• <tr id="yyy80"></tr>
  • <sup id="yyy80"></sup>
  • <tfoot id="yyy80"><noscript id="yyy80"></noscript></tfoot>
  • 99热精品在线国产_美女午夜性视频免费_国产精品国产高清国产av_av欧美777_自拍偷自拍亚洲精品老妇_亚洲熟女精品中文字幕_www日本黄色视频网_国产精品野战在线观看 ?

    In Situ TEM Observation of Radiolysis and Condensation of Water via Graphene Liquid Cell

    2019-01-23 08:21:58HUQiJINChuanhong
    物理化學(xué)學(xué)報 2019年1期

    HU Qi, JIN Chuanhong

    State Key Laboratory of Silicon Materials, School of Materials Science and Engineering, Zhejiang University, Hangzhou 310027,P. R. China.

    Abstract: Water is involved in many important physical, chemical,and biological phenomena. However, not much is known about water at the nanoscale level, such as about its radiolysis and condensation,because of the experimental difficulties of imaging liquid at such a length-scale. The newly developed graphene liquid cell (GLC)technique facilitates imaging dynamic events in a liquid medium with unprecedented resolution while sustaining the most realistic liquid condition achievable under electron-beam irradiation. The graphene liquid cell was fabricated by the wet transfer of monolayer graphene synthesized by chemical vapor deposition to a graphene-supported transmission electron microscope (TEM) grid, and the water islands were naturally captured during the wet transfer process. Compared with traditional, commercial silicon nitride cells, the fabrication of graphene liquid cells required higher expertise and thus related research reports are limited. Here,we used graphene liquid cells for in situ TEM observation of dynamic behaviors of entrapped water between two layers of graphene. The radiolysis and condensation processes of water could be modulated by controlling the electron dose rate.We showed that a high electron dose rate yields supersaturated concentration of gas molecules in a liquid system, and the excess gas then dissolve out in the form of a series of nanobubbles at a low dose rate. From The quantitative and statistical analyses of the dynamic processes of the confined liquid showed that the growth of the nanobubbles is limited by interface reactions and the newly formed nanobubble inhibits the growth of the existing one. The gas molecules inside the nanobubbles are in a “dense gas” phase and the density number ratio of the gas molecules inside each nanobubble decreases during the growth process of each nanobubble. The total number of gas molecules increases approximately linearly with time. A fixed middle dose rate leads to the condensation of droplets, with repeat growth/dissolution processes on the inner wall of graphene. The contact angles at the water-graphene interface are less than 90°, suggesting that the scrolled graphene is hydrophilic. Using in situ GLC-TEM imaging, we directly observed the dynamic processes involved in beam-induced bubble formation in liquid and nanodroplet condensation from vapor at the preferential sites. Some unexpected and so-far undiscovered phenomena involving both nanobubbles and nanodroplets were observed and investigated in detail, which increased our knowledge on the behaviors of the nanoconfined liquid. Our results presented here would serve as an important reference to understand the vapor/liquid interface transition in a nanoconfined space and electron-water interactions in liquid cell TEM. The experiment and method reported here may help find further applications of the new graphene liquid cell technique. The use of graphene liquid cell will also help a wide range of studies on reactions and process dynamics in material science and biochemistry that either have not been explored or need more detailed understanding.

    Key Words: Graphene liquid cell; In situ TEM; Electron dose rate; Radiolysis; Condensation

    昆山市| 茂名市| 雷波县| 祁阳县| 浑源县| 佛山市| 雷波县| 松滋市| 临高县| 宽城| 米易县| 双辽市| 富民县| 奉贤区| 沅江市| 五台县| 绥滨县| 周口市| 荆州市| 旅游| 清徐县| 四平市| 新化县| 湛江市| 新和县| 正定县| 阿勒泰市| 清水县| 云南省| 金沙县| 桂平市| 胶南市| 嫩江县| 左云县| 扎鲁特旗| 阳泉市| 昂仁县| 卓尼县| 海阳市| 霍州市| 砚山县|