Strek W, Tomala R, Marciniak L, Lukaszewicz M, Cichy B, Stefanski M, Hreniak D, Kedziorski A, Krosnicki M, Seijo L
Institute of Low Temperature and Structure Research, Polish Academy of Sciences, Wroclaw, 50-433, Poland.
Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University, Toruń, 87-100, Poland.
Phys Chem Chem Phys. 2016 Oct 12;18(40):27921-27927. doi: 10.1039/c6cp04904d.
The laser induced white emission (LIWE) from SrCeO nanocrystals 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 SrCeO nanocrystals 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 Ce and Ce ions that allow for the intervalence charge transfer (IVCT) emission transitions in the white light range. A strong decrease of absorption band intensity of SrCeO with increasing LIWE intensity confirms the creation of (Ce, Ce) pairs.
研究了用聚焦红外激光束照射SrCeO纳米晶体时产生的激光诱导白色发射（LIWE）。观察到这是一种阈值现象，其强度随激发功率密度呈指数增加。在紫外范围内的双激光束同时激发下对该过程进行了研究，这导致在可见光范围内产生斯托克斯发射，在红外范围内产生反斯托克斯LIWE。随着LIWE强度的增加，斯托克斯发射强度强烈下降。LIWE伴随着取决于激光激发密度的有效光电流产生，随后是多光子吸收和电离过程。光阻抗测量表明，在LIWE过程中，SrCeO纳米晶体的介电常数急剧增加了几个数量级，表现出类似金属的行为。LIWE的机制包括多光子吸收和电离，这导致形成一对耦合的Ce和Ce离子对，从而允许在白光范围内进行价间电荷转移（IVCT）发射跃迁。随着LIWE强度的增加，SrCeO吸收带强度的强烈下降证实了（Ce，Ce）对的形成。
