title: Broadband anti-Stokes white emission of Sr2CeO4nanocrystals induced by laser irradiation.
abstract: The laser induced white emission (LIWE) from Sr2CeO4nanocrystals upon irradiation with a focused IR laser beam was investigated. It was observed to be a threshold phenomenon with its intensity increasing exponentially with the excitation power density. This process was investigated under double laser beam simultaneous excitation in the UV range leading to Stokes emission in the visible range and in the IR range leading to anti-Stokes LIWE. With increasing LIWE intensity, the Stokes emission intensity strongly decreased. The LIWE is accompanied by efficient photocurrent generation depending on laser excitation density followed by multiphoton absorption and ionization processes. Photoimpedance measurements showed a sharp increase of the dielectric constant by several orders of magnitude in the Sr2CeO4nanocrystals during the LIWE process demonstrating a metallic-like behaviour. The mechanisms of LIWE include multiphoton absorption and ionization that lead to the creation of a coupled pair of Ce3+and Ce4+ions that allow for the intervalence charge transfer (IVCT) emission transitions in the white light range. A strong decrease of absorption band intensity of Sr2CeO4with increasing LIWE intensity confirms the creation of (Ce3+, Ce4+) pairs.
authors.affiliation: Institute of Low Temperature and Structure Research, Polish Academy of Sciences, Wroclaw, 50-433, Poland. r.tomala@int.pan.wroc.pl.
authors.forename: W
authors.initials: W
authors.lastname: Strek
authors.affiliation: Institute of Low Temperature and Structure Research, Polish Academy of Sciences, Wroclaw, 50-433, Poland. r.tomala@int.pan.wroc.pl.
authors.forename: R
authors.initials: R
authors.lastname: Tomala
authors.affiliation: Institute of Low Temperature and Structure Research, Polish Academy of Sciences, Wroclaw, 50-433, Poland. r.tomala@int.pan.wroc.pl.
authors.forename: L
authors.initials: L
authors.lastname: Marciniak
authors.affiliation: Institute of Low Temperature and Structure Research, Polish Academy of Sciences, Wroclaw, 50-433, Poland. r.tomala@int.pan.wroc.pl.
authors.forename: M
authors.initials: M
authors.lastname: Lukaszewicz
authors.affiliation: Institute of Low Temperature and Structure Research, Polish Academy of Sciences, Wroclaw, 50-433, Poland. r.tomala@int.pan.wroc.pl.
authors.forename: B
authors.initials: B
authors.lastname: Cichy
authors.affiliation: Institute of Low Temperature and Structure Research, Polish Academy of Sciences, Wroclaw, 50-433, Poland. r.tomala@int.pan.wroc.pl.
authors.forename: M
authors.initials: M
authors.lastname: Stefanski
authors.affiliation: Institute of Low Temperature and Structure Research, Polish Academy of Sciences, Wroclaw, 50-433, Poland. r.tomala@int.pan.wroc.pl.
authors.forename: D
authors.initials: D
authors.lastname: Hreniak
authors.affiliation: Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University, Toruń, 87-100, Poland.
authors.forename: A
authors.initials: A
authors.lastname: Kedziorski
authors.affiliation: Institute of Theoretical Physics and Astrophysics, University of Gdańsk, Gdańsk, 80-308, Poland.
authors.forename: M
authors.initials: M
authors.lastname: Krosnicki
authors.affiliation: Departamento de Quimica, Instituto Universitario de Ciencia de Materiales Nicolás Cabrera, and Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, 28049 Spain.
authors.forename: L
authors.identifier: http://orcid.org/0000-0002-0621-3694
authors.initials: L
authors.lastname: Seijo