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11.
《Surface and interface analysis : SIA》2003,35(12):998-1003
The electronic structure of heated SrTiO3(110) surfaces was investigated with metastable impact electron spectroscopy and ultraviolet photoelectron spectroscopy (He(I)). Scanning tunnelling microscopy and atomic force microscopy (AFM) were used to study the topology of the surface. The crystals were heated up to 1000°C under reducing conditions in ultrahigh vacuum or under oxidizing conditions in synthetic air for 1 h, respectively. Under both conditions microfacetting of the surface is observed. The experimental results are compared with ab initio Hartree–Fock calculations, also presented here, carried out for both ideal and reconstructed SrTiO3(110) surfaces. The results give direct evidence for Ti termination of the faceted TiO2 rows. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
12.
Dr. Eddy W. T. Yemeli Dr. Graeme R. Blake Dr. Alexios P. Douvalis Prof. Thomas Bakas Gert O. R. Alberda van Ekenstein Dr. Petra J. van Koningsbruggen 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(72):16766-16776
The iron(III) spin-crossover compounds [Fe(Hthsa)(thsa)] ⋅ H2O ( 1 ), [Fe(Hth5Clsa)(th5Clsa)2] ⋅ H2O ( 2 ), and [Fe(Hth5Brsa)(th5Brsa)2] ⋅ H2O ( 3 ) (H2thsa=salicylaldehyde thiosemicarbazone, H2th5Clsa=5-chlorosalicylaldehyde thiosemicarbazone, and H2th5Brsa=5-bromosalicylaldehyde thiosemicarbazone) have been synthesized and their spin-transition properties investigated by magnetic susceptibility, Mössbauer spectroscopy, and differential scanning calorimetry measurements. The three compounds exhibit an abrupt spin transition with a thermal hysteresis effect. The more polarizable the substituent on the salicylaldehyde moiety, the more complete is the transition at room temperature with an increased degree of cooperativity. The molecular structures of 1 and 2 in the high-spin state are revealed. The occurrence of the light-induced excited-spin-state trapping phenomenon appears to be dependent on the substituent incorporated into the 5-position of the salicylaldehyde subunit. Whereas the compounds with an electron-withdrawing group (-Br or -Cl) exhibit light-induced trapped excited high-spin states with great longevity of metastability, the halogen-free compound does not, even though strong intermolecular interactions (such as hydrogen-bonding networks and π stacking) operate in the system. For compound 2 , the surface level of photoconversion is less than 35 %. In contrast, compound 3 displays full photoexcitation. 相似文献
13.
Felix Franks 《Journal of solution chemistry》1995,24(11):1093-1097
At a recent meeting of the International Symposium on Solution Chemistry I presented a paper dealing with aqueous solutions in which water was present not in excess but as one component of a supersaturated solution with polyhydroxy compounds. In response to a request from the Editor of this Journal I have submitted this article in which I outline my general interest in the subject and its importance as a new direction for solution chemists. 相似文献
14.
Diamy A.-M. Hochard L. Legrand J.-C. Ricard A. 《Plasma Chemistry and Plasma Processing》1998,18(4):447-460
Measurements of nitrogen atom density, by means of NO chemical titration, along with an evaluation of the densities of some excited species N
2
(B, v=11), N
2
(B, v=2), N
2
(C, v=0), and N
2
+
(B,v=0), by means of a spectroscopic study of some bands of dinitrogen, are achieved along the flowing afterglow of a dinitrogen microwave plasma (2450 MHz) for several pressures. The concentrations obtained are in the following range: [N]10
+15
, [N
2
(B, 2)]10
+9
–10
+10
, [N
2
(B, 11)]10
+8
–10
+9
, [N
2
(C, 0)]10
+6
–10
+7
, [N
2
+
(B,0)]10
+6
-10
+8
(cm-3). From a kinetic study of the formation and decay of excited and charged species, an estimation of N
2
(A, v), N
2
(X, v, and N
2
+
(X) densities can be derived: [N
2
(A, v)]10
+12
, [N
2
(X, v6)]10
+15
–10
+16
, [N
2
(X, v12)]10
+14
–10
+15
, [N
2
+
(X)]10
+10
(cm
-3
). 相似文献
15.
F. J. Romero M. C. Gallardo A. Czarnecka M. Koralewski J. del Cerro 《Journal of Thermal Analysis and Calorimetry》2007,87(2):357-363
The specific heat
and the enthalpy variation of a highly deuterated crystal of ferroelectric
triglycine selenate have been measured around its first-order phase transition
using the technique square modulated differential thermal analysis (SMDTA).
The low temperature variation rate has allowed analyzing the kinetics of the
phase transition. Due to an internal crack in the sample, the transition is
carried out in two steps and an intermediate region where the transition is
blocked and both phases coexist without transformation has been found. The
latent heat on cooling (L
c=1.32±0.02
J g–1) is higher than on heating (L
h=1.08±0.02 J g–1)
due to the thermal hysteresis and the great difference between the specific
heat in both phases. Nevertheless, the enthalpy balance is fulfilled on heating
and on cooling. 相似文献
16.
Muliadi Ramli Nasrullah Idris Kenichi Fukumoto Hideaki Niki Fujio Sakan Tadashi Maruyama Koo Hendrik Kurniawan Tjung Jie Lie Kiichiro Kagawa 《Spectrochimica Acta Part B: Atomic Spectroscopy》2007,62(12):1379-1389
A TEA CO2 laser (350 mJ–1.5 J, 10.6 μm, 200 ns, 10 Hz) was focused onto a metal sub-target under He as host gas at 1 atmospheric pressure with a small amount of impurity gas, such as water and ethanol vapors. It was found that the TEA CO2 laser with the help of the metal sub-target is favorable for generating a strong, large volume helium gas breakdown plasma at 1 atmospheric pressure, in which the helium metastable-excited state was then produced overwhelmingly. While the metal sub-target itself was never ablated. The helium metastable-excited state produced after the strong helium gas breakdown plasma was considered to play an important role in exciting the atoms. This was confirmed by the specific characteristics of the detected H emission, namely the strong intensity with low background, narrow spectral width, and the long lifetime. This technique can be used for gas and solid samples analysis. For nonmetal solid analysis, a metal mesh was introduced in front of the nonmetal sample surface to help initiation of the helium gas breakdown plasma. For metal sample, analysis can be carried out by combining the TEA CO2 laser and an Nd–YAG laser where the Nd–YAG laser is used to ablate the metal sample. The ablated atoms from the metal sample are then sent into the region of helium gas breakdown plasma induced by the TEA CO2 laser to be excited through the helium metastable-excited state. This technique can be extended to the analysis of other elements, not limited only to hydrogen, such as halogens. 相似文献
17.
亚稳态分子间复合物(metastable intermolecular composite,MIC)由于具有超高反应燃烧速率及能量释放速率、高体积能量密度、低扩散距离和绿色环保等优点,在微型含能器件、火箭推进剂和绿色火工药剂等军用领域展现了很好的应用潜力。其反应机制与传统的含能材料不同,且具有超高速反应的瞬时性及复杂性,对其反应机理仍然缺乏清晰的认识,这限制了其应用研究的进展。本文对近年来亚稳态分子间复合物的反应机理研究进行综述,重点讨论具有代表性的“金属-氧翻转机理”和“预点火-熔结机理”。对于MIC材料的反应机理研究,本文主要从实验研究、理论模型研究和数值模拟研究三个方面进行分析。改性MIC材料是对材料性能进行调控的重要手段,是目前及未来的重要发展趋势之一,在论文最后对其反应机理做了重点叙述。通过对当前研究现状的归纳与分析,给出了当前的重要研究成果以及研究中出现的问题,并对未来的研究发展趋势进行了展望。 相似文献
18.
The thermodynamic properties of saturated aqueous lanthanide nitrate solutions were determined using recently published critically evaluated solubility and activity data. The variation of the thermodynamic functions and congruent melting points as a function of atomic number are interpreted in terms of changes in inner sphere coordination number in both the solid hexahydrates and in the aquo ions, and in terms of the double-double effect.Inconsistencies in experimental solubility data are generally caused by uncertainties in solid phase composition which is shown to be due to the very small Gibbs energies accompanying transitions from stable to metastable systems differing in the number of hydrating water molecules.Presentation to First International Symposium on Solubility Phenomena, University of Western Ontario, London, Ontario, August 21–23, 1984. 相似文献
19.
20.
Low-and high-resolution mass spectra and spectra of metastable ions were studied using direct analysis of daughter ions (DADI)
and metastable defocusing (MD) of lagochiline-type diterpenoids. Patterns in their fragmentation were found.
__________
Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 56–60, January–February, 2007. 相似文献