Dipartimento di Matematica e Fisica, Università degli Studi della Campania "Luigi Vanvitelli," Viale Lincoln 5, 81100 Caserta, Italy.
Department of Physics and Astronomy, University College London, London WC1E 6BT, United Kingdom.
J Chem Phys. 2017 Jun 28;146(24):244309. doi: 10.1063/1.4989925.
Line intensities for carbon dioxide are measured with a novel spectroscopic approach, assisted by an optical frequency comb synthesizer for frequency calibration purposes. The main feature of the spectrometer consists in the exploitation of optical feedback from a V-shaped high-finesse optical resonator to effectively narrow a distributed feedback diode laser at the wavelength of 2 μm. Laser-gas interaction takes place inside an isothermal cell, which is placed on the transmission from the cavity. High quality, self-calibrated, absorption spectra are observed in pure CO samples at different gas pressures, in coincidence with three lines of the R-branch of the ν + 2ν + ν band. Line intensities are determined using a global fitting approach in which a manifold of spectra are simultaneously analyzed across the range of pressures between 5 and 100 Torr, sharing a restricted number of unknown parameters. Various sources of uncertainty have been identified and carefully quantified, thus leading to an overall uncertainty ranging between 0.17% and 0.23%. The measured values are in a very good agreement with recent ab initio predictions.
采用一种新颖的光谱方法测量二氧化碳的谱线强度，该方法借助光学频率梳合成器进行频率校准。光谱仪的主要特点是利用 V 形高精细度光学谐振器的光反馈，有效地将分布式反馈二极管激光器在 2 μm 波长处进行窄化。激光与气体的相互作用发生在等温池中，等温池位于腔的传输路径上。在不同的气体压力下，在纯 CO 样品中观察到高质量、自校准的吸收光谱，与 ν + 2ν + ν 带的 R 支的三条谱线吻合。通过全局拟合方法确定谱线强度，该方法同时分析在 5 到 100 托之间压力范围内的多个光谱，这些光谱共享有限数量的未知参数。已经确定并仔细量化了各种不确定来源，从而导致整体不确定度在 0.17%到 0.23%之间。测量值与最近的从头算预测非常吻合。
