Solvent-induced multicolour fluorescence of amino-substituted 2,3-naphthalimides studied by fluorescence and transient absorption measurements

2016 ◽  
Vol 15 (7) ◽  
pp. 842-850 ◽  
Author(s):  
Mayu Fujii ◽  
Misa Namba ◽  
Minoru Yamaji ◽  
Hideki Okamoto
Keyword(s):  
Internal Conversion ◽  
Transient Absorption ◽  
Fluorescence Emission ◽  
Conversion Process ◽  
Absorption Measurements

Amino-substituted 2,3-naphthalimide derivatives showed marked positive solvatofluorochromism, and the fluorescence emission was effectively quenched in methanol via the internal conversion process.

scholarly journals Direct Observation of S2–S1 Internal Conversion in Pyrene by Femtosecond Transient Absorption

1999 ◽  
Vol 19 (1-4) ◽  
pp. 375-379 ◽  
Author(s):  
Frederik V. R. Neuwahl ◽  
Paolo Foggi
Keyword(s):  
Time Constant ◽  
Absorption Spectroscopy ◽  
Direct Observation ◽  
Internal Conversion ◽  
Transient Absorption ◽  
Conversion Process ◽  
Transient Absorption Spectroscopy ◽  
Kinetic Measurements ◽  
State Population ◽  
Femtosecond Transient Absorption

UV pulses of 100 fs at 340 nm are utilised to excite pyrene to the vibrationally cold S2 state. Population and depopulation processes occurring in the S2 state are investigated by transient absorption spectroscopy with a white continuum probe. In the first 400 fs after excitation it is possible to measure the growth and disappearance of a band at 585 nm which is assigned to the S14←S2 transition. As a consequence of the internal conversion process from S2 to S1 state, the disappearance of the 585 nm band and the growth of the transient spectrum due to Sn←S1 transitions can be observed. Kinetic measurements of the S2 decay and S1 growing signals provide an estimate of the rate of internal conversion which occurs with a time constant of 150±50 fs.

K shell X-ray intensity ratios, K-Li, K-L, and K-M vacancy transfer probabilities of Ba and Tl following internal conversion process

2014 ◽  
Vol 92 (11) ◽  
pp. 1489-1493 ◽  
Author(s):  
P.V. Sreevidya ◽  
S.B. Gudennavar ◽  
Daisy Joseph ◽  
S.G. Bubbly
Keyword(s):  
Beta Decay ◽  
Internal Conversion ◽  
Experimental Results ◽  
Conversion Process ◽  
X Rays ◽  
X Ray ◽  
Multichannel Analyser ◽  
Intensity Ratios

K shell X-rays of barium and thallium following internal conversion decay in Cs137 and Hg203, respectively, were detected using a Si(Li) X-ray detector coupled to PC-based 8k multichannel analyser employing the method suggested earlier by our group. The K shell X-ray intensity ratios and vacancy transfer probabilities for thallium and barium were calculated. The obtained results are compared with theoretical, semiempirical, and others’ experimental results obtained via photoionization as well as decay processes. The effects of beta decay and internal conversion on X-ray emission probabilities are discussed.

The Efficiency of the Internal Conversion Process in Br80

1949 ◽  
Vol 17 (2) ◽  
pp. 215-215 ◽  
Author(s):  
William H. Hamill ◽  
J. A. Young
Keyword(s):  
Internal Conversion ◽  
Conversion Process

Contactless Spatially Resolved Measurement of Bulk Free-Carrier Lifetime in Silicon Ingots

1986 ◽  
Vol 69 ◽  
Author(s):  
S. M. Johnson ◽  
L. G. Johnson ◽  
R. Hemphill
Keyword(s):  
Spatial Dependence ◽  
Polycrystalline Silicon ◽  
Carrier Lifetime ◽  
Transient Absorption ◽  
Free Carrier ◽  
Large Area ◽  
Spatially Resolved ◽  
Probe Transmission ◽  
Transmission Measurements ◽  
Absorption Measurements

AbstractA contactless spatially resolved measurement of bulk free-carrier lifetime in polycrystalline silicon ingots was accomplished using optically modulated free-carrier infrared absorption. Using a CW Nd:YAG laser (λ = 1.319 μm) for a probe and novel pulsed, tunable, infrared dye laser (λ = 1.10 to 1.13 μm) with photon energies near the Si bandgap, for a pump, the free-carrier lifetime was determined from transient absorption measurements to a maximum depth of 3.0 cm from the surface of an ingot. The spatial dependence of the free-carrier lifetime and the distribution of precipitates (determined from infrared probe transmission measurements) measured along the growth axis of an ingot were found to be strongly related to the spatial dependence of the I–V characteristics of large area solar cells fabricated from the subsequently wafered ingot.

Unusually Strong Bi-Exciton Repulsion Detected in Quantum Confined CsPbBr3 Nanocrystals with Two and Three Pulse Femtosecond Spectroscopy

2021 ◽  
Author(s):  
jayanta dana ◽  
Tal Binyamin ◽  
Lioz Etgar ◽  
Sanford Ruhman
Keyword(s):  
Cross Section ◽  
Quantum Confinement ◽  
Auger Recombination ◽  
Transient Absorption ◽  
Stimulated Emission ◽  
Band Edge ◽  
High Time Resolution ◽  
Difference Spectra ◽  
The Difference ◽  
Absorption Measurements

Transient absorption measurements were conducted on pristine and on monoexciton saturated<br>CsPbBr3 nanocrystals varying in size within the regime of strong quantum confinement. Once<br>the difference spectra were translated to absolute transient changes in absorption cross section,<br>a single exciton is shown to completely bleach the band edge absorption peak, and induce a<br>new absorption roughly two times weaker ~100 meV to the blue. Difference spectra obtained<br>during Auger recombination of biexcitons demonstrate that addition of a second exciton, rather<br>than double the effect of a first, bleaches the blue induced absorption band without producing<br>net stimulated emission at the band edge. Accompanied by high time resolution transient<br>absorption spectra pumping at the lowest exciton band, these results identify the blue induced<br>absorption as the second transition to 1Se1Sh which is shifted in energy due to unusually strong<br>and promptly rising biexciton repulsion. <br>

scholarly journals A photosynthetic antenna complex foregoes unity carotenoid-to-bacteriochlorophyll energy transfer efficiency to ensure photoprotection

2020 ◽  
Vol 117 (12) ◽  
pp. 6502-6508 ◽  
Author(s):  
Dariusz M. Niedzwiedzki ◽  
David J. K. Swainsbury ◽  
Daniel P. Canniffe ◽  
C. Neil Hunter ◽  
Andrew Hitchcock
Keyword(s):  
Energy Transfer ◽  
Transient Absorption ◽  
Light Harvesting ◽  
Protein Complexes ◽  
Fluorescence Emission ◽  
Energy Transfer Efficiency ◽  
Transfer Efficiency ◽  
Light Harvesting Complexes ◽  
Antenna Complex ◽  
Pigment Protein Complexes

Carotenoids play a number of important roles in photosynthesis, primarily providing light-harvesting and photoprotective energy dissipation functions within pigment–protein complexes. The carbon–carbon double bond (C=C) conjugation length of carotenoids (N), generally between 9 and 15, determines the carotenoid-to-(bacterio)chlorophyll [(B)Chl] energy transfer efficiency. Here we purified and spectroscopically characterized light-harvesting complex 2 (LH2) fromRhodobacter sphaeroidescontaining theN= 7 carotenoid zeta (ζ)-carotene, not previously incorporated within a natural antenna complex. Transient absorption and time-resolved fluorescence show that, relative to the lifetime of the S1state of ζ-carotene in solvent, the lifetime decreases ∼250-fold when ζ-carotene is incorporated within LH2, due to transfer of excitation energy to the B800 and B850 BChlsa. These measurements show that energy transfer proceeds with an efficiency of ∼100%, primarily via the S1→ Qxroute because the S1→ S0fluorescence emission of ζ-carotene overlaps almost perfectly with the Qxabsorption band of the BChls. However, transient absorption measurements performed on microsecond timescales reveal that, unlike the nativeN≥ 9 carotenoids normally utilized in light-harvesting complexes, ζ-carotene does not quench excited triplet states of BChla, likely due to elevation of the ζ-carotene triplet energy state above that of BChla. These findings provide insights into the coevolution of photosynthetic pigments and pigment–protein complexes. We propose that theN≥ 9 carotenoids found in light-harvesting antenna complexes represent a vital compromise that retains an acceptable level of energy transfer from carotenoids to (B)Chls while allowing acquisition of a new, essential function, namely, photoprotective quenching of harmful (B)Chl triplets.

scholarly journals Exciton dynamics in DNA oligomers studied by broadband deep-UV transient absorption spectroscopy

2019 ◽  
Vol 205 ◽  
pp. 10006
Author(s):  
Benjamin Bauer ◽  
Malte Oppermann ◽  
Majed Chergui
Keyword(s):  
Absorption Spectroscopy ◽  
Transient Absorption ◽  
Transient Absorption Spectroscopy ◽  
Base Stacking ◽  
Dna Oligomers ◽  
Exciton Dynamics ◽  
Deep Uv ◽  
Strand Length ◽  
Absorption Measurements

We report broadband transient absorption measurements of adenine strands in the deep-UV (250-370 nm). By varying the strand length we resolve the interplay between inter-base stacking and exciton formation and dynamics in DNA oligomers.

Femtosecond transient absorption measurements in poly(arylenevinylene)s

1993 ◽  
Vol 55 (1) ◽  
pp. 15-21 ◽  
Author(s):  
I.D.W. Samuel ◽  
F. Raksi ◽  
D.D.C. Bradley ◽  
R.H. Friend ◽  
P.L. Burn ◽  
...  
Keyword(s):  
Transient Absorption ◽  
Femtosecond Transient Absorption ◽  
Absorption Measurements

Synthesis, characterization and photophysical properties of ferrocenyl and mixed sandwich cobaltocenyl ester linked meso-triaryl corrole dyads

2017 ◽  
Vol 21 (10) ◽  
pp. 646-657 ◽  
Author(s):  
B. Shivaprasad Achary ◽  
A. R. Ramya ◽  
Rajiv Trivedi ◽  
P. R. Bangal ◽  
L. Giribabu
Keyword(s):  
Transient Absorption ◽  
Photophysical Properties ◽  
Heavy Atom ◽  
Parent Compound ◽  
Fluorescence Emission ◽  
Soret Band ◽  
Transient Absorption Spectroscopy ◽  
Ferrocene Derivatives ◽  
Time Resolved ◽  
Design And Synthesis

We report here the design and synthesis of corrole-metallocene dyads consisting of a metallocene (either ferrocene (Dyad 1) or mixed sandwich [Formula: see text]-[C[Formula: see text]H[Formula: see text](COOH)]Co([Formula: see text]-C[Formula: see text]Ph[Formula: see text] (Dyad 2)) connected via an ester linkage at meso phenyl position. Both the dyads were characterized by [Formula: see text]H NMR, MALDI-TOF, UV-visible, fluorescence spectroscopies (steady-state, picosecond time-resolved), femtosecond transient absorption spectroscopy (fs-TA) and electrochemical methods. The absorption spectra of these dyads showed slight broadening and splitting of the Soret band that indicates a weak ground state interaction between the corrole macrocycle and metallocene part of the present donor–acceptor (D–A) system. However, in both the dyad systems, fluorescence emission of the corrole was quenched in polar solvents as compared to its parent compound 10-(4-hydroxyphenyl)-5,15-bis-(pentafluorophenyl ) corrole (Ph-Corr). The quenching was more pronounced in ferrocene derivatives than in cobaltocenyl derivatives. Transient absorption studies confirm the absence of photoinduced electron transfer from metallocene to correl for these dyad systems and the quenching of singlet state of corrole is found to enhance intersystem crossing due to heavy atom effect.

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