Theoretical study on photon emission statistics from single conjugated polymer molecules excited by laser pulses

In recent experiments, the signal-to-noise ratio and the photon pair correlation are measured simultaneously by improving the Hanbury-Brown and Twiss method. We show that judgement on whether the background noise obeys Poisson statistics or not is possible from the data of such measurements. If the background is subject to Poisson statistics, the results of both measurements enable to estimate the photon pair correlation in the absence of noise from that measured under background noise. The method is useful to remove the effect of background noise from the photon correlation measured by exciting multichromophore systems. We also show that the normalized photon pair correlation is not necessarily zero in the absence of background noise when single photon is emitted from multiple excitons as a result of the competition among the pair annihilation, and the unimolecular nonradiative and radiative processes.