## 1 Introduction
Regarding H\({}_{2}\)O line data, collisional broadening coefficients are specifically required for spectroscopic measurements, e.g., those based on dTDLAS and similar spectroscopic techniques, where the absorption line has to be modeled (due to potential variations in the gas pressure, temperature or matrix during the measurements), e.g., with a Voigt profile. These line data, i.e., collisional broadening coefficients as well as line strengths, are usually taken from spectroscopic databases such as HITRAN [26] and GEISA [27]. In fact, these databases have large amounts of line data for a broad range of molecules. However, information on the traceability of the line data to the SI units and assessments of uncertainties following the guide to the expression of uncertainty in measurement (GUM) [28] are almost never provided [29]. However, there is a call for new and improved SI-traceable line data for specific applications, e.g., in atmospheric H\({}_{2}\)O measurements. A few studies did already focus on the measurement of SI-traceable line data and the evaluation of the associated uncertainties following GUM principles [10; 18]. For the majority of laser hygrometers where the data evaluation concept does not require modeling of the absorption line employing line data, tedious pressure, temperature- and matrix-dependent calibration of the instrument is required. These sometimes difficult and complex calibration procedures can be avoided if accurate and reliable line data are used to fit the absorption line to determine the amount of water, i.e., in dTDLAS-OGS instruments [3; 22]. Fitting the absorption line with accurate collisional broadening coefficients can significantly increase the speed of measurements due to a reduced number of fitting parameters, particularly important in the field where small variations in gas concentrations need to be captured as fast as possible, and the repeatability and reproducibility of the corresponding concentration results. The necessity of reliable collisional broadening coefficients (to improve concentration measurements and results) has also been demonstrated in a variety of applications [3; 7; 9; 11; 14; 22]. Apart from dTDLAS, a variety of laser spectrometers have been employed aiming for high-accuracy H\({}_{2}\)O measurements, e.g., comparing results to a primary trace-moisture standard [30], performing absolute measurements of water vapor densities reaching an overall uncertainty of 0.8% [31], utilizing a frequency-stabilized cavity ring-down spectroscopy spectrometer for high-precision measurements of trace water vapor concentration and reaching a minimum detection of water vapor concentration of 0.7 ppb [32], applying wavelength modulation spectroscopy for H\({}_{2}\)O detection in combustion gases and achieving a precision of 2.1% [33], performing improved measurements of water vapor in the upper troposphere and lower stratosphere using direct absorption spectroscopy and comparingthe results to other instruments [34] to understand discrepancies and measurements of spectral parameters of water-vapor transitions [35; 36; 37]. In this paper, we report improved and metrology-compatible collisional line data (i.e., self- and air broadening coefficients and their temperature dependence exponents) for the H\({}_{2}\)O line at 7299.43 cm\({}^{-1}\) (000-101, 110-211) often used in atmospheric H\({}_{2}\)O measurements [3; 5; 6; 8; 9; 11; 12; 13; 14; 15; 16]. A laser spectroscopic system for measurements of H\({}_{2}\)O self-broadening coefficient and temperature dependences is presented, specially designed to address the difficulties in preparing and handling pure water vapor samples at between room temperature and 100 \({}^{\circ}\)C where the exponential dependence of the water vapor saturation pressure on temperature makes it difficult to study self-broadening. For air broadening and temperature dependence measurements, separate gas cells (and thus modified spectroscopic systems) are used.