Department of Physics, Oklahoma State University, Stillwater, Oklahoma 74078-3072, USA.
J Chem Phys. 2011 Aug 28;135(8):084313. doi: 10.1063/1.3631342.
A novel optical method has been developed for the measurement of thermal accommodation coefficients in the temperature-jump regime. The temperature dependence of the resonant frequency of a fused-silica microresonator's whispering-gallery mode is used to measure the rate at which the microresonator comes into thermal equilibrium with the ambient gas. The thermal relaxation time is related to the thermal conductivity of the gas under some simplifying assumptions and measuring this time as a function of gas pressure determines the thermal accommodation coefficient. Using a low-power tunable diode laser of wavelength around 1570 nm to probe a microsphere's whispering-gallery mode through tapered-fiber coupling, we have measured the accommodation coefficients of air, helium, and nitrogen on fused silica at room temperature. In addition, by applying thin-film coatings to the microsphere's surface, we have demonstrated that accommodation coefficients can be measured for various gases on a wide range of modified surfaces using this method.
一种新的光学方法已被开发用于在温度跃变区测量热弛豫系数。利用熔融硅微谐振器的 whispering-gallery 模式的共振频率随温度的变化来测量微谐振器与环境气体达到热平衡的速率。在一些简化假设下，热弛豫时间与气体的热导率有关，通过测量这个时间作为气体压力的函数来确定热弛豫系数。我们使用波长约为 1570nm 的低功率可调谐二极管激光器通过锥形光纤耦合来探测微球的 whispering-gallery 模式，已经测量了室温下空气、氦气和氮气在熔融硅上的热弛豫系数。此外，通过在微球表面涂覆薄膜，我们已经证明，通过这种方法可以在广泛的改性表面上测量各种气体的热弛豫系数。
