Computer-assisted resolution of transient absorption bands of phenyldibenzophosphole in fluid solution. Further evidence for triplet excimers

1994 ◽  
Vol 226 (5-6) ◽  
pp. 552-558 ◽  
Author(s):  
Tapan Ganguly ◽  
R.D. Burkhart
Keyword(s):  
Transient Absorption ◽  
Computer Assisted ◽  
Fluid Solution ◽  
Absorption Bands

Efficient photoinduced electron transfer between C60/C70 and zinc octaethylporphyrin studied by nanosecond laser photolysis method

2000 ◽  
Vol 04 (06) ◽  
pp. 591-598 ◽  
Author(s):  
MOHAMED E. EL-KHOULY ◽  
MAMORU FUJITSUKA ◽  
OSAMU ITO
Keyword(s):  
Electron Transfer ◽  
Rate Constants ◽  
Photoinduced Electron Transfer ◽  
Transfer Rate ◽  
Transient Absorption ◽  
Laser Light ◽  
Solvent Polarity ◽  
Nanosecond Laser ◽  
Electron Transfer Rate ◽  
Absorption Bands

Photoinduced electron-transfer processes between C 60 or C 70 and zinc octaethylporphyrin ( ZnOEP ) have been studied in polar solvents with the nanosecond laser flash photolysis method, observing the transient absorption spectra in the visible and near-IR regions. By the predominant excitation of ZnOEP with 532 nm laser light the transient absorption bands of 3 ZnOEP * decayed, accompanied by the appearance of the transient absorption bands of [Formula: see text] and [Formula: see text]. By the predominant excitation of C 60 and C 70 with 610 nm laser light the decays of [Formula: see text] and [Formula: see text] were observed, accompanied by the appearance of [Formula: see text] and [Formula: see text]. The electron transfer rate constants (k et ) and the quantum yields (Φ et ) of [Formula: see text] and [Formula: see text] formation via 3 ZnOEP * and [Formula: see text] or [Formula: see text] have been evaluated. These values increase with the solvent polarity; in polar benzonitrile these values are higher than for other porphyrins such as zinc tetraphenylporphyrin. The back electron transfer rate constants were evaluated from the decays of [Formula: see text] and [Formula: see text], which also show a solvent polarity dependence.

WAVE PACKET MOTIONS COUPLED TO ELECTRON TRANSFER IN REACTION CENTERS OF CHLOROFLEXUS AURANTIACUS

2008 ◽  
Vol 06 (04) ◽  
pp. 643-666 ◽  
Author(s):  
ANDREI G. YAKOVLEV ◽  
TATIANA A. SHKUROPATOVA ◽  
LYUDMILA G. VASILIEVA ◽  
ANATOLI YA. SHKUROPATOV ◽  
VLADIMIR A. SHUVALOV
Keyword(s):  
Electron Transfer ◽  
Absorption Band ◽  
Wave Packet ◽  
Transient Absorption ◽  
Primary Electron ◽  
Reaction Centers ◽  
Stimulated Emission ◽  
Spectral Evolution ◽  
Absorption Bands ◽  
Absorbance Changes

Transient absorption difference spectroscopy with ~20 femtosecond (fs) resolution was applied to study the time and spectral evolution of low-temperature (90 K) absorbance changes in isolated reaction centers (RCs) of Chloroflexus (C.) aurantiacus. In RCs, the composition of the B-branch chromophores is different with respect to that of purple bacterial RCs by occupying the BB binding site of accessory bacteriochlorophyll by bacteriopheophytin molecule (ΦB). It was found that the nuclear wave packet motion induced on the potential energy surface of the excited state of the primary electron donor P* by ~20 fs excitation leads to a coherent formation of the states [Formula: see text] and [Formula: see text] (BA is a bacteriochlorophyll monomer in the A-branch of cofactors). The processes were studied by measuring coherent oscillations in kinetics of the absorbance changes at 900 nm and 940 nm (P* stimulated emission), at 750 nm and 785 nm (ΦB absorption bands), and at 1,020–1028 nm ([Formula: see text] absorption band). In RCs, the immediate bleaching of the P band at 880 nm and the appearance of the stimulated wave packet emission at 900 nm were accompanied (with a small delay of 10–20 fs) by electron transfer from P* to the B-branch with bleaching of the ΦB absorption band at 785 nm due to [Formula: see text] formation. These data are consistent with recent measurements for the mutant HM182L Rb. sphaeroides RCs (Yakovlev et al., Biochim Biophys Acta1757:369–379, 2006). Only at a delay of 120 fs was the electron transfer from P* to the A-branch observed with a development of the [Formula: see text] absorption band at 1028 nm. This development was in phase with the appearance of the P* stimulated emission at 940 nm. The data on the A-branch electron transfer in C. aurantiacus RCs are consistent with those observed in native RCs of Rb. sphaeroides. The mechanism of charge separation in RCs with the modified B-branch pigment composition is discussed in terms of coupling between the nuclear wave packet motion and electron transfer from P* to ΦB and BA primary acceptors in the B-branch and A-branch, respectively.

Spectroscopic signatures of ligand field states in {RuII(imine)} complexes

2016 ◽  
Vol 45 (13) ◽  
pp. 5464-5475 ◽  
Author(s):  
Alejandro Cadranel ◽  
German E. Pieslinger ◽  
Pornthip Tongying ◽  
Masaru K. Kuno ◽  
Luis M. Baraldo ◽  
...  
Keyword(s):  
Dft Calculations ◽  
Transient Absorption ◽  
Ligand Field ◽  
Absorption Bands ◽  
Td Dft ◽  
Spectroscopic Signatures ◽  
Decay Cascade

Clear spectroscopic signatures of ligand field states in the MLCT decay cascade of trans-[Ru(L)4(NCS)2] (L = pyridine or 4-methoxypyridine) were found. (TD)DFT calculations reveal the presence of both MLCT and LMCT transient absorption bands.

Photoinduced electron transfer from triplet states of phthalocyanines to fullerenes studied by transient absorption spectroscopies in visible and near-IR regions

2000 ◽  
Vol 04 (08) ◽  
pp. 713-721 ◽  
Author(s):  
MOHAMED E. EL-KHOULY ◽  
SHAFIQUL D.-M. ISLAM ◽  
MAMORU FUJITSUKA ◽  
OSAMU ITO
Keyword(s):  
Electron Transfer ◽  
Photoinduced Electron Transfer ◽  
Transient Absorption ◽  
Triplet States ◽  
Absorption Bands ◽  
Polar Solvents ◽  
Transfer Processes ◽  
Near Ir ◽  
Electron Transfer Processes ◽  
Electron Ejection

Photoinduced electron transfer processes between C 60/ C 70 and phthalocyanines such as tetra-tert-butylphthalocyanine ( H 2 TBPc ) and its zinc derivative ( ZnTBPc ) in polar solvents have been studied by observing the transient absorption spectra in the visible and near-IR regions. Upon predominant excitation of TBPcs with a 670 nm laser pulse in polar solvents, growth of the transient absorption bands of [Formula: see text] and [Formula: see text] was observed, accompanied by a concurrent decay of the triplet states of TBPcs (3 TBPc *). Thus it is confirmed that electron transfer occurs via 3 TBPc * in polar solvents. The electron transfer rate constants and efficiencies of electron transfer via 3 ZnTBPc * are greater than those via 3 H 2 TBPc * owing to the electron ejection ability of 3 ZnTBPc *. Solvent effects on the forward and backward electron transfer processes have been evaluated.

S2→S1 Internal Conversion in β-Carotene: Strong Vibronic Coupling from Amplitude Oscillations of Transient Absorption Bands

2007 ◽  
Vol 46 (20) ◽  
pp. 3758-3761 ◽  
Author(s):  
J. Luis Pérez Lustres ◽  
Alexander L. Dobryakov ◽  
Alfred Holzwarth ◽  
Manoel Veiga
Keyword(s):  
Internal Conversion ◽  
Transient Absorption ◽  
Vibronic Coupling ◽  
Absorption Bands ◽  
Β Carotene

Photoinduced electron-transfer processes between phthalocyanines and perylene derivatives

2006 ◽  
Vol 10 (10) ◽  
pp. 1190-1196 ◽  
Author(s):  
Koji Kitazume ◽  
Yu Chen ◽  
Mitsunari Itou ◽  
Yasuyuki Araki ◽  
Satoshi Uchida ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Photoinduced Electron Transfer ◽  
Transient Absorption ◽  
Triplet States ◽  
Intermolecular Electron Transfer ◽  
Absorption Bands ◽  
Time Resolved ◽  
Transfer Processes ◽  
Perylene Derivatives ◽  
Electron Transfer Processes

Photoinduced electron-transfer processes between phthalocyanines ( H2Pc and ZnPc ) as electron donors and perylene derivatives as electron acceptors have been studied using a time-resolved, nanosecond transient absorption method in benzonitrile. The observed findings show that intermolecular electron transfer takes place via the excited triplet states of ZnPc and H2Pc , as confirmed by the characteristic transient absorption bands in the near-IR region. The visible light excitation of the mixtures of H2Pc and the perylene derivatives adsorbed onto TiO2gave a relatively high photovoltaic efficiency.

Light harvesting phthalocyanine/subphthalocyanine system: intermolecular electron-transfer and energy-transfer reactions via the triplet subphthalocyanine

2011 ◽  
Vol 15 (02) ◽  
pp. 111-117 ◽  
Author(s):  
Mohamed E. El-Khouly ◽  
Shunichi Fukuzumi
Keyword(s):  
Electron Transfer ◽  
Energy Transfer ◽  
Excited State ◽  
Transfer Process ◽  
Radical Anion ◽  
Transient Absorption ◽  
Nanosecond Laser ◽  
Triplet Excited State ◽  
Intermolecular Electron Transfer ◽  
Absorption Bands

Photoinduced electron transfer from the electron-donating zinc tetra-tert-butylphthalocyanine, ZnTBPc , to the electron-accepting dodecafluorosubphthalocyanine, SubPcF12 , in the polar benzonitrile has been investigated with nanosecond laser photolysis method. The examined ZnTBPc/SubPcF12 mixture absorbs the light in a wide section of the UV/vis/NIR spectra. Owing to the particular electronic properties of both entities, such combination seems to be perfectly suited for the study of intermolecular electron-transfer process in the polar solvents via the triplet-excited state of SubPcF12 . Upon excitation of SubPcF12 with 570 nm laser light in polar benzonitrile (εs = 25.2), the electron transfer from ZnTBPc to the triplet-excited state of SubPcF12 was confirmed by observing the transient absorption bands of ZnTBPc radical cation and SubPcF12 radical anion in the visible and near-IR region. On addition of an appropriate electron acceptor with excellent electron-accepting properties, namely dicyanoperylene-3,4,9,10-bis(dicarboximide) ( PDICN2 ), the anion radical of SubPcF12 transfers to the PDICN2 yielding the PDICN2 radical anion. These observations confirm the photosensitized electron-transfer/electron-mediating cycle of ZnTBPc/SubPcF12/PDICN2 system. In non-polar toluene (εs = 2.2), the energy-transfer process from the triplet-excited state of SubPcF12 to the low-lying triplet state of ZnTBPc was confirmed by the consecutive appearance of the triplet ZnTBPc .

Luminescence and transient absorption bands in fused SiO2 induced by KrF laser radiation at various temperatures

1992 ◽  
Vol 149 (1-2) ◽  
pp. 115-121 ◽  
Author(s):  
N. Leclerc ◽  
C. Pfleiderer ◽  
H. Hitzler ◽  
J. Wolfrum ◽  
K.-O. Greulich ◽  
...  
Keyword(s):  
Laser Radiation ◽  
Transient Absorption ◽  
Absorption Bands ◽  
Krf Laser

Polarimetric Observations of Red Variables: A Study of Gas and Particle Interactions

1979 ◽  
Vol 46 ◽  
pp. 386-408 ◽  
Author(s):  
G. V. Coyne ◽  
I. S. McLean
Keyword(s):  
Wavelength Dependence ◽  
Stellar Atmosphere ◽  
Molecular Absorption ◽  
Absorption Bands ◽  
Absorption And Emission ◽  
Mira Variables ◽  
Stellar Photosphere ◽  
Regular Variable ◽  
Red Supergiants ◽  
Balmer Lines

AbstractIn recent years the wavelength, dependence of the polarization in a number of Mira variables, semi-regular variables and red supergiants has been measured with resolutions between 0.3 and 300 A over the range 3300 to 11000 A. Variations are seen across molecular absorption bands, especially TiO bands, and across atomic absorption and emission lines, especially the Balmer lines. In most cases one can ignore or it is possible to eliminate the effects due to interstellar polarization, so that one can study the polarization mechanisms operating in the stellar atmosphere and environment. The stars Omicron Ceti. (Mira), V CVn (semi-regular variable) and Mu Cephei (M2 la), in addition to other stars similar to them, will be discussed in some detail.Models to explain the observed polarization consider that the continuum flux is polarized either by electron, molecular and/or grain scattering or by temperature variations and/or geometrical asymmetries over the stellar photosphere. This polarized radiation is affected by atomic and molecular absorption and emission processes at various geometric depths in the stellar atmosphere and envelope. High resolution spectropolarimetry promises, therefore, to be a power-rul tool for studying stratification effects in these stars.

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