Near‐infrared Light Emission from Nanomolar‐level Singlet Molecular Oxygen Generated with an Ultra low Concentration Mixture of Hypochlorite and Hydrogen Peroxide

Abstract— We report the detection of a weak near‐infrared light emission originating from 8 nM singlet molecular oxygen (1O2) produced in a mixture of 1 mM hypochlorite (OC1‐) and 8 nM hydrogen peroxide (H2O2). The measurements were made with a highly sensitive detection system for ultraweak light emission in the 1.0‐1.5 μm wavelength region. The emission intensity exhibited linear dependence for H2O2 concentrations in the range of 8‐670 nM. The mixture containing a lower concentration (33 μM) of OCl‐ pseudocontinuously emitted near‐infrared light for 5 s. The rate constant for 1O2 production obtained from the kinetic analysis agrees with that previously reported. Our results demonstrate the possibility of measuring very low concentrations of 1O2 in a OCi‐/H2O2 mixture as well as 1O2 production in intact living systems.