We investigated the continuum absorption of water vapour diluted in nitrogen, oxygen and air in the range of the pure rotational band of the water molecule (50-500 cm⁻¹). Spectra recordings were performed at room temperature with a Fourier transform spectrometer associated to a 151-m multipass gas cell located at the AILES beamline of SOLEIL synchrotron facility. The study includes the first laboratory measurements in the wide 90-330 cm⁻¹ interval. Tests of the baseline stability, crucial for the continuum determination, are reported together with the expected pressure dependences of the continuum absorption, measured over different pressure ramps. Retrieved foreign-continuum cross-sections are found in good agreement with literature values available in the lower and upper parts of the studied frequency range. The reported results validate the MT_CKD foreign-continuum empirical model, widely used in atmospheric applications, even if some overestimation of the MT_CKD values is noted in the centre of the band where experimental data were absent.

我们研究了在水分子的纯旋转带（50-500 cm ^-1）范围内被氮气，氧气和空气稀释的水蒸气的连续吸收。光谱记录是在室温下使用傅立叶变换光谱仪进行的，该光谱仪与位于SOLEIL同步加速器设施的AILES光束线上的151米多通气室相关联。该研究包括在90-330 cm ^-1宽的范围内进行的首次实验室测量间隔。报告了对于连续性测定至关重要的基线稳定性测试，以及在不同压力梯度下测得的连续吸收的预期压力依赖性。检索到的外国连续谱横截面与所研究频率范围的下部和上部可获得的文献值非常吻合。报告的结果验证了MT_CKD外部连续经验模型，该模型在大气应用中得到了广泛使用，即使在没有实验数据的频带中心发现了MT_CKD值的一些高估也是如此。