Figure 2. Validation Experiments of White Light From Black Carbon (BC) in Human Brain Tissue.

A, Emission fingerprints of BC, reference conductive carbon black particles (CCB), and 2-photon autofluorescence (TPAF) were measured for the brain tissue under femtosecond-pulsed illumination. B, Image in XY-projection acquired throughout sectioning of brain tissue in the z-direction, showing a BC particle (white, indicated by white arrowheads) in the corresponding orthogonal XZ-projection and YZ-projection inside the tissue (green, autofluorescence; red, second harmonic generation). C, Lifetime measurements show the temporal response of identified BC, reference CCB particles, and TPAF. IRF indicates instrument response function.