Spectroscopic, laser, and chi((3)) nonlinear optical properties of tetragonal PbWO(4), NaY(WO(4))(2), CaWO(4), and monoclinic CdWO(4) and ZnWO(4) were investigated. Particular attention was paid to Nd(3+)-doped and undoped PbWO(4) and NaY(WO(4))(2) crystals. Their absorption and luminescence intensity characteristics, including the peak cross sections of induced transitions, were determined. Pulsed and continuous-wave lasing in the two 4F(3/2)-->4I(11/2) and 4F(3/2)-->4I(13/2) channels was excited. For these five tungstates, highly efficient (greater than 50%) multiple Stokes generation and anti-Stokes picosecond generation were achieved. All the observed scattered laser components were identified. These results were analyzed and compared with spectroscopic data from spontaneous Raman scattering. A new crystalline Raman laser based on PbWO(4) was developed for the chi((3)) conversion frequency of 1-microm pump radiation to the first Stokes emission with efficiency up to 40%. We classify all the tungstates as promising media for lasers and neodymium-doped crystals for self-stimulated Raman scattering lasers.

Rare-earth-doped luminescent nanothermometers are not reliable as their emission spectra can be affected by numerous environmental and experimental factors.

Over the past decade, near-infrared (NIR)-emitting nanoparticles have increasingly been investigated in biomedical research for use as fl uorescent imaging probes. Here, high-quality water-dispersible core/shell/shell PbS/ CdS/ZnS quantum dots (hereafter QDs) as NIR imaging probes fabricated through a rapid, cost-effective microwave-assisted cation exchange procedure are reported. These QDs have proven to be water dispersible, stable, and are expected to be nontoxic, resulting from the growth of an outer ZnS shell and the simultaneous surface functionalization with mercaptopropionic acid ligands. Care is taken to design the emission wavelength of the QDs probe lying within the second biological window (1000-1350 nm), which leads to higher penetration depths because of the low extinction coeffi cient of biological tissues in this spectral range. Furthermore, their intense fl uorescence emission enables to follow the real-time evolution of QD biodistribution among different organs of living mice, after low-dose intravenous administration. In this paper, QD platform has proven to be capable (ex vivo and in vitro) of high-resolution thermal sensing in the physiological temperature range. The investigation, together with the lack of noticeable toxicity from these PbS/CdS/ZnS QDs after preliminary studies, paves the way for their use as outstanding multifunctional probes both for in vitro and in vivo applications in biomedicine.

The potential use of CdTe quantum dots as luminescence nano-probes for lifetime fluorescence nano-thermometry is demonstrated. The maximum thermal sensitivity achievable is strongly dependent on the quantum dot size. For the smallest sizes (close to 1 nm) the lifetime thermal sensitivity overcomes those of conventional nano-probes used in fluorescence lifetime thermometry.

The lattice location of three rare-earth ions (Pr3+, Ho3+, Yb3+) in LiNbO3 is investigated using Rutherford backscattering spectrometry/channeling techniques. All of them are found to occupy the Li+ octahedron but shifted from the Li+ regular position by different amounts (−0.45 Å for Pr3+, −0.38 Å for Ho3+, and −0.3 Å for Yb3+) as previously reported for other rare-earth ions. The amount of displacement is directly related to the variation of the ionic radius of the rare-earth ion, oppositely to transition metal ions which are not shifted. A simple model based on electronic configuration is given to account for this behavior.