyen‐Huy G. Morgant B. Viossat 《Acta Crystallographica. Section C, Structural Chemistry》2003,59(8):m331-m333
The asymmetric unit of the title compound, [Ni(C11H16ClN5)2]Cl2·C3H7NO, contains one monomeric nickel(II) complex cation, two Cl− anions and one dimethylformamide solvent molecule. The Ni atom is coordinated to each of two 1‐(p‐chlorophenyl)‐5‐isopropylbiguanide (proguanil) ligands via two N atoms. The complex exhibits a square‐planar coordination, with the Ni atom lying 0.021 (2) Å out of the basal plane. The crystal packing is characterized by several hydrogen bonds. 相似文献
88.
J. Magan D. Lupo W. Praß U. Scheunemann P. Lemoine W. Blau M. Hogan 《Macromolecular Symposia》1991,46(1):253-257
Photoablation of several Langmuir-Blodgett (LB) films on Silicon substrates was performed at the excimer laser wavelength of 248 nm. This is a fast, solvent-free, one-step method for structuring thin organic films. Structures were produced both by projection of a mask and also using direct writing of the laser beam, yielding feature sizes on the order of microns. Spectral analysis of the remaining material showed no change compared to the unexposed material, suggesting that no degradation has occurred. This technique appears to be viable for use in the lithography of LB films. 相似文献
89.
The TiNiSi-type structure, antiferromagnetic ordering and divalent state of europium in EuPdSn have been confirmed by neutron powder diffraction. The Néel temperature is 16.2(3) K. The magnetic diffraction peaks can be indexed with a propagation vector k = [0, 0.217, q(z)] (q(z) ≤ 0.02) at 13.2 K, and k = [0, 0.276, 0] at 3.6 K, indicating an incommensurate antiferromagnetic structure at both temperatures. At 13.2 K, the best refinement is obtained with a sinusoidally modulated magnetic structure and europium magnetic moments oriented in the (a,b) plane with an azimuthal angle ? of 66(4)°relative to the a-axis. By 3.6 K, the magnetic structure of EuPdSn has transformed to an (a,b) planar helimagnetic structure (a 'flat spiral'). 相似文献
90.
B Bellina I Compagnon L MacAleese F Chirot J Lemoine P Maître M Broyer R Antoine A Kulesza R Mitrić V Bonačić-Koutecký P Dugourd 《Physical chemistry chemical physics : PCCP》2012,14(32):11433-11440
Transition metal-ion complexation is essential to the function and structural stability of many proteins. We studied silver complexation with the octarepeat motif ProHisGlyGlyGlyTrpGlyGln of the prion protein, which shows competitive sites for metal chelation including amide, indole and imidazole groups. This octapeptide is known as a favourable transition metal binding site in prion protein. We used ion mobility spectrometry (IMS), infrared multiple photon dissociation (IRMPD) spectroscopy and density functional theory calculations (DFT) to identify the binding motifs of a silver cation on HisGlyGlyGlyTrp peptide as well as on peptide subsequences. Ultra-violet photodissociation (UVPD) and collision induced dissociation mass spectrometry together with the time-dependent density functional method was then exploited to study the influence of binding sites on optical properties and on the ground and excited states reactivity of the peptide. We show that the metal cation is bound to the π-system of the indole group and a nitrogen atom of the imidazole group and that charge transfers from the indole group to the silver cation occur in excited electronic states. 相似文献