Low-limit detection of NO2 by longitudinal mode selection in a photoacoustic resonant system

Pramana

A K Chaudhary1¹  F Yehya¹ 

[1] Advanced Centre of Research in High Energy Materials, University of Hyderabad, Hyderabad 500 046, India$$

关键词: Photoacoustic;    pulsed laser;    second longitudinal mode;    filters;    NO2 .;   

DOI  :  

学科分类：物理（综合）

来源: Indian Academy of Sciences

【 摘 要 】

The paper reports the pulsed laser-based photoacoustic (PA) spectroscopy of NO2 in a resonant PA cavity with special filters made of stainless steel. The PA cell along with special types of sound filters are designed and fabricated to excite only the second-order longitudinal mode inside the cavity. The second harmonic, i.e. 𝜆 = 532 nm pulse width, of 7 ns obtained from 𝑄-switched Nd:YAG laser at 10 Hz repetition rate has been used to study the saturation behaviour of the PA signal and absorption coefficient with respect to the input laser energy. Generally, the 𝑄-factor of longitudinal modes in the acoustic cavities is quite low. However, by modifying the design of the cell and the filter, we can achieve high value of 𝑄 = 30. The combination of special filter along with the experimental data acquisition technique helped us to achieve the minimum detection concentration of NO2 of the order of 9 ppbV which is much better than the previous value of the same PA cell without filter [Yehya and Chaudhary, Appl. Phys. B 106, 953 (2012)].

【 授权许可】

Unknown