Intersystem crossing and internal conversion from the lowest charge-transfer singlet excited state of the (2,9-dimethyl-1,10-phenanthroline)copper(I) cation

1972 ◽  
pp. 1135 ◽  
Author(s):  
E. L. Wehry ◽  
S. Sundararajan
Keyword(s):  
Excited State ◽  
Charge Transfer ◽  
Internal Conversion ◽  
Intersystem Crossing ◽  
Singlet Excited State

scholarly journals Ultrafast intersystem crossing in xanthone from wavepacket dynamics

2021 ◽  
Author(s):  
Marc Alías Rodríguez ◽  
Coen De Graaf ◽  
Miquel Huix-Rotllant
Keyword(s):  
Excited State ◽  
Gas Phase ◽  
Internal Conversion ◽  
Singlet State ◽  
Minimum Energy ◽  
Intersystem Crossing ◽  
Singlet Excited State ◽  
Polar Solvents ◽  
Aromatic Ketones ◽  
Wavepacket Dynamics

Most aromatic ketones containing first-row elements undergo unexpectedly fast intersystem crossing in few tens of picoseconds and a quantum yield close to unity. Among them, xanthone (9H-xanthen-9-one) possesses one of the fastest singlet-triplet rates of ~1.5 ps. The exact mechanism of this unusually fast transition is still under debate. Here, we perform the wavepacket dynamics of the photochemistry of xanthone in the gas phase and in polar solvents. We show that xanthone follows El-Sayed's rule for intersystem crossing. From the second singlet excited state, the mechanism is sequential: (i) an internal conversion between singlets 1pipi*-1npi* (85 fs), (ii) an intersystem crossing 1npi*-3pipi* (2.0 ps), and (iii) an internal conversion between triplets 3pipi*-3npi* (602 fs). Each transfer finds its origin in a barrierless access to electronic state intersections. These intersections are close to minimum energy structures, allowing for efficient transitions from the initial singlet state to the triplets.

scholarly journals Excited State Dynamics of Cold Protonated Cytosine Tautomers: Characterization of Charge Transfer, Intersystem Crossing, and Internal Conversion Processes

2017 ◽  
Vol 121 (34) ◽  
pp. 6429-6439 ◽  
Author(s):  
Michel Broquier ◽  
Satchin Soorkia ◽  
Gustavo Pino ◽  
Claude Dedonder-Lardeux ◽  
Christophe Jouvet ◽  
...  
Keyword(s):  
Excited State ◽  
Charge Transfer ◽  
Internal Conversion ◽  
Intersystem Crossing ◽  
Excited State Dynamics ◽  
Protonated Cytosine

The photocycloaddition of dibenzoylmethanatoboron difluoride (DBMBF2) with conjugated enones and en-esters

1993 ◽  
Vol 71 (6) ◽  
pp. 846-854 ◽  
Author(s):  
Yuan L. Chow ◽  
Shi-Sen Wang ◽  
Xian-En Cheng
Keyword(s):  
Excited State ◽  
Charge Transfer ◽  
Ring Opening ◽  
Electron Donors ◽  
Head Orientation ◽  
Singlet Excited State ◽  
Methyl Substitution ◽  
Unsaturated Ketones ◽  
Dibenzoylmethanatoboron Difluoride

Dibenzoylmethanatoboron difluoride (DBMBF2), the BF2 complex of dibenzoylmethane, reacted from its singlet excited state with α,β-unsaturated ketones and esters to give 1,5-diketones by a [2+2] cycloaddition and ring-opening sequence in an analogous pathway to that observed in the photocycloaddition to olefins and dienes. The present photoreaction is unexpected since conjugated enones and en-esters are poor electron donors to comply with the previously proposed charge transfer requirement in DBMBF2 photoreactions. The photocycloaddition to these substrates was highly regioselective and stereoselective, giving the head-to-head orientation, which could be enhanced by α-methyl substitution; β-methyl substitution increased the alternate head-to-tail orientation. The photolysis of a mixture of DBMBF2 and a cyclic enone also caused the latter to dimerize to give head-to-head and head-to-tail dimers in significant yields. These photodimerizations were apparently caused by DBMBF2 sensitization. The mechanism of the sensitization is discussed.

Picosecond excited-state dynamics in octahedral cobalt(III) complexes: intersystem crossing versus internal conversion

1993 ◽  
Vol 32 (4) ◽  
pp. 394-399 ◽  
Author(s):  
James K. McCusker ◽  
Kevin N. Walda ◽  
Douglas Magde ◽  
David N. Hendrickson
Keyword(s):  
Excited State ◽  
Internal Conversion ◽  
Intersystem Crossing ◽  
Excited State Dynamics

scholarly journals Photoinduced Valence Tautomerism of a Cobalt-Dioxolene Complex Revealed with Femtosecond M-Edge XANES

2019 ◽  
Author(s):  
Ryan Ash ◽  
Kaili Zhang ◽  
Josh Vura-Weis
Keyword(s):  
Excited State ◽  
Charge Transfer ◽  
High Spin ◽  
Ground State ◽  
Extreme Ultraviolet ◽  
High Harmonic ◽  
Ligand Field ◽  
Intersystem Crossing ◽  
Valence Tautomerism ◽  
Reduced Forms

Cobalt complexes that undergo charge-transfer induced spin-transitions (CTIST) or valence tautomerism (VT) from low spin (LS) Co(III) to high spin (HS) Co(II) are potential candidates for magneto-optical switches. We use M-edge XANES spectroscopy with 40 fs time resolution to measure the excited-state dynamics of Co(III)(Cat-N-SQ)(Cat-N-BQ), where Cat-N-BQ and Cat-N-SQ are the singly and doubly reduced forms of the 2-(2-hydroxy-3,5-di-tert-butylphenyl-imino)-4,6-di-tert-butylcyclohexa-3,5-dienone ligand. The extreme ultraviolet probe pulses, produced using a tabletop high-harmonic generation light source, measure 3p3d transitions and are sensitive to the spin and oxidation state of the Co center. Photoexcitation at 525 nm produces a low-spin Co(II) ligand-to-metal charge transfer state which undergoes intersystem crossing to high-spin Co(II) in 67 fs. Vibrational cooling from this hot HS Co(II) state competes on the hundreds-of-fs timescale with back-intersystem crossing to the ground state, with 60% of the population trapped in a cold HS Co(II) state for 24 ps. Ligand field multiplet simulations accurately reproduce the ground-state spectra and support the excited-state assignments. This work demonstrates the ability of M-edge XANES to measure ultrafast photophysics of molecular Co complexes.<br><br><br>

Electron spin dynamics in excited state photochemistry: recent development in the study of the intersystem crossing and charge transfer in organic compounds

2021 ◽  
Author(s):  
MUHAMMAD IMRAN ◽  
Xue Zhang ◽  
Zhijia Wang ◽  
Xi Chen ◽  
Jianzhang Zhao ◽  
...  
Keyword(s):  
Excited State ◽  
Charge Transfer ◽  
Organic Compounds ◽  
Electron Spin ◽  
Spin Dynamics ◽  
Intersystem Crossing ◽  
Photophysical Processes ◽  
Electron Spin Dynamics

Electron spin dynamics are crucial to photochemical and photophysical processes. However, to large extent it is neglected in routine photochemistry studies. Herein we summarized the recent development of the electron...

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