傅里叶变换红外光声光谱法及其在聚合物研究中的应用

1880年,Bell发现,当一束周期性间断的阳尤照射至封闭池中固体,通过连结到池上一根听筒可以听到音响,该现象称为“光声效应”。直至本世纪七十年代初,经Rosencwaig研究,制成了第一只非谐振光声池并用于研     

用紫外光谱和X射线光电子能谱研究金属卟啉自组装膜

金属卟啉化合物由于具有丰富的电子结构和特殊的物理化学性质,因而在光电材料、分子器件和非线性光学等领域具有广阔的应用前景．有机硅可用于提高高分子化合物在氧化物基底表面的附着力;在气相和液相色谱中可作为固定相;在生物传感器中可用于蛋白质的固定．     

X射线光电子能谱研究低温氧等离子体对棉纤维表面改性

本文叙述了用X射线光电子能谱(XPS)表征棉纤维的表面特性,比较了不同方法处理的棉纤维的表面改性。还讨论了等离子体对棉纤维的润湿性和脱脂作用机理。实验表明:刻蚀、氧化、分裂和接枝含氧基团是低温氧等离子体对棉纤维表面的主要作用。     

竹木质素的红外光谱与X射线光电子能谱分析

应用傅里叶转换红外光谱(FTIR)和X射线光电子能谱(XPS), 研究了3种提纯方法得到的竹木质素及其化学反应产物的化学结构特性. 确定竹木质素C_1s的电子结合能分别为283.52 (C—H或C—C), 284.58～285.72 (C—OR或C—OH), 286.10～286.44 (C＝O或HO—C—OR), 287.65～287.72 (O—C＝O) eV. O_1s的电子结合能分别为530.31(羟基氧原子), 531.45～531.72(醛或酮的羰基氧原子), 532.73～533.74(酯键或羧酸中的羰基氧原子) eV. 竹木质素中的结构单元之间主要是通过醚键和碳碳单键连接, 慈竹磨木木质素结构单元中醚键、碳碳单键、酯键、羰基和烯双键的比例为100∶63∶32∶40∶32 (49.3∶31.0∶16.0∶19.9∶16.0)     

砷化镓半导体表面自然氧化层的X射线光电子能谱分析

用X射线光电子能谱(XPS)，测量了Ga3d和As3d光电子峰的结合能值，指认了砷化镓(GaAs)晶片表面的氧化物组成，计算了表面氧化层的厚度，定量分析了表面的化学组成；比较了几种不同的砷化镓晶片表面的差异。结果表明：砷化镓表面的自然氧化层主要由Ga2O3、As2O5、As2O3和单质As组成，表面镓砷比明显偏离理想的化学计量比，而且，氧化层的厚度随镓砷比的增大而增加；溶液处理后，砷化镓表面得到了改善。讨论了可能的机理。     

匀胶铬版表面界面微观构成的X射线光电子能谱表征

用Ｘ射线光电子能谱（ＸＰＳ）研究了几种不同工艺制备的匀胶铬版表面、铬膜内部以及各层之间界面处的微观化学组成和化学状态，讨论了不同工艺对铬版材料微观构成及宏观特性的影响。     

傅里叶变换红外光声光谱在聚合物研究中应用——Ⅰ.苧麻结构

长期以来,纤维材料需要切成细微粉末才能测得红外光谱。1981年Teramae和Tana-ka采用傅里叶变换红外光声光谱(FTIR-PAS)获得棉花及尼龙纤维的红外光声光谱图,它与常规KBr制样得到的红外光谱图一致。该法不需要复杂制样,具有快速简便、无损样品的优点,所得的光谱图便于计算。其后,有人用此法研究了各种人造纤维和天然纤维性能     

薄膜CdSe及CdSexTe1-x电极的光电子能谱研究

用X射线光电子能谱(XPS)研究了不同含氧气氛中烧结的薄膜CdSe及Cdse_xTe_1-x电极表面,以及薄膜与Ti底基之间的界面。研究中发现,二种薄膜电极的表面形成了CdO,SeO₂及TeO₂氧化物,与薄膜接触的Ti底基表面上形成了TiO₂。用俄歇电子能谱(AES)对在电极表面及Ti表面所生成的氧化层分别进行了深度分析。结果表明,各种氧化物形成的程度有很大的不同,氧化层厚度也存在差异。对影响薄膜电极的光电性能的因素进行了讨论。     

First-principles study of crystalline mono-amino-2,4,6-trinitrobenzene, 1,3-diamino-2,4,6-trinitrobenzene, and 1,3,5-triamino-2,4,6-trinitrobenzene

The electronic structure and thermodynamic properties of crystalline mono-amino-2,4,6-trinitrobenzene (MATB), 1,3-diamino-2,4,6-trinitrobenzene (DATB), and 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) have been comparatively studied using density functional theory in the local density approximation. An analysis of electronic structure shows that the CNO₂ bonds in the three solids are easier to be broken in the thermal decomposition than the CNH₂ bonds. The calculated thermodynamic properties show that the order of their thermodynamic stability is TATB > DATB > MATB and their decomposition reactions are favorable under high temperature. Finally, an attempt is made to correlate the impact sensitivity of the three solids with their band gap. The result shows that there is the relationship between the band gap and impact sensitivity.     

Raman spectroscopy of aminated and ultrafine 1,3,5-triamino-2,4,6-trinitrobenzene and PBX 9502 as a function of pressing pressure

The Raman spectra of emulsion aminated, wet aminated, dry aminated, and ultrafine 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) and PBX 9502 explosive powders are measured in a pellet die at pressures from ambient to 180 MPa with a 632.8 nm helium-neon laser. Raman peak frequencies and line widths are calculated from accurately calibrated spectra. The spectral region below 400 cm(-1), where the pressure shifts of the Raman peaks are larger, is emphasized. The most salient effect of pressing is an approximate permanent doubling of the line width of the ambient 56.9 cm(-1) peak for all TATB types. This peak is also much wider in the ultrafine TATB powder than in the other TATB powders, which indicates that the process of creating the ultrafine powder also creates changes in the TATB crystals. The peaks in the spectra of the aminated TATBs and PBX 9502 are very similar, but differences in the fluorescence backgrounds correlate with the expected crystalline purity differences from the different amination processes. The peak frequencies versus pressure for several of the more intense low-frequency peaks can be fit well to linear functions between 40 and 180 MPa. The pressure slopes of the emulsion aminated peaks are consistently larger than the slopes of the other powders. Grüneisen parameters calculated from peaks below 100 cm(-1) are scattered, which is probably caused by the anisotropy of TATB crystals and different types of intermolecular bonds.     

Investigation of the slide of the single layer of the 1,3,5-triamino-2,4,6-trinitrobenzene crystal: sliding potential and orientation

This paper reports for the first time that the sliding potential of a single layer of the 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) crystal is within 0-77.9 kJ per mol unit cell or 0-29.4 MJ/m(3) and that the most possible sliding orientation is approximately along one line. As compared to another easy-slide material, graphite, TATB has a higher sliding potential and fewer sliding routes and furthermore is more difficult to slide. However, TATB can still slide due to its highest sliding potential points below the apparent activation energy of the decomposition energy of any common explosive. This slide may be the main reason as to why TATB can be used as a desensitizer versus mechanical stimuli.     

Ultrafast shock compression and shock-induced decomposition of 1,3,5-triamino-2,4,6-trinitrobenzene subjected to a subnanosecond-duration shock: an analysis of decomposition products

Shock compression studies of pressed and confined ultrafine 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) powder were conducted using ultrashort ~300 ps, ~50 GPa shock waves. The recovered decomposition products were characterized using X-ray photoelectron spectroscopy, infrared spectroscopy, and Raman spectroscopy. A substantial amount of shock-related chemistry was observed. Approximately 75% of the nitrogen atoms were liberated as gas-phase species, along with ~33% of the oxygen atoms, as a result of the applied shock. Furthermore, we observe C 1s binding energies suggesting the formation of sp(3) hybridized amorphous carbon. For comparison, a carbon nitride material was also prepared and characterized by thermally pyrolizing TATB. The shock-compressed TATB and the thermally pyrolized TATB are qualitatively different, suggesting that, carbon nitrides, a possible indicator of nitrogen-rich heterocycles precursors, are not a major product class for strongly overdriven shock conditions. These experimental conditions were, however, not detonation conditions, and the possible formation of nitrogen-rich heterocycles in actual detonations still exists.     

Photolysis of the Insensitive Explosive 1,3,5-Triamino-2,4,6-trinitrobenzene (TATB)

The explosive 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) is of particular interest due to its extreme insensitivity to impact, shock and heat, while providing a good detonation velocity. To determine its fate under environmental conditions, TATB powder was irradiated with simulated sunlight and, in water, under UV light at 254 nm. The hydrolysis of particles submerged in neutral and alkaline solutions was also examined. We found that, by changing experimental conditions (e.g., light source, and mass and physical state of TATB), the intermediates and final products were slightly different. Mono-benzofurazan was the major transformation product in both irradiation systems. Two minor transformation products, the aci-nitro form of TATB and 3,5-diamino-2,4,6-trinitrophenol, were detected under solar light, while 1,3,5-triamino-2-nitroso-4,6-dinitrobenzene, 1,3,5-triamino-2,4-dinitrobenzene and mono-benzofuroxan were produced under UV light. The product identified as 3,5-diamino-2,4,6-trinitrophenol was identical to the one formed in the dark under alkaline conditions (pH 13) and in water incubated at either 50 °C or aged at ambient conditions. Interestingly, when only a few milligrams of TATB were irradiated with simulated sunlight, the aci-isomer and mono-benzofurazan derivative were detected; however, the hydrolysis product 3,5-diamino-2,4,6-trinitrophenol formed only much later in the absence of light. This suggests that the water released from TATB to form mono-benzofurazan was trapped in the interstitial space between the TATB layers and slowly hydrolyzed the relatively stable aci-nitro intermediate to 3,5-diamino-2,4,6-trinitrophenol. This environmentally relevant discovery provides data on the fate of TATB in surface environments exposed to sunlight, which can transform the insoluble substrate into more soluble and corrosive derivatives, such as 3,5-diamino-2,4,6-trinitrophenol, and that some hydrolytic transformation can continue even without light.     

Spectroscopic and thermal studies on the decomposition of l,3,5-triamino-2,4,6-trinitrobenzene (TATB)

The kinetics of the thermal decomposition of 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) in condensed state has been investigated by high temperature infrared spectroscopy (IR) and thermogravimetry (TG) in conjunction with pyrolysis gas analysis, differential thermal analysis (DTA) and hot stage microscopy. The decomposition proceeds in two main stages under isothermal conditions and the initial stage involving about 24% loss in weight obeys Avrami-Erofe'ev equation (n= 1), and is governed by an activation energy (E) of 150.58 kJ·mol^–1 and log(A in s^–1) 12.06. The second stage corresponding to 24 to 90% loss in weight gave best fit for Avrami-Erofe'ev equation,n=2, withE=239.56 kJ·mol^–1 and log(A in s^–1) 19.88 by isothermal TG. The effect of additives, on the initial thermolysis of TATB has also been studied. Evolved gas analysis by IR showed that NH₃, CO₂, NO₂, HCN and H₂O are produced in the initial stage of decomposition. The decomposition in KBr matrix in the temperature range 272 to 311.5°C shows relative preferential loss in the -NH₂ to -NO₂ band intensity which indicates that the rupture of C-NH₂ bond, weakened also by the interaction of the NH₂ with the neighbouring NO₂ group, appears to be the primary step in the thermolysis of TATB.     

VDF-CTFE共聚物在TATB表面吸附链构象的分子动力学模拟

采用COMPASS力场和NVT正则系综的动力学计算模拟了偏氟乙烯(PVDF)与三氟氯乙烯(PCTFE)及其共聚物在1,3,5-三氨基-2,4,6-三硝基苯(TATB)表面吸附能和吸附链的构象. 结果表明, 氟聚合物链与TATB表面距离小于0.8 nm时, 产生吸附放热效应. 在TATB表面, PVDF有强吸附作用, 而PCTFE的吸附能力差. 对VDF与CTFE单体摩尔比为1∶1, 1∶2, 1∶3和1∶4的共聚物吸附模拟结果表明, 共聚物的组成和链的序列结构对其在TATB表面的吸附行为和吸附链构象影响很大. 单体摩尔比为1∶2的交替共聚物链的吸附效果最佳. 随着共聚物链段中PCTFE链节的增加, 聚合物链的刚性增大, 在TATB表面吸附能力逐渐下降、吸附能亦降低, 尾型(tail)或环型(loop)构象数逐渐增多.     

Thermal degradation kinetics and reaction models of 1,3,5-triamino-2,4,6-trinitrobenzene-based plastic-bonded explosives containing fluoropolymer matrices

In this article, thermal degradation behavior of 1,3,5-triamino-2,4,6-trinitrobenzene (TATB)-based plastic-bonded explosives (PBXs) bonded with a different fluoropolymer matrices namely indigenous poly(vinylidene fluoride-chlorotrifluoroethylene) (FKM), FK 800, fluoroplastic F-32L and fluororubber SKF 32 was investigated through non-isothermal thermogravimetric analysis (TG) technique under nitrogen atmosphere. It was observed that the mass loss of PBXs containing FKM and FK 800 matrices occurred in three steps. The mass loss of PBXs containing fluoroplastic F-32L and fluororubber SKF 32 occurred in two steps. Kinetics were investigated through non-isothermal TG at different heating rates for the first step of degradation by means of model-free Flynn–Wall–Ozawa (FWO) and Kissinger–Akahira–Sunose (KAS) methods. The activation energies calculated by applying FWO method are in good agreement and very close to those obtained by KAS method. The results revealed that the effect of the polymer matrices on the thermal degradation reaction of TATB was significantly observed especially different outcomes of kinetic parameters. The reaction models for degradation were also studied by Criado method. The reaction models are probably best described by the power law and diffusion models.