...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Science and Technology of Advanced Materials >Luminiscent dye Rhodamine 6G doped monolithic and transparent TEOS silica xerogels and spectral properties
【24h】

Luminiscent dye Rhodamine 6G doped monolithic and transparent TEOS silica xerogels and spectral properties

机译：发光染料若丹明6G掺杂的整体和透明TEOS二氧化硅干凝胶和光谱性质

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

Sol-gel process was used for the preparation of Rhodamine 6G (R6G) doped silica xerogels, using tetraethylorthosilicate [TEOS, Si(OC_2H_5)_4] as the precursor for the silica network. Silica alcosol was prepared by hydrolysis and polycondensation of ethanol (EtOH) diluted TEOS in the presence of citric acid (CTA) catalyst. The ethanolic R6G was added to the alcosol to trap R6G molecules inside the SiO_2 gel network during the gelation of the TEOS alcosol. The effect of CTA/TEOS molar ratio on the gelation time of the R6G doped TEOS alcosol, transparency and monolithicity of the R6G doped silica xerogel was studied by varying the CTA/TEOS molar ratio from 1.2 X 10~(-4) to 180 X 10~(-4) by keeping the molar ratios of TEOS:EtOH:H_2O:R6G constant at 1:5:7:9.2 X 10~(-6), respectively. It was found that the minimum (<70 h) gelation time was observed at higher and lower CTA/TEOS molar ratios of 72 X 10~(-4) where as maximum (> 180 h) gelation time was observed for CTA/TEOS molar ratio of 72 X 10~(-4). While opaque and monolithic R6G doped SiO_2 xerogels were obtained for <4.8 X 10~(-4) CTA/TEOS molar ratios, whereas cracked and transparent xerogels were obtained for >120 X 10~(-4) molar ratios of CTA/TEOS. Transparent, homogeneous and monolithic samples were obtained between 4.8 X 10~(-4) and 120 X 10~(-4) of CTA/TEOS molar ratios. Leaching out property was studied by using water, methanol and ethanol solvents for the R6G doped SiO_2 xerogels of 9.2 X 10~(-6) and 12 X 10~(-4) of R6G/TEOS and CTA/TEOS molar ratios, respectively, and found that R6G molecules were trapped in the pores of the SiO_2 network. Bleaching out phenomena of the R6G doped SiO_2 xerogels was studied by focusing the high intensity light on some part of the samples for a period of 1 h and found that the pores were continuous in SiO_2 network. Visible spectra of R6G in water, ethanol, SiO_2 alcosol and xerogel were taken for 1.6 X 10~(-4) M R6G and observed that there were two absorption peaks at 499 and 525 nm in the spectrum of R6G in water due to dimerization of R6G molecules and only one absorption peak at 530 nm in the spectra of ethanol, SiO_2 alcosol and xerogel because of monomerization of R6G molecules. Visible spectra of the R6G doped silica xerogels for varying R6G/TEOS molar ratios from 9.2 X 10~(-8) to 9.2 X 10~(-5) were taken and found the red shift (5-10 nm) with increasing the R6G/TEOS molar ratio from 9.2 X 10~(-8) to 9.2 X 10~(-5). The effect of temperature on these sample was studied by varying the temperature from 50 to 300 ℃ and found that the R6G doped silica samples were stable up to 200 ℃. IR spectra were taken for pure R6G powder and R6G doped silica xerogels of 9.2 X 10~(-8) and 9.2 X 10~(-5) R6G/TEOS molar ratios and found that most of the peaks present in pure R6G powder spectrum were absent in the spectra of trapped R6G SiO_2 xerogels. This shows that, the SiO_2 network hinders the rotational and vibrational transitions of R6G when it is caged in the SiO_2 network. The peaks related to bending motion in R6G molecules were not disturbed by the SiO_2 network ? 2003 Elsevier Science Ltd. All rights reserved.
机译：使用原硅酸四乙酯[TEOS，Si（OC_2H_5）_4]作为二氧化硅网络的前体，采用溶胶-凝胶法制备了罗丹明6G（R6G）掺杂的二氧化硅干凝胶。二氧化硅醇是通过在柠檬酸（CTA）催化剂存在下将乙醇（EtOH）稀释的TEOS水解和缩聚而制备的。在TEOS醇溶胶凝胶化过程中，将乙醇R6G添加到醇溶胶中，将R6G分子捕获在SiO_2凝胶网络内部。通过将CTA / TEOS摩尔比从1.2 X 10〜（-4）更改为180 X，研究了CTA / TEOS摩尔比对R6G掺杂的TEOS醇凝胶化时间，R6G掺杂的二氧化硅干凝胶的透明性和整体性的影响。通过保持TEOS：EtOH：H_2O：R6G的摩尔比分别恒定在1：5：7：9.2 X 10〜（-6）来获得10〜（-4）。发现在较高和较低的CTA / TEOS摩尔比为72 X 10〜（-4）时观察到最小（<70 h）的胶凝时间，其中CTA / TEOS摩尔观察到最大（> 180 h）的胶凝时间。比率为72 X 10〜（-4）当CTA / TEOS摩尔比小于4.8 X 10〜（-4）时，可以得到不透明，整体的R6G掺杂的SiO_2干凝胶，而当CTA / TEOS摩尔比大于120 X 10〜（-4）时，可以得到开裂和透明的干凝胶。获得的透明，均质和整体样品的CTA / TEOS摩尔比为4.8 X 10〜（-4）至120 X 10〜（-4）。研究了水，甲醇和乙醇溶剂对R6G / TEOS和CTA / TEOS摩尔比分别为9.2 X 10〜（-6）和12 X 10〜（-4）的R6G掺杂的SiO_2干凝胶的浸出性能，并且发现R6G分子被困在SiO_2网络的孔中。通过将高强度光聚焦在样品的某些部分上1 h的时间，研究了R6G掺杂SiO_2干凝胶的漂白现象，发现SiO_2网络中的孔是连续的。以1.6 X 10〜（-4）M R6G拍摄水，乙醇，SiO_2醇溶胶和干凝胶中R6G的可见光谱，并观察到由于R6G的二聚作用，R6G在水中的光谱在499和525 nm处有两个吸收峰。由于R6G分子的单体化，在乙醇，SiO_2醇溶胶和干凝胶的光谱中，R6G分子只有一个吸收峰在530 nm处。随R6G / TEOS摩尔比从9.2 X 10〜（-8）到9.2 X 10〜（-5）的变化，对R6G掺杂的二氧化硅干凝胶的可见光谱进行了测量，发现随着R6G的增加，红移（5-10 nm） / TEOS摩尔比从9.2 X 10〜（-8）到9.2 X 10〜（-5）。通过将温度从50℃改变到300℃，研究了温度对这些样品的影响，发现R6G掺杂的二氧化硅样品在200℃以下都稳定。对纯R6G粉末和9.2 X 10〜（-8）和9.2 X 10〜（-5）R6G / TEOS摩尔比的R6G掺杂的硅胶干凝胶进行红外光谱分析，发现纯R6G粉末光谱中存在的大多数峰为捕获的R6G SiO_2干凝胶的光谱中没有。这表明，当SiO_2网络笼罩在SiO_2网络中时，它会阻碍R6G的旋转和振动跃迁。 R6G分子中与弯曲运动有关的峰不受SiO_2网络干扰吗？ 2003 Elsevier Science Ltd.保留所有权利。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号