Temperature sensing in Tb3+/Eu3+-based tetranuclear silsesquioxane cages with tunable emission

Tetranuclear silsesquioxane cages with tunable thermosensitive Tb3+-to-Eu3+ energy transfer were used for temperature sensing based on the Tb3+-to-Eu3+ emission intensity ratio (LIR) with excellent linearity and sensitivity.

1.5 μm photoluminescence and upconversion photoluminescence in GeGaAsS:Er chalcogenide glass

The paper reports on ≈1.5 μm Stokes photoluminescence (PL) emission and upconversion photoluminescence (UCPL) emission in the visible and near-infrared spectral region in Er3+-doped Ge25Ga8As2S65 chalcogenide glasses at pumping wavelengths of 980 and 1550 nm. The ≈1.5 μm PL emission spectra are broadened with increasing concentration of Er ions which is discussed in terms of radiation trapping and UCPL dynamics affecting the Er3+: 4I13/2 level lifetime. The UCPL emission was observed at ≈530, ≈550, ≈660, ≈810 and ≈990 nm and its overall intensity as well as red-to-green UCPL emission intensity ratio increases with increasing Er concentration. To explore the UCPL dynamics we measured double logarithmic dependency of green (≈550 nm) and red (≈660 nm) UCPL emission versus pump power at pumping wavelength of 975 nm. Moreover, we measured quadrature frequency resolved spectroscopy (QFRS) on green UCPL emission (≈550 nm) using 975 nm pumping wavelength and various excitation powers. The QFRS spectra on green UCPL were analyzed in term of QFRS transfer function for three-level model from which we deduced energy transfer upconversion rate w11 (s−1) originating from Er3+: 4I11/2, 4I11/2→4F7/2, 4I15/2 transitions.

Luminescent molecular thermometers for the ratiometric sensing of intracellular temperature

Recently, numerous luminescent molecular thermometers that exhibit temperature-dependent emission properties have been developed to measure the temperatures of tiny spaces. Intracellular temperature is the most interesting and exciting applications of luminescent molecular thermometers because this temperature is assumed to be correlated with all cell events, such as cell division, gene expression, enzyme reaction, metabolism, and pathogenesis. Among the various types of temperature-dependent emission parameters of luminescent molecular thermometers, the emission intensity ratio at two different wavelengths is suitable for accurate and accessible intracellular temperature measurements. In this review article, luminescent molecular thermometers that exhibit a temperature-dependent emission intensity ratio in living cells are summarized, and current progress in intracellular thermometry is outlined.

A simple process step for tuning the optical emission and ultraviolet photosensing properties of sol–gel ZnO film

An enhanced UV/VIS emission intensity ratio and UV photoresponse have been evidenced in the rapidly cooled sol–gel ZnO films.

Aggregation enhanced excimer emission (AEEE) with efficient blue emission based on pyrene dendrimers

A series of fluorescent dendrimers with pyrene moieties exhibited aggregation enhanced excimer emission (AEEE). Increases in the dendrimer generation caused emission at 480 nm with a high excimer/monomer emission intensity ratio.

Amine vapor responsive lanthanide complex entrapment: control of the ligand-to-metal and metal-to-metal energy transfer

We develop a luminescent platform based on Eu3+ and Tb3+ co-doped nanozeolite to realize the probing of amine solvents. Such a luminescence sensor can classify amine solvents and achieve an excellent fingerprint correlation between the amine solvents (with larger pKa values) and the emission intensity ratio (IEu/ITb), which is ratiometric.

Optimization of Carrier Distributions in Periodic Gain Structures toward Blue VCSELs

ABSTRACTWe have fabricated light emitting diodes (LEDs) in which two active regions separated with a Mg-doped GaN intermediate layer were placed in a single pn junction toward periodic gain structures (PGS) for blue vertical-cavity surface emitting lasers (VCSELs). By current density dependence on a emission intensity ratio from two different active regions, we obtained a very stable emission intensity ratio over 1 kA/cm2. This result is also confirmed with the simulation result. Furthermore, we found that the difference of emission wavelength affect the carrier injection and the emission intensity ratio. On the basis of this result, the optimized well-balanced Mg concentration in the intermediate layer for the two identical active regions were estimated approximately 5 x 1018 cm-3.