  Recent reports of upconversion and white light emission from graphitic
particles warrant an explanation of the physics behind the process. We offer a
model, wherein the upconversion is facilitated by photo-induced electronic
structure modification allowing for multi-photon processes. As per the
prediction of the model, we experimentally show that graphite upconverts
infrared light centered around 1.31~$\mu$m to broadband white light centered
around 0.85 $\mu$m. Our results suggest that upconversion from shortwave
infrared ($\sim$3~$\mu$m) to visible region may be possible. Our experiments
show that the population dynamics of the electronic states involved in this
upconversion process occur in the timescale of milliseconds.
