Easily ignored interference light from the second order diffraction of the excitation grating in a xenon lamp-based spectrometer

Abstract

Due to the diffraction of light by gratings, use of optical filters is typically recommended in the emission exit in xenon lamp-based spectrofluorometer, especially for turbid samples. However, such diffraction also exists in the excitation, but is typically ignored. In this work, we demonstrated that the higher order diffraction of gratings in the excitation exit in the front of xenon lamp could cause real light, which could interference the fluorescence detection for NIR-emitting fluorophores. Besides, such interference light may also result in debated upconversion results in nowadays' nano-fluorophores. Overall, we wanted to call attention for the use of optical filters in the excitation exit to exclude potential biased results in fluorescence-related research, such as NIR-emissive fluorophores and long wavelength photocatalysis.