Photostimulated near-infrared persistent luminescence as a new optical read-out from Cr3+-doped LiGa5O8

Abstract

In conventional photostimulable storage phosphors, the optical information written by x-ray or ultraviolet irradiation is usually read out as a visible photostimulated luminescence (PSL) signal under the stimulation of a low-energy light with appropriate wavelength. Unlike the transient PSL, here we report a new optical read-out form, photostimulated persistent luminescence (PSPL) in the near-infrared (NIR), from a Cr3+-doped LiGa5O8 NIR persistent phosphor exhibiting a super-long NIR persistent luminescence of more than 1,000 h. An intense PSPL signal peaking at 716 nm can be repeatedly obtained in a period of more than 1,000 h when an ultraviolet-light (250–360 nm) pre-irradiated LiGa5O8:Cr3+ phosphor is repeatedly stimulated with a visible light or a NIR light. The LiGa5O8:Cr3+ phosphor has promising applications in optical information storage, night-vision surveillance, and in vivo bio-imaging.

In Vivo Repeatedly Charging Near‐Infrared‐Emitting Mesoporous SiO2/ZnGa2O4:Cr3+ Persistent Luminescence Nanocomposites

“…[1–3] The temporal separation of excitation and afterglow properties of these persistent phosphors makes them ideal as in vivo optical imaging contrast reagents. [4–6] Until now, persistent luminescence has relied on short-wavelength excitation (e.g., ultraviolet light) which has rather limited tissue-penetration depth.…”

“…[7–10] To address this problem, a NIR-light-stimulated PL mechanism was proposed in LiGa 5 O 8 :Cr 3+ , to release energy trapped in deeper energy levels of the phosphor, but in this case, the energy must be precharged by UV-light and the photostimulated emission continues to weaken after each cycle of photostimulation and will finally become extinguished. [3,11] Very recently, the PL phosphor, ZnGa 2 O 4 :Cr 3+ (ZGC), was found to be activatable by using tissue-penetrable red light, which means that energy can be recharged and NIR PL imaging is no longer limited by the luminescence-decay life-time of the phosphor. [12] Thus ZGC is arguably the optimal rechargeable NIR persistent emitting phosphor reported to date.…”

“…To make such NIR-persistent phosphors bulk crystal requires temperatures >750 °C in traditional solid-state annealing reactions. [1,7,13] Moreover, to convert such bulk crystal into nanoparticles that are sufficiently disperse for biological applications, certain tedious physical treatments such as grinding [2,3,14,15] or laser ablation [16] must be utilized. The afforded products are generally highly heterogeneous and suffer from severe agglomeration.…”

Tailoring of the trap distribution and crystal field in Cr3+-doped non-gallate phosphors with near-infrared long-persistence phosphorescence

“…6 Such biomarkers are expected to enable advanced optical imaging with high-resolution and minimal excitation disturbance to experimentally assess structural and functional processes in cells, tissues and other complexes in in vivo systems. 7 Over the past few years, substantial strides have been made in the research and development of LPPs for NIR wavelengths, [8][9][10][11][12][13][14][15][16][17][18][19][20] with the main focus of the research being Mn 2+ , Mn 4+ and Cr 3+ -activated NIR LPPs. In 2007, Chermont et al proposed a novel bio-imaging method using red-to-NIR persistent nanoparticles, Ca 0.2 Zn 0.9 Mg 0.9 Si 2 O 6 : Eu 2+ , Dy 3+ , Mn 2+ , and opened a new application area for NIR LPPs.…”

X-ray micro-modulated luminescence tomography (XMLT)

“…Unlike conventional nanoparticle probes, LiGa 5 O 8 :Cr 3+ nanoparticles were recently synthesized to facilitate the luminescence energy storage with xray pre-excitation and subsequently stimulated luminescence emission by visible/nearinfrared (NIR) light [17,18]. LiGa 5 O 8 :Cr 3+ nanoparticles are synthesized using a sol-gel method with lithium nitrate, gallium nitrate and chromium nitrate as precursors, followed by calcination and wet mechanical grinding.…”