Measurement of Photon Upconversion Luminescence Using RF-6000 Spectrofluorophotometer

Significance of the Topic

Photon upconversion (UC) enables the conversion of deep-penetrating near-infrared light into visible emission, offering new possibilities for non-invasive medical therapies, targeted drug delivery, and enhanced photovoltaic energy harvesting. Sensitive detection of weak UC signals is crucial for material development and quality control.

Aims and Study Overview

This work evaluates the Shimadzu RF-6000 spectrofluorophotometer’s ability to measure UC luminescence under low-intensity xenon excitation. Four rare-earth-doped oxide samples (CeO2 and Y2O3 matrices) synthesized via solid-phase sintering or liquid-phase methods were compared in terms of emission efficiency and spectral profile when excited at 900 nm.

Methodology and Instrumentation

Samples were placed in a powder holder and excited with a xenon lamp through an IR85N infrared-transmitting filter to block higher-order diffraction artifacts. Emission spectra from 500 nm to 700 nm were recorded with the RF-6000 using high detector sensitivity. Key settings included a 900 nm excitation wavelength, 0.5 nm data intervals, 60 nm/min scanning speed, and bandwidths of 20 nm (excitation) and 5 nm (emission).

Used Instrumentation

• Spectrofluorophotometer RF-6000 (Shimadzu)
• IR85N infrared-transmitting filter (HOYA Corporation)
• Xenon lamp excitation source
• Powder sample holder and diffraction-grating monochromator

Main Results and Discussion

All samples produced emission peaks near 560 nm and 670 nm, matching laser-excited reference spectra. Solid-phase sintered materials exhibited higher overall emission intensity than liquid-phase synthesized counterparts. Liquid-phase samples showed relatively stronger emission at shorter wavelengths, indicating that synthesis route can tune UC spectral ratios and luminous efficiency.

Benefits and Practical Applications

The RF-6000 allows UC measurements without specialized lasers, reducing cost and complexity. Its flexible filter configuration supports diverse excitation wavelengths, making it suitable for research, QA/QC, and development of UC materials for biomedical imaging, phototherapy, and solar energy conversion.

Future Trends and Potential Use

Advances in UC nanoparticles aim to lower excitation power requirements and enhance conversion efficiency under solar-like illumination. The RF-6000 provides a versatile platform for screening novel UC systems, including core–shell nanostructures and hybrid composites, for applications in theranostics, low-power displays, and next-generation photovoltaics.

Conclusion

The Shimadzu RF-6000 spectrofluorophotometer successfully detected UC emission from rare-earth-doped oxides under low-intensity excitation, differentiating synthesis-dependent spectral features. Its accessibility and sensitivity make it a valuable tool for advancing UC material research and application development.

References

• Koji Tomita, Journal of the Ceramic Society of Japan, 121(9):841-846, 2013.