Excited-state absorption of excitons and biexcitons confined in CuCl quantum dots

This study reports the first observation of the temporal evolution of the infrared transient absorption (IRTA) of CuCl quantum dots by means of tunable ultrafast pump-probe spectroscopy technique based on two optical parametric amplifiers (pulse width: 2 ps, repetition rate: 1 kHz). Results show that the IRTA originates not only from the excitons but also from the biexcitons confined in the quantum dots under high excitation intensities.