Negative Absorption Peaks in Ultraviolet-Visible Spectrum of Water

Ultraviolet-visible absorption spectra exhibit absorption that is under the base line, which we propose is negative absorption (NA) or negative absorption emission (NAE). The UV-visible NAE of water, ethanol, and chloroform was illustrated by transmittance curves, reflectivity curves, and fluorescence excitation/emission spectra. To explain this phenomenon, the TD_DFT theory was used to calculate the emission states of the samples. A laser transmission experiment confirmed the NAE phenomenon. It was concluded that NAE was a type of emission produced by the sample. The NAE of water has significant implications for life on earth, which will interest researchers in physics, chemistry, and biology.