Electron transfer from ground-state triethylamine to the second and lowest excited triplet states of haloanthraquinones (1-chloro, 2-chloro, 1,5-dichloro, 1,8-dichloro, and 1,8-dibromo compounds) in acetonitrile at room temperature studied by picosecond and nanosecond laser spectroscopy

1992 ◽  
Vol 96 (9) ◽  
pp. 3736-3741 ◽  
Author(s):  
Kumao Hamanoue ◽  
Toshihiro Nakayama ◽  
Satoshi Asada ◽  
Kazuyasu Ibuki
Keyword(s):  
Electron Transfer ◽  
Laser Spectroscopy ◽  
Ground State ◽  
Room Temperature ◽  
Nanosecond Laser ◽  
Triplet States ◽  
Excited Triplet ◽  
Excited Triplet States

Protonation of some non-transition metal phthalocyanines — spectral and photophysicochemical consequences

2012 ◽  
Vol 16 (07n08) ◽  
pp. 885-894 ◽  
Author(s):  
Abimbola O. Ogunsipe ◽  
Mopelola A. Idowu ◽  
Taofeek B. Ogunbayo ◽  
Isaac A. Akinbulu
Keyword(s):  
Transition Metal ◽  
Rate Constant ◽  
Rate Equation ◽  
Aluminum Chloride ◽  
Ground State ◽  
Triplet States ◽  
Metal Phthalocyanines ◽  
Excited Triplet ◽  
Kinetics Of ◽  
Excited Triplet States

The photophysics and photochemistry of phthalocyanine complexes of magnesium (MgPc), aluminum chloride (ClAlPc) and zinc (ZnPc) are studied in N,N′-dimethylformamide (DMF). The values obtained for the photophysical and photochemical parameters are normal for simple metallophthalocyanine (MPc) complexes. Protonation of the azomethine bridges reduced the photoactivities of the complexes considerably; however the excited triplet states of the protonated species are more stable towards ground state oxygen. The interaction of the non-protonated MPcs with ground state oxygen is shown to be diffusion-assisted, with bimolecular rate constant values of the order of 1010 M-1.s-1. MgPc could not be protonated; it was easily demetalated by the protonating acid. The kinetics of the demetalation yielded the rate equation: Rate = 0.1[MgPc][H+]2/3

Monitoring the Formation and Decay of Transient Photosensitized Intermediates Using Pump-Probe UV Resonance Raman Spectroscopy. I: Self-Modeling Curve Resolution

2003 ◽  
Vol 57 (4) ◽  
pp. 439-447 ◽  
Author(s):  
James A. Kleimeyer ◽  
Joel M. Harris
Keyword(s):  
Factor Analysis ◽  
Excited State ◽  
Ground State ◽  
Pure Component ◽  
Triplet States ◽  
Time Resolved ◽  
Pump Probe ◽  
Excited Triplet ◽  
Curve Resolution ◽  
Excited Triplet States

Resolution of transient excited-state Raman scattering from ground-state and solvent bands is a challenging spectroscopic measurement since excited-state spectral features are often of low intensity, overlapping the dominant ground-state and solvent bands. The Raman spectra of these intermediates can be resolved, however, by acquiring time-resolved data and using multidimensional data analysis methods. In the absence of a physical model describing the kinetic behavior of a reaction, resolution of the pure-component spectra from these data can be accomplished using self-modeling curve resolution, a factor analysis technique that relies on the correlation in the data along a changing composition dimension to resolve the component spectra. A two-laser UV pump-probe resonance-enhanced Raman instrument was utilized to monitor the kinetics of amine quenching of excited-triplet states of benzophenone. The formation and decay of transient intermediates were monitored over time, from 15 ns to 100 μs. Factor analysis of the time-resolved spectral data identified three significant components in the data. The time-resolved intensities at each Raman wavenumber shift were projected onto the three significant eigenvectors, and least-squares criteria were developed to find the common plane in the space of the eigenvectors that includes the observed data. Within that plane, the three pure-component spectra were resolved using geometric criteria of convex hull analysis. The resolved spectra were found to arise from benzophenone excited-triplet states, diphenylketyl radicals, and the solvent and ground-state benzophenone.

Geometries of the ground and first excited triplet states of thioformaldehyde

1981 ◽  
Vol 59 (22) ◽  
pp. 3200-3203 ◽  
Author(s):  
John D. Goddard
Keyword(s):  
Ground State ◽  
Reasonable Agreement ◽  
Basis Sets ◽  
Triplet States ◽  
Gaussian Basis Sets ◽  
Excited Triplet ◽  
Polarization Functions ◽  
Scf Calculations ◽  
Split Valence ◽  
Excited Triplet States

The geometries of the S0 and T1 states of thioformaldehyde are determined by ab initio SCF calculations with Gaussian basis sets ranging from minimal to double ζ plus both diffuse and polarization functions. The ground state geometries are all in reasonable agreement with experiment but for the n → π* triplet state split valence or double ζ basis sets yield unreasonably long CS bond distances.

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