We present broadband dual frequency comb laser absorption measurements of 2 % HO (natural isotopic abundance of 99.7 % HO) in air from 6600 to 7650 cm (1307–1515 nm) with a spectral point spacing of 0.0068 cm. Twenty-nine datasets were collected at temperatures between 300 and 1300 K (±0.82 % average uncertainty) and pressures ranging from 20 to 600 Torr (±0.25 %) with an average residual absorbance noise of 8.0E-4 across the spectrum for all measurements. We fit measurements using a quadratic speed-dependent Voigt profile to determine 7088 absorption parameters for 3366 individual transitions found in HITRAN2020. These measurements build on the line strength, line center, self-broadening, and self-shift parameters determined in the Part I companion of this work. Here we measure air-broadened width (with temperature- and speed-dependence) and air pressure shift (with temperature-dependence) parameters. Various trends are explored for extrapolation to weak transitions that were not covered in this work. Improvements made in this work are predominantly due to the inclusion of air pressure shift temperature dependence values. In aggregate, these updates improved RMS absorbance error by a factor of 4.2 on average, and the remaining residual is predominantly spectral noise. This updated database improves high-temperature spectroscopic knowledge across the 6600-7650 cm region of HO absorption.

中文翻译：

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使用双梳光谱从 300 到 1300 K 的水蒸气吸收数据库第二部分：空气加宽的 H2O，6600 到 7650 cm−1


我们提出了空气中 2% H2O（天然同位素丰度为 99.7% H2O）的宽带双频梳激光吸收测量，测量范围为 6600 至 7650 cm（1307–1515 nm），光谱点间距为 0.0068 cm。在 300 至 1300 K 的温度（±0.82% 平均不确定性）和 20 至 600 Torr（±0.25%）的压力下收集了 29 个数据集，所有测量的整个光谱的平均残余吸收噪声为 8.0E-4 。我们使用二次速度相关的 Voigt 曲线拟合测量结果，以确定 HITRAN2020 中发现的 3366 个单独跃迁的 7088 个吸收参数。这些测量建立在本工作第一部分同伴中确定的线强度、线中心、自展宽和自移位参数的基础上。在这里，我们测量空气加宽宽度（与温度和速度相关）和气压变化（与温度相关）参数。探索了各种趋势，以推断本工作中未涵盖的弱转变。这项工作中所做的改进主要是由于包含了气压变化温度依赖性值。总的来说，这些更新将 RMS 吸光度误差平均改善了 4.2 倍，剩余的残留主要是光谱噪声。这个更新的数据库改进了 H2O 吸收 6600-7650 cm 区域的高温光谱知识。