Long-term luminescence in organic liquids at low temperatures

Abstract

We report the results of an experimental study on the temporal and spectral response of organic liquids luminescence excited by UV radiation at liquid-nitrogen temperature. The afterglow at liquid-nitrogen temperature was detected with a decay time of the order of 1000 ms. We have revealed that the afterglow appears at a definite temperature of about 80 K.

Phosphorescence in cooled organic materials—temporal kinetics and spectral memory effect

“…Below we present the results of further studies initiated in works series [7][8][9][10]. To study the spectral properties of organic substances cooled up to the liquid nitrogen temperature, we created a laboratory setup described in [8][9][10].…”

“…This installation makes it possible to study the phosphorescence of matrices cooled to cryogenic temperature. In the experiments described in [8][9][10], the 'photon flame' effect previously discovered in [11] was additionally investigated, which consists in long-term phosphorescence from 1 to 12 s when a nano-structured matrices based on artificial opal SiO 2 was excited by a ruby laser single-mode giant impulse radiation.…”

“…In [10], studies of the temporal and spectral characteristics of ethanol C 2 H 5 OH, isopropyl CH 3 CH(OH)CH 3 , and benzyl C 6 H 5 CH 2 OH alcohols. The samples were cooled to cryogenic temperatures and their phosphorescence spectra were excited for 10 s by ultraviolet radiation from a mercury lamp.…”

“…The samples were cooled to cryogenic temperatures and their phosphorescence spectra were excited for 10 s by ultraviolet radiation from a mercury lamp. An analysis of the data obtained in [7][8][9][10] and literature [12][13][14][15][16][17][18] allows us to conclude that the phosphorescence spectra of various substances cooled up to cryogenic temperatures can degrade over time. In addition the spectrum itself can 'shift' depending on the matrix in which is 'placed' phosphorescent molecule or atom.…”

“…The long-term phosphorescence effect is usually associated with a nonradiative transition in the triplet radiation scheme [10][11][12][13][14][15][16][17]. At the same time, the authors of this article consider other possible models for describing this phenomenon.…”