6590 cm^(-1)附近N_2O分子的连续波腔衰荡光谱测量

Measurement of N_2O Spectrum near 6590 cm^(-1) with Continuous-Wave Cavity Ring-Down Spectroscopy

以超低膨胀系数微晶玻璃为腔体,以分布反馈(DFB)激光器为光源,建立了一套高灵敏度连续波腔哀荡光谱测量系统。该系统通过扫描腔长来实现入射激光与衰荡腔的频率匹配,通过DFB激光器的电流调制实现入射光的快速关断,通过DFB激光器的温度、电流调谐实现系统的光谱扫描,7.6×10^(-9)cm^(-1)的测量灵敏度。结合超高真空系统,对N_2O在6586.5～6596.5 cm^(-1)的19条N_2O吸收谱线的吸收强度及多普勒展宽系数进行了测量,并就测量结果与HITRAN2004数据库进行了比较和讨论。

A high-sensitivity system of continuous wave cavity ringdown spectroscopy （CW-CRDS） is presented, which uses an ultralow-thermal expansion glass-ceramic as the cavity and a Distributed-Feedback （DFB） laser diode as the light source. In the system, the laser frequency overlaps with one of cavity modes via scanning the cavity length. And the input laser is switched off or on by modulating the injection current of laser diode. Furthermore, the laser wavelength is scanned by tuning its operating temperature or injection current. The noise-equivalent detection sensitivity of 7.6 × 10^-9 cm^-1 is achieved in 24.9 cm cavity length. With an ultra-high vacuum system, the intensity and doppler broadening line-width of 19 spectral lines of N2O molecule in the range of 6586.5- 6596.5 cm^-1 are measured, and then the difference between measurement results and that of Hitran2004 database is discussed.