Photo-Luminescence Dynamics of Ionic Liquids Composed of the Dicyanoaurate(I) Anion

2019 ◽  
Vol 72 (2) ◽  
pp. 42 ◽  
Author(s):  
Yoshifumi Kimura ◽  
Takamitsu Narita ◽  
Saki Tanaka ◽  
Mitsuhiro Taniguchi ◽  
Kaori Fujii ◽  
...  
Keyword(s):  
Ionic Liquids ◽  
Photo Luminescence ◽  
Wavelength Dependence ◽  
Structural Heterogeneity ◽  
Peak Shift ◽  
Peak Position ◽  
Time Profile ◽  
Excitation Wavelength ◽  
Time Resolved ◽  
The Difference

Time-resolved luminescent spectra of ionic liquids of 1-butyl-3-methylimidazolium dicyanoaurate ([C4mim][Au(CN)2]) and N-butyl-N-methylpyrrolidinium dicyanoaurate ([P14][Au(CN)2]) at different excitation wavelengths (310 and 340nm) were measured using a streak camera. Immediately after photoexcitation, an intense luminescence band appeared at ~380nm that rapidly decayed with a time constant of 31 ps for [C4mim][Au(CN)2] and 71 ps for [P14][Au(CN)2]. With the decay of this band, another luminescent band appeared at ~460nm that slowly decayed (88ns for [C4mim][Au(CN)2] and 1.2μs for [P14][Au(CN)2]). The peak position of this second band shifted to a longer wavelength over time for both ionic liquids. The time profile of the peak showed a multi-exponential decay and depended on the excitation wavelength and the cation species. The peak shift is discussed in terms of the aggregation of anions. The excitation wavelength dependence was supposed to reflect the distribution of the larger oligomer in the ground state and the structural heterogeneity of the ionic liquids. The difference as a result of the cation is discussed in relation to the viscosity and the structure of the ionic liquids.

scholarly journals The effect of structural heterogeneity upon the microviscosity of ionic liquids

2020 ◽  
Vol 11 (24) ◽  
pp. 6121-6133 ◽  
Author(s):  
Ryan Clark ◽  
Mohd A. Nawawi ◽  
Ana Dobre ◽  
David Pugh ◽  
Qingshan Liu ◽  
...  
Keyword(s):  
Ionic Liquid ◽  
Ionic Liquids ◽  
Bulk Viscosity ◽  
Structural Heterogeneity ◽  
Molecular Rotors ◽  
Complex Relationship ◽  
Molecular Rotor ◽  
Time Resolved Fluorescence ◽  
Time Resolved

The behaviour of two molecular rotors have been studied in various ionic liquids. Time resolved fluorescence shows a complex relationship between the bulk viscosity of the ionic liquid and microstructure of solvent around each molecular rotor.

Comparison between pyrrolidinium-based and imidazolium-based dicationic ionic liquids: intermolecular interaction, structural organization, and solute dynamics

2021 ◽  
Vol 23 (37) ◽  
pp. 21029-21041
Author(s):  
Amita Mahapatra ◽  
Manjari Chakraborty ◽  
Sahadev Barik ◽  
Moloy Sarkar
Keyword(s):  
Ionic Liquids ◽  
Steady State ◽  
Nmr Spectroscopy ◽  
Intermolecular Interaction ◽  
Structural Organization ◽  
Time Resolved Fluorescence ◽  
Time Resolved ◽  
Dicationic Ionic Liquids ◽  
The Difference ◽  
Solute Dynamics

This work investigates the difference in the microscopic behaviour of imidazolium and pyrrolidinium based ILs employing combined steady state and time-resolved fluorescence, EPR and NMR spectroscopy.

Exciton localization behaviour in different well width undoped GaN/Al0.07Ga0.93N nanostructures

2007 ◽  
Vol 15 (3) ◽  
Author(s):  
M. Sabooni ◽  
M. Esmaeili ◽  
H. Haratizadeh ◽  
B. Monemar ◽  
P. Paskov ◽  
...  
Keyword(s):  
Quantum Wells ◽  
Decay Time ◽  
Photo Luminescence ◽  
Peak Position ◽  
Emission Peak ◽  
Time Resolved ◽  
Exciton Localization ◽  
Decay Times ◽  
Detection Energy ◽  
Hole Transition

AbstractWe report results from optical spectroscopy such as photoluminescence (PL) and time resolved photo-luminescence (TRPL) techniques from different well width MOCVD grown GaN/Al0.07Ga0.93N MQW samples. There is evidence of localization at low temperature in all samples. The decay time of all samples becomes non-exponential when the detection energy is increased with respect to the peak of the emission. Localization of carriers (excitons) is demonstrated by the “S-shape” dependences of the PL peak energies on the temperature. The time-resolved PL spectra of the 3-nm well multi quantum wells reveal that the spectral peak position shifts toward lower energies as the decay time increases and becomes red-shifted at longer decay times. There is a gradient in the PL decay time across the emission peak profile, so that the PL process at low temperatures is a free electron-localized hole transition.

Fluorescence, Phosphorescence, and Delayed Fluorescence of Benzil in Imidazolium Ionic Liquids

2012 ◽  
Vol 65 (9) ◽  
pp. 1291 ◽  
Author(s):  
Dinesh Chandra Khara ◽  
Anunay Samanta
Keyword(s):  
Ionic Liquids ◽  
Room Temperature ◽  
Emission Spectra ◽  
Wavelength Dependence ◽  
Delayed Fluorescence ◽  
Excitation Wavelength ◽  
Imidazolium Ionic Liquids ◽  
Thermally Activated ◽  
Phosphorescence At Room Temperature ◽  
The Media

Temperature dependence of the emission behaviour of benzil has been studied in three imidazolium ionic liquids differing in their polarity and viscosity. Room temperature absorption and steady-state emission spectra suggest that the ground and excited state conformers of benzil in ionic liquids are similar to those in conventional organic solvents. The non-degassed solutions of benzil in ionic liquids show phosphorescence at room temperature in contrast to conventional solvents where phosphorescence is commonly observed in degassed conditions. This study reveals that a thermally activated reverse intersystem crossing (T1↝S1) process is responsible for the drastic change in phosphorescence intensity with temperature in ionic liquids. The rate constant () of this process is found to be dependent on the polarity of the media and is 5 times higher in most polar ionic liquids. The evidence of the presence of multiple conformers of benzil in frozen conditions is obtained from the excitation wavelength dependence of the phosphorescence spectra.

Luminescence Properties of Thin-Film SrS:Cu Phosphors for Electroluminescent Displays

1998 ◽  
Vol 508 ◽  
Author(s):  
T.C. Jones ◽  
W. Park ◽  
E. Mohammed ◽  
B.K. Wagner ◽  
C.J. Summers ◽  
...  
Keyword(s):  
Thin Film ◽  
Fine Structure ◽  
Peak Shift ◽  
Peak Position ◽  
Teller Effect ◽  
Field Analysis ◽  
Excitation Wavelength ◽  
Jahn Teller ◽  
Jahn Teller Effect ◽  
Rigorous Treatment

AbstractThe origin of the electronic fine structure in thin-film SrS:Cu has been interpreted in terms of the several possible perturbations including spin-obit coupling, the Jahn-Teller effect and low symmetry splittings. Photoluminescence excitation measurements showed that the peak position of the excitation bands were independent of temperature suggesting that the electronic fine structure in our system was not due to the Jahn-Teller effect. Selective excitation measurements revealed that no peak shift occurs with changing excitation wavelength, indicating that Cu+ pairs or aggregates and Cu+-defect coupled centers were not existent in our system. Finally, several models were proposed for off-center displacements of Cu in SrS, since a rigorous treatment of these displacements is difficult. Both the tetragonal and trigonal distortion models for a <111> displacement yielded reasonable distortions parameters of 0. 16Å and 0.11Å, respectively. However, crystal field analysis showed that a <110> displacement was more likely since the energy level splitting scheme more closely resembled the observed data.

scholarly journals The peak shift and evolution of upconversion luminescence from CsPbBr3nanocrystals under femtosecond laser excitation

RSC Advances ◽  
2017 ◽  
Vol 7 (57) ◽  
pp. 35757-35764 ◽  
Author(s):  
Qiuju Han ◽  
Wenzhi Wu ◽  
Weilong Liu ◽  
Yanqiang Yang
Keyword(s):  
Excited State ◽  
Femtosecond Laser ◽  
Laser Excitation ◽  
Upconversion Luminescence ◽  
Peak Shift ◽  
Peak Position ◽  
Red Shift ◽  
Time Resolved ◽  
Pl Spectrum

Compared with normal PL, a red shift of upconversion PL spectrum is observed. Time-resolved PL and TA spectroscopies show FWHM and peak position are changed at various times, which suggest the existence of more than single excited state.

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