Sub-percent accuracy for the intensity of a near-infrared water line at 10,670 cm−1: experiment and analysis.

Laser measurements of the intensity of (201) 3 22 − (000) 2 21 near-infrared water absorption line at 10,670.1 cm − 1 are made using three different Herriott cells. These measurements determine the line intensity with an standard deviation below of 0.3% by consideration of the new geometrically derived formula for the optical path length without approximations. This determination together with the current accepted value lead to an overall uncertainty of 0.7% of the experimentally assessed line intensity which is compared with previous ab initio predictions. It is found that steady improvements in both the dipole moment surface (DMS) and the potential energy surface (PES) used in the theoretical studies lead to a systematically better agreement with the observation, with the most recent prediction agreeing closely with the experiment. [ABSTRACT FROM AUTHOR]