Speaker: Pro. Robert Andrzej Tomala
Topic: Recent advances in the application of multiphoton ionization in rare earth doped phosphors
Date: April 18th, 2024 (Thursday)
Time: 11.00-12.00 a.m.
Venue: Room 428, School of Physics and Electronic Engineering
Sponsors: School of Physics and Electronic Engineering, Institute of Science and Technology
Biography:
He received a Master’s degree in computer-aided chemistry at the University of Wroclaw in 2012. Employed at the Institute of Low Temperature and Structure Research, Polish Academy of Sciences in Wroclaw since 2013, where obtained a PhD in chemical sciences in 2019. His scientific interests concern the synthesis and characterization of materials exhibit luminescence properties, such as nanocrystals, nano and micro ceramics and thin films. The main goal of his work is to investigate the optical and electrical properties of materials under excitation of high power density of laser beam and investigations of phosphors for general lighting. Co-author of more than 90 scientific publications published in international journals (H-index = 18) and five patents.
Abstract:
The interaction of rare earth doped inorganic matrix with high density beam of laser from infrared range lead to generation of efficient Stokes and anti-Stokes emission. It was found that under exceeding characteristic power threshold the intense broad band white emission could be observed. It increased with a simultaneous decreasing f-f transitions. In particular the effect of excitation power density and concentration of dopants ions were investigated. The intensity of white emission was characterized by exponential dependence on excitation power density. Moreover the white emission threshold decreased with excitation photon energy. The photocurrent accompanying white emission was measured. It increased exponentially with excitation power density. The mechanism of laser induced white emission is briefly discussed in terms of multi-photon ionization and intervalence charge transfer (IVCT) mechanism.
It was found that the effect can be applied for photocatalytic application. The efficient generation of hydrogen from water and alcohols like methanol and ethanol is observed. The obtained products were measured by mass spectrometry.