共查询到20条相似文献,搜索用时 741 毫秒
1.
A. M. Orlov I. O. Yavtushenko M. V. Churilov 《Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques》2010,4(5):831-835
The adsorption and kinetic processes of the formation of gas bubbles passivating the surface during polarization of copper
and graphite electrodes in 1% aqueous solution of sulfuric acid have been investigated. Three stages of the process related
to the recharging of the double electric layer—adsorption accumulation of the gas escaping from the surface, the critical
nucleation of the gas bubbles, and their subsequent growth—have been revealed, distinguished, and quantitatively estimated.
It has been shown that potential leveling at the steady-state value specified by the Tafel equation is unambiguously associated
with achievement of the limiting surface area screened by the gas bubbles for each particular current density. The surface
diffusion constants D
H = (1.5–4.4) × 10−4 and (0.1–3.8) × 10−5 cm2/s of hydrogen on copper and graphite, respectively, and D
O = (1.8–4.5) × 10−7 cm2/s of oxygen on graphite during the motion toward the drain (the gas bubbles) have been calculated. 相似文献
2.
F–B–S tri-doped titanium dioxide thin films on common glass were prepared by a modified sol–gel method, in which tetrabutyl
titanate (Ti(OC4H9)4) was chosen as the precursor and boric acid (H3BO3), sodium fluoride (NaF), and thiourea (N2H4CS) were employed as boron, fluorine, and sulfur sources, respectively. The microstructure and optical property were characterized
by X-ray diffraction, high-resolution field emission scanning electron microscopy, N2 adsorption–desorption isotherms, photoluminescence spectrum, and UV–Vis diffraction reflectance spectroscopy. The photocatalytic
performances were evaluated by decomposition of organic dyes in solution. The experimental results revealed that the F–B–S
tri-doped TiO2 thin film was composed of uniform round-like nano-particles with the size range of 5–8 nm. F–B–S tri-doping not only significantly promoted the UV-induced photodecomposition activities of TiO2 films but also extended the optical response of TiO2 red shift to visible light region, herein improving the visible light-induced degradation of organic dyes. The improvement
mechanism by F–B–S tri-doping was also discussed. 相似文献
3.
Eu(III)-9-acridinecarboxylate (9-ACA) complex was synthesized and characterized by elemental analysis, conductivity measurement,
IR spectroscopy, thermal analysis, mass spectroscopy, 1H-NMR, fluorescence and ultraviolet spectra. The results indicated that the composition of this complex is [Eu(III)-(9-ACA)2(NCS)(C2H5OH)2] 2.5 H2O and the oxygen of the carbonyl group coordinated to Eu(III). The interaction between the complex with nucleotides guanosine
5′- monophosphate (5′-GMP), adenosine 5′-diphosphates (5′-ADP), inosine (5′-IMP) and CT-DNA was studied by fluorescence spectroscopy.
The fluorescence intensity of Eu(III)-9-acridinecarboxylate complex was enhanced with the addition of CT-DNA. The effect of
pH values on the fluorescence intensity of Eu(III) complex was investigated. Under experimental conditions, the linear range
was 9–50 ng mL−1 for calf thymus DNA (CT- DNA) and the corresponding detection limit was 5 ng mL−1. The results showed that Eu(III)-(9-ACA)2 complex binds to CT-DNA with stability constant of 2.41 × 104 M . 相似文献
4.
We discuss possible directions for searching for prospective materials based on low-valency uranium (III–V) as detection media
for hard electromagnetic radiation.
We have studied the processes of formation of tetravalent and pentavalent uranium complexes from UO2(NO3)3·6H2O and UO2Cl2·H2O in DMF and with addition of CCl4, including when the systems are exposed to radiation in the visible range (400–450 nm). In the first case (UO2(NO3)3·6H2O solutions in DMF), upon irradiation we observe stable complexes of pentavalent uranium, and when CCl4 is added to the solution we observe complexes of tetravalent uranium. In the system UO2Cl2·3H2O in DMF, we do not observe the appearance of new forms of uranium; but when CCl4 is added, then complexes of tetravalent uranium are formed.
__________
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 74, No. 2, pp. 184–187, March–April, 2007. 相似文献
5.
O. M. Bordun 《Journal of Applied Spectroscopy》1997,64(4):476-479
This is a study of IR reflection spectra of systems of a thin Bi4X3O12(X=Si, Ge) film and a substrate of fused quartz v-SiO2 in the range 400–1600 cm−1 at T=295 K. Bands assigned to Bi4X3O12 are interpreted. It is found that single-photon processes are exhibited in the range 400–800 cm−1, while biphonon processes, in the range 800–1600 cm−1.
I. Franko State University of Lvov, 50 Dragomanov St., 290005, Lvov, Ukraine. Translated from Zhurnal Prikladnoi Spektroskopii,
Vol. 64, No. 4, pp. 494–498, July–August, 1997. 相似文献
6.
The results of investigation of the spectra of 2-butanol in CCl4, pure 2-butanol, and a 2-butanol— water mixture in the region of the second overtone of the stretching O—H vibration are
presented. The assignment of the bands of the overtones is performed. The role of various associates in the processes of stratification
in the 2-butanol—water system is discussed.
__________
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 72, No. 6, pp. 837–839, November–December, 2005. 相似文献
7.
T. Sato T. Majima Kenro Hashimoto Kouhei Hashimoto Y. Zama J. Matsumoto H. Shiromaru K. Okuno H. Tanuma T. Azuma 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2011,63(2):189-194
Microhydrated methylene blue cations,
MB+(H2O)
n
, are produced in an
electrospray ion source and their size-distributions are measured as a function of the
source temperature. A series of
MB+(H2O)
n
ions is observed up to
n ≃ 60. A striking feature observed in the mass spectra is that the
series of hydrated ions starts at n = 4; intensities of
n = 1–3 are extremely suppressed. The absence of
n = 1–3 ions is well explained by the energetics concerning evaporation
processes of water molecules, based on stable structures and the binding energies of
MB+(H2O)
n
ions calculated by DFT
calculations up to n = 5.
MB+(H2O)
n
ions for
n > 4 evaporate a single water molecule
sequentially, while MB+(H2O)4 tends to fragment into
MB+ and (H2O)4 rather than
MB+(H2O)3 and an H2O molecule. We have
observed a clear magic peak at n = 24, which strongly suggests that the
MB+(H2O)24 ion is formed by attaching a neutral
(H2O)20 cage onto an MB+(H2O)4
ion. 相似文献
8.
The IR spectra of glasses of the ZnO—SrO—B2O3 system with constant additions of PbO, Al2O3, and Li2O (20 mol. % in sum) were studied. It is established that on replacement of B2O3 by ZnO, the structure of the glasses is characterized by the presence of groupings with the bridge bonds BIII— O—BIII, BIII—O—BIV, BIV—O—BIV and end groups BIII— O−; ZnO practically exerts no influence on the coordination transition [BO3] → [BO4]. At a high content of ZnO, zinc ions are present in both a six-and a four-coordinated state.
__________
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 72, No. 6, pp. 778–781, November–December, 2005. 相似文献
9.
The infrared and Raman spectra of NaNi2OH(H2O)(MoO4)2 and NaZn2OH (H2O)(MoO4)2 and their partially deuterated analogues are recorded and analysed on the basis of vibrations of MoO
4
2−
tetrahedra and H2O molecules. The MoO
4
2−
groups are found to be more distorted in NaNi2OH(H2O)(MoO4)2 than in the other compound. Bands indicating the presence of H3O+ ions are not observed in NaZn2OH(H2O)(MoO4)2 ruling out the possibility of the formulation of NaZn2OHO(MoO3OH)2. Hydrogen bonds of medium strength are present in both the compounds. 相似文献
10.
A comparative study is made of the influence of sulfide passivation in an aqueous Na2S·9H2O solution on the photoconversion parameters of solar radiation in Au-GaAs barrier structures as a function of the character
of the microrelief and the pretreatment of the GaAs surface. A quasigrating and a dendritic surface microrelief were produced
by anisotropic chemical etching. It is shown that this type of GaAs surface treatment is potentially useful for enhancing
the efficiency of a photovoltaic cell stored for several years. A possible mechanism is discussed for the processes leading
to changes in the structure parameters.
Zh. Tekh. Fiz. 69, 132–134 (June 1999) 相似文献
11.
I. I. Polovinko S. V. Rykhlyuk V. B. Koman I. D. Karbovnyk 《Journal of Applied Spectroscopy》2009,76(1):116-120
We propose a new method for obtaining K2Co
x
Ni1–x
(SO4)2⋅6H2O (x = 0, 0.4, 0.8, 1) crystals, involving the use of the chlorides (CoCl2⋅6H2O and NiCl2⋅6H2O) in an aqueous solution instead of the widely used sulfates. We have studied the transmission spectra of the grown single
crystals in the range λ = 200–900 nm and the IR reflectance spectra in the 2.5–20 μm region. We have observed a change in
the position and intensity of the absorption bands as a function of the composition of the crystals. Based on the Tanabe–Sugano
diagrams, we determined the crystal field splitting (Dq) and its dependence on the nickel concentration.
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 76, No. 1, pp. 126–130, January–February, 2009. 相似文献
12.
P. Patzner A.V. Osipov P. Hess 《Applied Physics A: Materials Science & Processing》2006,85(2):145-150
The growth of ultra-thin (<2 nm) silicon-oxide films was investigated on Si(100):H, Si(111):H, and a-Si:H surfaces in a pure water atmosphere (0.1–10 Pa) at low temperatures of 30–250 °C. Oxidation was induced photochemically by pulsed F2-laser radiation at 157 nm. The thickness and composition of the growing oxide films were monitored in real time by spectroscopic ellipsometry in the photon energy range of 1.15–4.75 eV. The mechanism of laser-induced silicon oxidation in a H2O atmosphere is shown to differ fundamentally from the classical Deal–Grove mechanism of thermal oxidation at 900–1200 °C, as well as from the photoinduced low-temperature oxidation in an O2 atmosphere. In particular, the film thickness essentially does not depend on temperature below 250 °C. A kinetic model is developed for low-temperature silicon oxidation in a H2O atmosphere. According to this model, the growth is limited at small thicknesses by the oxidation reaction and at larger thicknesses by reactions of the diffusing oxidizing species in the oxide layer. Very good agreement is established between this kinetic model and the ellipsometric measurements and the temperature and pressure dependence of the water oxidation process. PACS 82.65.+r; 07.60.Fs; 81.65.Mq; 82.50.Hp 相似文献
13.
The complex [Tb0.1Gd0.9(TPTZ)(H2O)6]Cl3·3H2O was prepared through the reaction of 2,4,6-tris-(2-pyridyl)-1,3,5-triazine (TPTZ) with TbCl3:GdCl3 (0.1:0.9) in absolute ethanol at room temperature. Single crystal X-ray diffraction revealed that the metal atom is nine-coordinated
with three nitrogen atoms from one TPTZ ligand and six oxygen atoms from six water molecules. The complex emits intense green
fluorescence under ultraviolet light. The luminescence peaks correspond to the characteristic emission 5D4→7FJ (J = 3–6) transitions of the Tb3+ ion. 相似文献
14.
A. K. Shuaibov 《Journal of Applied Spectroscopy》1999,66(2):256-262
Survey emission spectra in the region of 190–600 nm and time and service-life characteristics of a transverse nanosecond discharge
in He/Ar/CF2Cl2(CCl4) mixtures at a pressure of 10–100 kPa are investigated. In the emission spectra, excited products of the decomposition of
freons—C2(A−X), CN(B−X), Cl
2
*
, C*, Cl*, and Cl+*— and the emission of ArF at λ=193 nm are revealed. The emissions of Cl
2
*
at λ=258 nm and ArF at λ=193 nm were the most intense. The discharge in the He/Ar/CF2Cl2 mixture is a multiwave emission source with λ=258 nm Cl
2
*
193 nm ArF, and probably, 175 nm Arcl. It is of interest for applications in UV-VUV-range pulse photometry. The duration
of the emission on Cl
2
*
, ArF, ArI, ClI, and ClII transitions in the discharge in the Ar/CF2Cl2 mixture (P=10–20 kPa) was 200–300 nsec. With adding He and increasing pressure to 100 kPa the duration of the emission decreased
by a factor of 1.5–2. The basic mechanisms of the formation of Cl2, ArF, and CN(B) molecules in the transverse-discharge plasma are considered.
Uzhgorod State University, 46, Pidgirna Str., Uzhgorod, 294000, Ukraine. Translated from Zhurnal. Prikladnoi Spektroskopii,
Vol. 66, No. 2, pp. 241–246, March–April, 1999. 相似文献
15.
The current — overpotential characteristics of the H2 - Pd - SCY interphase have been studied at atmospheric total pressure and temparatures between 400 – 550 °C in the single
chamber reactor — cell: Pd | SCY | Pd. The results of I−η measurements indicate that the apparent anodic and cathodic charge
tranfer coefficients are equal to: αa=αc=0.5. The present results are compared to those obtained with the single — chamber reactor cell: Ag | SCY | Ag. A solid state
proton (H+) conducting reactor — cell with Pd electrodes was tested for the ammonia synthesis from its elements at atmospheric pressure.
At 570 °C, over 75% of the ectrochemically supplied hydrogen was converted into NH3. The thermodynamic requirement for a high pressure process was eliminated.
Paper presented at the 5th Euroconference on Solid State Ionics, Benalmádena, Spain, Sept. 13–20, 1998. 相似文献
16.
H. Li A. Farooq J.B. Jeffries R.K. Hanson 《Applied physics. B, Lasers and optics》2007,89(2-3):407-416
A fast-response (100 kHz) tunable diode laser absorption sensor is developed for measurements of temperature and H2O concentration in shock tubes, e.g. for studies of combustion chemistry. Gas temperature is determined from the ratio of
fixed-wavelength laser absorption of two H2O transitions near 7185.60 cm-1 and 7154.35 cm-1, which are selected using design rules for the target temperature range of 1000–2000 K and pressure range of 1–2 atm. Wavelength
modulation spectroscopy is employed with second-harmonic detection (WMS-2f) to improve the sensor sensitivity and accuracy.
Normalization of the second-harmonic signal by the first-harmonic signal is used to remove the need for calibration and minimize
interference from emission, scattering, beam steering, and window fouling. The laser modulation depth for each H2O transition is optimized to maximize the WMS-2f signal for the target test conditions. The WMS-2f sensor is first validated
in mixtures of H2O and Ar in a heated cell for the temperature range of 500–1200 K (P=1 atm), yielding an accuracy of 1.9% for temperature
and 1.4% for H2O concentration measurements. Shock wave tests with non-reactive H2O–Ar mixtures are then conducted to demonstrate the sensor accuracy (1.5% for temperature and 1.4% for H2O concentration) and response time at higher temperatures (1200–1700 K, P=1.3–1.6 atm).
PACS 42.62.Fi; 42.55.Px; 42.60.Fc; 07.35.+k 相似文献
17.
A systematic analysis of the electrical response of the mixed system (1-x)CuI — xAg2MoO4 (0.15≤x≤0.55) over the temperature range 297 – 447 K in the 20 Hz — 1 MHz frequency domain has been reported. Relaxation
processes associated with individual compositions of this heterogeneous mixture of polycrystalline samples have been identified
through a combined analysis of modulus and impedance spectral formalisms. The detailed analysis of these relaxation processes
has indicated that AgI and Ag2MoO4 phases are the predominant sources of electric conduction in the case of samples in the composition region 0.33≤x≤0.55 whereas
in those samples having x<0.33, the presence of Cu2MoO4 phase in the mixture is found to make a definite contribution to their effective electric conduction. 相似文献
18.
An experimental apparatus and method for investigating elastic and inelastic backscattering (180°) of low-energy (0–8 eV)
monoenergetic electrons by a solid surface are described and the first results are presented for the reflection of electrons
by samples of pure single-crystalline silicon with a polished surface (Si), doped p-type single-crystalline silicon with a porous surface (Si-p) as well as H2O and H2O2 passivated porous samples, Si-p + H2O and Si-p + H2O2. A structure due to the excitation of surface plasmons has been observed for the first time in the loss spectra. Features
corresponding to a resonance excited state of molecular nitrogen adsorbed on the surface of porous silicon have been observed
in the constant residual energy spectra.
Zh. Tekh. Fiz. 67, 103–108 (May 1997) 相似文献
19.
B. Dong X.S. Xu X.J. Wang T. Yang Y.Y. He 《Applied physics. B, Lasers and optics》2007,89(2-3):281-284
Er3+-doped Al2O3 has been prepared by a sol–gel method, using aluminium isopropoxide [Al(OC3H7)3]-derived Al2O3 sols with addition of erbium nitrate [Er(NO3)3·5H2O]. The phase structure of θ-(Al,Er)2O3 phase was obtained for the 0.1 mol. % Er3+-doped Al2O3 at the sintering temperature of 1273 K. The green and red up-conversion emissions centered at about 523, 545 and 660 nm,
corresponding respectively to the 2
H
11/2, 4
S
3/2→4
I
15/2 and 4
F
9/2→4
I
15/2 transitions of Er3+, were detected by a 978-nm semiconductor laser diode excitation. The temperature dependence of green up-conversion emissions
was studied over a wide temperature range of 295–725 K, and reasonable agreement between the calculated temperatures obtained
by the fluorescence intensity ratio theory and the measured temperature was obtained, which proved that Er3+-doped Al2O3 has a good potential for the development of high-temperature sensors. It has some advantages compared to glasses due to its
higher thermal and mechanical resistance and allows measurements in a large temperature range.
PACS 78.55.Hx; 81.40.Tv 相似文献
20.
G. E. Malashkevich V. B. Prokopenko D. V. Dem’yanenko I. M. Mel’nichenko 《Physics of the Solid State》1999,41(11):1815-1820
A sol-gel method is used to synthesize silicate films dyed in the sol stage with rhodamine C or methylene blue and further
doped with cerium or lanthanum. It is shown that this sort of doping leads to a reduction in the peak intensity and a change
in the shape of the S
1←S
0 band of the dyes, as well as to a shift in this band in a direction that depends on the H2O: Si(OC2H5)4 ratio. At the same time, the photoresistance of the rhodamine C molecules increases. The observed spectral changes are explained
by the formation of supramolecules that include organic molecules, rare earth ions, and elements from the structural grid
of the film, while the enhanced photoresistance is explained mainly by strengthening of the T
1→S
0 transitions in the dye.
Fiz. Tverd. Tela (St. Petersburg) 41, 1979–1984 (November 1999) 相似文献