Optical study of terrylene molecules in crystalline biphenyl: effects of pressure and temperature on the luminescence spectra

Abstract

The photoluminescence spectra of terrylene guest molecules in polycrystalline biphenyl host were measured at various temperatures between 4.7 and 295 K under ambient pressure (1 atm) as well as under various pressures up to 4.4 kbar at 4.7 K and up to 4.9 kbar at 295 K. With increasing pressure, all four spectral peaks studied shift to the red. By elevating the temperature from 4.7 to 295 K at 1 atm, the most intense peak at 17,220 cm⁻¹ first shifts slightly to the red, but at ∼40 K begins to shift to the blue. Comparison of the temperature and pressure shifts for this peak reveals that its temperature shift is mainly determined by the thermal expansion of the host crystal rather than by the change in the electron–phonon coupling with temperature.

Keywords:

• Terrylene impurity molecules
• Biphenyl host crystal
• Luminescence spectra
• Pressure and temperature effects

Acknowledgements

The authors are grateful to the Estonian Science Foundation for financial support via Grant Nos. 5544 and 6543.