Temperature dependence of the visible-near-infrared absorption spectrum of liquid water

Optical absorptivity spectra of ultrapure liquid water over the wavelength range from 550 to 900 nm and over the temperature range from similar to 15 to 60 degreesC are presented. The measured temperature dependence compares well with those reported by most previous workers. The linear dependence of the absorption spectrum on temperature is discussed in terms of structural changes occurring in liquid water as a function of temperature. The two-state, outer-neighbor bonding model of Robinson and co-workers is found to provide a good microscopic explanation of our data.