Department of Physics and Astronomy, Mississippi State University, Mississippi State, MS 39762, USA.
Sensors (Basel). 2013 Jun 26;13(7):8170-87. doi: 10.3390/s130708170.
The weak absorption spectra of isoprene and acetone have been measured in the wavelength range of 261-275 nm using cavity ringdown spectroscopy. The measured absorption cross-sections of isoprene in the wavelength region of 261-266 nm range from 3.65 × 10⁻²¹ cm².molecule⁻¹ at 261 nm to 1.42 × 10⁻²¹ cm².molecule⁻¹ at 266 nm; these numbers are in good agreement with the values reported in the literature. In the longer wavelength range of 270-275 nm, however, where attractive applications using a single wavelength compact diode laser operating at 274 nm is located, isoprene has been reported in the literature to have no absorption (too weak to be detected). Small absorption cross-sections of isoprene in this longer wavelength region are measured using cavity ringdown spectroscopy for the first time in this work, i.e., 6.20 × 10⁻²³ cm².molecule⁻¹ at 275 nm. With the same experimental system, wavelength-dependent absorption cross-sections of acetone have also been measured. Theoretical detection limits of isoprene and comparisons of absorbance of isoprene, acetone, and healthy breath gas in this wavelength region are also discussed.
采用腔衰荡光谱法在 261-275nm 的波长范围内测量了异戊二烯和丙酮的弱吸收光谱。在 261-266nm 的波长区域，异戊二烯的测量吸收截面范围从 261nm 的 3.65×10⁻²¹cm²·molecule⁻¹到 266nm 的 1.42×10⁻²¹cm²·molecule⁻¹；这些数值与文献中报道的值吻合良好。然而，在更长的 270-275nm 波长范围内，文献中报道异戊二烯没有吸收（太弱以至于无法检测到），而该波长范围中吸引人的应用是使用 274nm 的单波长紧凑型二极管激光。本文首次采用腔衰荡光谱法在这个更长的波长范围内测量了异戊二烯的小吸收截面，即在 275nm 时为 6.20×10⁻²³cm²·molecule⁻¹。使用相同的实验系统，还测量了丙酮的波长相关吸收截面。本文还讨论了异戊二烯的理论检测极限以及该波长范围内异戊二烯、丙酮和健康呼吸气体的吸光度比较。
