Optical spectroscopy used is to develop luminescence materials based on their photoluminescence. Upconversion phosphor materials are attracting considerable attention for their possible applications in solar cells with improved efficiency, nanomaterials for bio-imaging, lasers and novel display technologies. Upconversion materials (for different type of samples, solids, liquids, suspensions and thin films), usually consisting of crystals/ powders/ particles doped with lanthanide ions, can convert low-energy incident radiation into higher energy emitted radiation.

The modular spectrofluorometer Fluorolog-3 consists of single-grating monochromators in excitation and emission positions, and red-sensitive photomultiplier. Fluorolog-3 spectrofluorometer is compact with fiber optic instruments for UV (377nm), VIS (529nm), and NIR (980nm) measurements in the 200-1500 nm range. We investigate the excitation/emission/decay characteristics of rare earth-doped phosphors materials, for NIR to visible and UV upconversion. The upconversion mechanisms were determined for the first time by means of in depth steady-state and time-resolved spectroscopic investigations.

• The targeted key features of Fluorolog-3 are:
• Applications adaptability;
• Performance versatility (easy translation from UV-VIS (200-850 nm) to near-infrared (NIR 850-1500 nm) in luminescence detection;
• Mobility of samples;
• Modularity (adding different add-on modules such as fiber optic extension can extend the functionality and performance of the system).

• Relevant publications:
• I. Porosnicu, C. Colbea, F. Baiasu, M. Lungu, M. C. Istrate, D. Avram, C. Tiseanu "A sensitive near infrared to near-infrared luminescence nanothermometer based on triple doped Ln -Y2O3" Methods and Applications in Fluorescence (2020), 8, 035005.
  https://doi.org/10.1088/2050-6120/ab8c20
• D. Avram, C. Colbea, M. Florea, C. Tiseanu "Highly-sensitive near infrared luminescent nanothermometers based on binary mixture" Journal of Alloys and Compounds (2019), 785, 250-259.
  https://doi.org/10.1016/j.jallcom.2019.01.162
• D. Avram, I. Tiseanu, B. S. Vasile, M. Florea, C. Tiseanu "Near infrared emission properties of Er doped cubic sesquioxides in the second/third biological windows" Sci. Rep. (2018) 8 (1), 18033.
  https://doi.org/10.1038/s41598-018-36639-y