NIR to Vis-NIR up-conversion and X-ray excited emission of Er doped high Z BiOCl

Herein, we investigate the emission properties of Er - BiOCl in the range of ∼500 to 1700 nm under down - (488 and 973 nm) and NIR (telecom - wavelength at ~1500 nm) up - conversion excitation as well high energy X-ray excitation. The dependencies of red (~670 nm) and NIR (~800 nm) to green emission (~543 nm) ratio with Er concentration, excitation mode and delay after laser pulse as well as the up - conversion excitation spectra and decays are analyzed in terms of competitive ground state absorption/excited state absorption and energy transfer up - conversion mechanisms. The CIE chromaticity diagram show single excitation (~1500 nm), delay induced emission color change from yellowish green (delay of 0.001 ms) to reddish orange (delay of 1 ms). The X-ray induced emission of Er - BiOCl presents an atypical red to green emission ratio that exceeds that measured under optical down - conversion excitation by a factor of 13. The potential of Er - BiOCl for optical /X-ray imaging applications is discussed.