Deposition Of Gold Onto The Inner Surface Of Quartz Capillary And Its Application In The Enhanced Laser Raman Detection Of Gas

Laser Raman spectroscopy is a kind of vibration spectrum, it has a wide range of applications in the research of materials microstructure, sample scanning, low temperature analysis and other fields. Compared with other detection methods (such as infrared spectrum detection and gas chromatography), Raman detection has the advantage of fast speed, detection of low cost and strong anti-jamming capability. At present, the technique of the Raman detection in the liquid or solid is relatively mature, but the technique of the Raman detection in gas samples still faces great difficulties, the main reason is that gas molecule scattering cross section is small, the Raman signal intensity is very weak, so it is difficult to achieve sensitive and accurate detection. In order to solve this problem, this study proposed by gold quartz capillary to improve the Raman detection effect of the gas. Because that the gold film can multiplely reflect laser signal, the local surface plasmons are caused by the electromagnetic enhancement, it makes the Raman scattering signal of the gas enhanced.In the first part, we explored the method of wet plating of gold onto the quartz capillary. Firstly, we studied gold plating the quartz glass, and optimized the process conditions. Then this method was applied to the quartz capillary. Gold-plated quartz surface specific process is as follows:(1) hydroxylation of quartz surface by chemical etching method, then modification organic silane (3-ammonia propyl silane three oxygen radicals) on the hydroxylation quartz surface; (2) By chemical reduction method synthesis of nanometer gold sol, contacting with the silanization quartz surface, due to the exposed surface amino silane protoned with positively charged, negatively charged gold nanoparticles adsorped on quartz surface by static adsorption; (3) Finally, the assembled gold sol monolayer as seed layer, induced gold chloride acid chemical reduction deposition to generate dense homogeneous gold film. To be used for gas Raman, compared with no gold-plated quartz capillary, we found gold-plated capillary in the Raman signal enhancement effect is good, but the problem is that the binding force of gold plating with capillary is poor, and the layer is too thin. The next step we will continue to explore new methods of quartz capillary gilded.In the second part, we explored the method of palladium sol catalytic plating of gold onto the quartz capillary. Use the method of the first part of the capillary surface modification, firstly the capillary wall hydroxylation, silicon alkylation, reacting with the negatively charged palladium sol through electrostatic interactions, modified palladium nanoparticles. Using palladium high catalytic activity and the nickel autocatalytic activity, grow nickel film layer on the inner wall. Finally, nickel as the catalytic center, catalyze the reduction of gold, generating dense gold film. To be used for gas Raman tests, compared with no gold-deposited quartz capillary, we found gold-deposited capillary in the Raman signal enhancement effect is good, reaching more than six times. According to this method, we designed an automated equipment deposition of gold onto the inner surface of quartz capillary, simplifying operation and reducing human error, improving the success rate of the gold-deposited capillary, making a substantial contribution for the laser Raman gas analyzer development.