Photochemical synthesis and photophysical features of ethynylphenanthrenes studied by emission and transient absorption measurements

2016 ◽  
Vol 15 (12) ◽  
pp. 1586-1593 ◽  
Author(s):  
Yuma Hakoda ◽  
Masatoshi Aoyagi ◽  
Ken-ichi Irisawa ◽  
Shin-ichiro Kato ◽  
Yosuke Nakamura ◽  
...  
Keyword(s):  
Transient Absorption ◽  
Photochemical Synthesis ◽  
Triple Bonds ◽  
Absorption Measurements

Phenanthrenes substituted with C–C triple bonds were photochemically prepared, and the photophysical features in solution were investigated based on emission and transient absorption measurements.

scholarly journals Substitution Effects of C-C Triple Bonds on Deactivation Processes from the Fluorescent State of Pyrene Studied by Emission and Transient Absorption Measurements

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
Minoru Yamaji ◽  
Hajime Maeda ◽  
Yasuaki Nanai ◽  
Kazuhiko Mizuno
Keyword(s):  
Triple Bond ◽  
Transient Absorption ◽  
Heavy Atom ◽  
Substitution Effects ◽  
Triple Bonds ◽  
Pyrene Derivatives ◽  
Fluorescent State ◽  
Atom Effect ◽  
Absorption Measurements ◽  
Triplet Absorption

Pyrenes substituted with tert-butylethynyl, trimethylsilylethynyl, and trimethylsilylbutadiynyl groups were prepared, and the fluorescence yields (Φf), lifetimes, and triplet-triplet absorption were measured in cyclohexane. Upon introduction of the groups possessing triple bond(s) to the pyrene skeleton, the fluorescence rate (kf) increased. The variation of the terminating groups did not appreciably affect the Φf and kf values. Increasing the number of the triple bond, the kf values increased by the magnitude of order whereas the Φf were not varied. The effect of the ethynyl groups on the kf values was rationalized by the Strickler-Berg equation considering an increase of the 1La transition moment. Triplet-triplet absorption spectra of pyrene derivatives were obtained. The intersystem crossing rates (kisc) increased upon increasing the number of triple bonds terminated with the trimethylsilyl group whereas those between ethynylpyrenes were independent of the terminating groups. Heavy atom effect failed to rationalize the enhancement of the kisc values upon adding the triple bond to the pyrene moiety.

Photochemical synthesis and photophysical properties of coumarins bearing extended polyaromatic rings studied by emission and transient absorption measurements

2017 ◽  
Vol 16 (4) ◽  
pp. 555-563 ◽  
Author(s):  
Minoru Yamaji ◽  
Yuma Hakoda ◽  
Hideki Okamoto ◽  
Fumito Tani
Keyword(s):  
Transient Absorption ◽  
Photophysical Properties ◽  
Photochemical Synthesis ◽  
Electron Systems ◽  
Absorption Measurements

Coumarins having expanded π-electron systems were prepared via a photocondensation process and the photophysical features in solution were investigated based on emission and transient absorption measurements.

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 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

Determination of Atomic Velocity Distributions Using Transient Absorption Measurements

1992 ◽  
Vol 285 ◽  
Author(s):  
Michel Macler ◽  
Mario E. Fajardo
Keyword(s):  
Transient Absorption ◽  
Emission Spectra ◽  
Leading Edge ◽  
Target Surface ◽  
Spatial Separation ◽  
Laser Pulses ◽  
Stream Velocity ◽  
Ablation Laser ◽  
Atomic Beams ◽  
Absorption Measurements

ABSTRACTResults of experiments on Al, Li, and Na atomic beams produced by laser ablation using XeCI excimer laser pulses (I∼107 to l08 W/cm2) are presented. Plume emission spectra showed that further than ∼5 mm from the targets most of the excited ablated species are in neutral, atomic form. Transient absorption measurements permitted the detection of ground state atoms with different flight times, at fixed distances from the target. The resulting time of flight (TOF) distributions were converted into velocity and kinetic energy (KE) distributions.The measured fluxes of fast atoms always increased with ablation laser intensity. The velocity distributions could not be fitted to Maxwell-Boltzmann (MB), or MB plus stream velocity type distributions. For Al plumes, comparison of velocity distributions measured at various distances from the target surface indicates that Al atoms are produced within ∼100 nsec following the leading edge of the ablation laser pulse, implying that there is a one-to-one mapping of the initial velocities to the distances traveled by the atoms after ∼1 μsec. This result should encourage efforts to develop a method of velocity selection of laser ablated metal atoms based on the spatial separation of the various velocity components along the direction of travel.

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