Anomalous atmospheric absorption spectra due to water dimer

The anomalous atmospheric absorption spectra in the window wavelength region of 8–14 um have been suggested due to the water dimer. Based on our laboratory measurements, water continuum CO₂ laser absorption spectra and a resonance absorption line due to the weak local water vapor pure rotational transition have been reported. The equilibrium concentration of water dimers in the atmosphere, the electronic binding energy and the theoretical calculations for absorption attenuation have been obtained in agreement with published data.