This temporary Expression of Concern relates to the above article. Concerns have been brought to the journal's attention regarding unusual similarities between the results presented in the above paper (paragraph 3.5) and those in the paper Opt. Quant. Electron. Vol. 49, 398 (2017). doi: 10.1007/s11082-017-1236-8, which concerns another material, specifically nanocrystalline thin films of 4-tricyanovinyl-N,N-diethylaniline irradiated with X-rays. The journal editors are reviewing the article, including contacting the authors, in accordance with Committee on Publication Ethics (COPE) guidelines and Ukrainian Journal of Physical Optics' ethical policies. The Expression of Concern will stay attached to the article until the investigation is complete. If the editors conclude, they will take any necessary actions, i.e., a formal retraction, correction, or addendum. If the editors determine they cannot reach a satisfactory conclusion with the available information, the Expression of Concern will remain as a final notice.

Editor-in-Chief: Prof.R.Vlokh

Available online : 27.01.2026
Ukr. J. Phys. Opt. Vol. 27, Issue 1 , p. 01121 (2026). doi:10.3116/16091833/Ukr.J.Phys.Opt.2026.01121