Vibrational Analysis of the Radical Anion and Cation of Biphenyl Based on Density Functional Calculations

1996 ◽  
Vol 25 (10) ◽  
pp. 913-914 ◽  
Author(s):  
Kazuhiko Furuya ◽  
Hajime Torii ◽  
Yukio Furukawa ◽  
Mitsuo Tasumi
Keyword(s):  
Density Functional Calculations ◽  
Radical Anion ◽  
Density Functional ◽  
Vibrational Analysis

Vibrational spectra and electron–vibration interactions of the naphthalene radical anion — Experimental and theoretical study

2004 ◽  
Vol 82 (6) ◽  
pp. 951-963 ◽  
Author(s):  
Hajime Torii ◽  
Yuko Ueno ◽  
Akira Sakamoto ◽  
Mitsuo Tasumi
Keyword(s):  
Vibrational Spectra ◽  
Radical Anion ◽  
Density Functional ◽  
Vibrational Analysis ◽  
Radical Cations ◽  
Radical Anions ◽  
Molecular Symmetry ◽  
Complete Active Space ◽  
Symmetry Coordinates ◽  
Ir Intensities

Vibrational analysis is carried out for the radical anions of naphthalene-h8 and -d8. Their infrared (IR) spectra are observed in tetrahydrofuran by using a cell designed for IR measurements of unstable species. The vibrational force field and the IR intensities are calculated by the ab initio molecular orbital and density functional methods at various theoretical levels. As found in the cases of the radical cations of many polycyclic aromatic hydrocarbons (PAHs), a few strong IR bands with intensities of the order of 102 km mol–1 are observed in the 1700–900 cm–1 region. These observed spectral features are well reproduced by the calculations at the CASSCF (complete active space self-consistent field) and B3LYP (Becke's three-parameter hybrid method using the Lee–Yang–Parr correlation functional) levels. The calculation at the B3LYP level gives a better fit between the observed and calculated absolute IR intensities. Normal modes and the origin of the strong IR intensities characteristic of the radical anions are discussed in terms of molecular symmetry coordinates and the dipole derivatives based on these coordinates. It is found that the IR intensities of the b2u modes below 2000 cm–1 are dominated by the contribution from one molecular symmetry coordinate, in which the C—C bonds in one ring stretch while those in the other ring shrink. The mechanism that gives rise to the strong IR intensity for this vibration is discussed by examining the changes in the electronic structure induced by this vibration.Key words: vibrational spectra, electron–vibration interaction, naphthalene, radical anion.

Density Functional Calculations of EPR Parameter g Tensors of Some Transition Metal Complexes

2011 ◽  
Vol 2 (2) ◽  
pp. 139-141
Author(s):  
Vinita Prajapati ◽  
◽  
P.L.Verma P.L.Verma ◽  
Dhirendra Prajapati ◽  
B.K.Gupta B.K.Gupta
Keyword(s):  
Transition Metal ◽  
Metal Complexes ◽  
Transition Metal Complexes ◽  
Density Functional Calculations ◽  
Density Functional

scholarly journals Ultrafast proton release reaction and primary photochemistry of phycocyanobilin in solution observed with fs-time-resolved mid-IR and UV/Vis spectroscopy

2021 ◽  
Author(s):  
Maximilian Theiß ◽  
Merten Grupe ◽  
Tilman Lamparter ◽  
Maria Andrea Mroginski ◽  
Rolf Diller
Keyword(s):  
Density Functional ◽  
Transient Absorption ◽  
Vibrational Analysis ◽  
Density Functional Theory Calculations ◽  
Chem Phys ◽  
Molecular Structures ◽  
Ir Absorption ◽  
Time Resolved ◽  
Time Constants ◽  
Vis Spectroscopy

AbstractDeactivation processes of photoexcited (λex = 580 nm) phycocyanobilin (PCB) in methanol were investigated by means of UV/Vis and mid-IR femtosecond (fs) transient absorption (TA) as well as static fluorescence spectroscopy, supported by density-functional-theory calculations of three relevant ground state conformers, PCBA, PCBB and PCBC, their relative electronic state energies and normal mode vibrational analysis. UV/Vis fs-TA reveals time constants of 2.0, 18 and 67 ps, describing decay of PCBB*, of PCBA* and thermal re-equilibration of PCBA, PCBB and PCBC, respectively, in line with the model by Dietzek et al. (Chem Phys Lett 515:163, 2011) and predecessors. Significant substantiation and extension of this model is achieved first via mid-IR fs-TA, i.e. identification of molecular structures and their dynamics, with time constants of 2.6, 21 and 40 ps, respectively. Second, transient IR continuum absorption (CA) is observed in the region above 1755 cm−1 (CA1) and between 1550 and 1450 cm−1 (CA2), indicative for the IR absorption of highly polarizable protons in hydrogen bonding networks (X–H…Y). This allows to characterize chromophore protonation/deprotonation processes, associated with the electronic and structural dynamics, on a molecular level. The PCB photocycle is suggested to be closed via a long living (> 1 ns), PCBC-like (i.e. deprotonated), fluorescent species.

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