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.

Upconversion luminescence properties of Li+-doped ZnWO4:Yb,Er

2008 ◽  
Vol 23 (8) ◽  
pp. 2078-2083 ◽  
Author(s):  
Xi-xian Luo ◽  
Wang-he Cao
Keyword(s):  
Liquid Phase ◽  
Calcination Temperature ◽  
Crystal Field ◽  
Lower Energy ◽  
Upconversion Luminescence ◽  
Peak Position ◽  
Liquid Phase Sintering ◽  
Red Shift ◽  
Luminescence Properties ◽  
Sintering Process

Upconversion luminescence (UPL) characteristics and effects of Li+ ion on the UPL of ZnWO4:Yb,Er polycrystalline phosphors were investigated. It was shown that introduction of Li+ ions could reduce the calcination temperature by about 200 °C and increase the crystallinity of ZnWO4:Yb,Er by a liquid-phase sintering process via formation of Li2WO4 and other intermediates. UPL efficiency is remarkably promoted by Li+ ions. Moreover, the UPL spectrum of Li+-doped ZnWO4:Yb,Er presents a red shift, and the strongest peak position shifts from 553 to 559 nm. These can be attributed to a shift in the 4f level barycenter to lower energy, which results from lowering of the symmetry of the crystal field around Er3+.

Upconversion luminescence of CdTe nanocrystals by use of near-infrared femtosecond laser excitation

2007 ◽  
Vol 32 (9) ◽  
pp. 1174 ◽  
Author(s):  
W. Z. Wu ◽  
Z. R. Zheng ◽  
W. L. Liu ◽  
J. P. Zhang ◽  
Y. X. Yan ◽  
...  
Keyword(s):  
Femtosecond Laser ◽  
Near Infrared ◽  
Laser Excitation ◽  
Upconversion Luminescence ◽  
Cdte Nanocrystals

scholarly journals Time-Resolved Resonance Raman Spectroscopy of Excited-State Porphyrins

1999 ◽  
Vol 19 (1-4) ◽  
pp. 271-274 ◽  
Author(s):  
S. E. J. Bell ◽  
J. H. Rice ◽  
J. J. McGarvey ◽  
R. E. Hester ◽  
J. N. Moore ◽  
...  
Keyword(s):  
Excited State ◽  
Excited States ◽  
Laser Excitation ◽  
Resonance Raman Spectroscopy ◽  
Resonance Raman ◽  
Laser Pulses ◽  
Significant Shift ◽  
Time Resolved ◽  
Two Component ◽  
Absorbance Difference

Time-resolved resonance Raman (TR3) and absorbance difference studies of the excited states of Cu(TPP) (TPP=5,10,15,20-tetraphenylporphyrin) have been carried out with < 10 ps times resolution in THF and pyridine solvents. In THF the distinctive transient Raman bands in the ν2 and ν4 regions, previously observed with ns laser pulses, grow in the first 55 ps before decaying in 100's of ps. The ∆A spectra also show biphasic decay. This behaviour is associated with attack by solvent on the 4-coordinate excited state to form the longer lived species observed in TR3 experiments.In pyridine two component decay is also observed but it is the shorter-lived species which gives the transient Raman bands seen previously with ns laser excitation. This state is different from that seen in THF. At 5 ps delay ν4 is broader than in the ground state and, more importantly, there is a significant shift in the two pyridine bands at ca. 1000 cm-1. This implies a significant involvement of the pyridine-based orbitals in the excited state.

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.

Structural and Optical Analysis of Eu3+ Doped BiVO4 Nanophosphor by Combustion Method

2015 ◽  
Vol 752-753 ◽  
pp. 272-276 ◽  
Author(s):  
R.S. Yadav ◽  
Y. Dwivedi ◽  
S.B. Rai
Keyword(s):  
Excited State ◽  
Relaxation Process ◽  
Emission Intensity ◽  
Spectroscopic Analysis ◽  
Laser Excitation ◽  
Wide Spectrum ◽  
Combustion Method ◽  
Annealed Sample ◽  
Optical Analysis ◽  
Time Resolved

Present article report synthesis and spectroscopic analysis of BiVO4 nanophosphor doped with trivalent Eu ions. It was observed that BiVO4 nanocrystals shows higher yield in comparison with the as-made nanocrystals on 266 nm laser excitation. On 266 nm excitation, emission composed of red dominated wide spectrum in the range of 400-950 nm was reported. Emission intensity enhanced five times on annealed sample than the counterpart. Time resolved analysis explores significant alteration in excited state relaxation process due to annealing. Detailed photo physics involved to improve optical emissions has also been explained.

scholarly journals Naphthalonitriles featuring efficient emission in solution and in the solid state

2020 ◽  
Vol 16 ◽  
pp. 2960-2970
Author(s):  
Sidharth Thulaseedharan Nair Sailaja ◽  
Iván Maisuls ◽  
Jutta Kösters ◽  
Alexander Hepp ◽  
Andreas Faust ◽  
...  
Keyword(s):  
Excited State ◽  
Photophysical Properties ◽  
Aqueous Media ◽  
Blue Emission ◽  
Blue Shift ◽  
Red Shift ◽  
Quantum Yields ◽  
Structure Property ◽  
Time Resolved ◽  
Deep Blue

In this work, a series of γ-substituted diphenylnaphthalonitriles were synthesized and characterized. They show efficient emission in solution and in the aggregated state and their environment responsiveness is based on having variable substituents at the para-position of the two phenyl moieties. The excited state properties were fully investigated in tetrahydrofuran (THF) solutions and in THF/H2O mixtures. The size of the aggregates in aqueous media were measured by dynamic light scattering (DLS). The steady-state and time-resolved photoluminescence spectroscopy studies revealed that all the molecules show intense fluorescence both in solution and in the aggregated state. In THF solutions, a blue emission was observed for the unsubstituted (H), methyl- (Me) and tert-butyl- (t-Bu) substituted γ-diphenylnaphthalonitriles, which can be attributed to a weak π-donor capability of these groups. On the other hand, the methoxy- (OMe), methylsulfanyl- (SMe) and dimethylamino- (NMe2) substituted compounds exhibit a progressive red-shift in emission compared to H, Me and t-Bu due to a growing π-electron donating capability. Interestingly, upon aggregation in water-containing media, H, Me and t-Bu show a slight red-shift of the emission and a blue-shift is observed for OMe, SMe and NMe2. The crystal structure of Me allowed a detailed discussion of the structure–property relationship. Clearly, N-containing substituents such as NMe2 possess more electron-donating ability than the S-based moieties such as SMe. Moreover, it was found that NMe2 showed higher luminescence quantum yields (ΦF) in comparison to SMe, indicating that N-substituted groups could enhance the fluorescence intensity. Therefore, the π-donor nature of the substituents on the phenyl ring constitutes the main parameter that influences the photophysical properties, such as excited state lifetimes and photoluminescence quantum yields. Hence, a series of highly luminescent materials from deep blue to red emission depending on substitution and environment is reported with potential applications in sensing, bioimaging and optoelectronics.

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