Schematic diagram (left) and photograph (right) of the newly developed high-sensitivity transient absorption microscope. Credit: Toru Kondo How do photosynthetic organisms harvest light so efficiently? To help answer this question, researchers have developed an ultrafast transient absorption microscope with sensitivity approaching the single-molecule level. Plants and photosynthetic bacteria have a wide variety of light-harvesting antennae in which pigment molecules are precisely arranged to utilize light energy efficiently. However, these molecular arrangements are not perfectly uniform and vary from particle to particle because of conformational distortions and fluctuations. Such structural variations are considered to perturb excited states and energy transfer processes triggered by light absorption.…