Untitled

Kuz'mitskii, V. A.

doi:10.1023/a:1013229530258

Cited by 7 publications

(7 citation statements)

References 16 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Further in the rest of this section, we consider these previously obtained results and compare them to our experiment. 33 On the other hand, an inclusion of a limited number of doubly excited configurations in CNDO CIS ͑Ref. For metallophthalocyanines, a number of configuration interaction ͑CI͒ calculations 30-34 reveal the first g-g transition lying somewhere between 16 070 and 22 900 cm −1 , which correlates well with our experimental result, g-g = 22 750 cm −1 .…”

Section: Two-photon Absorptionsupporting

confidence: 78%

Near-infrared two-photon absorption in phthalocyanines: Enhancement of lowest gerade-gerade transition by symmetrical electron-accepting substitution

Drobizhev

Makarov

Stepanenko

et al. 2006

The Journal of Chemical Physics

View full text Add to dashboard Cite

This paper presents, to the best of our knowledge, the first study of two-photon absorption (2PA) spectra of a number of symmetrically substituted phthalocyanines in the excitation wavelength region from lambda(ex)=800 to 1600 nm. The selected molecules vary by position of substitution (alpha or beta), number of substituent groups (4, 8, or 16), and presence or absence of metal (Zn or Al) in the center. For all phthalocyanines we find a moderately strong (sigma(2) approximately 100-200 GM), pure electronic, gerade-gerade (g-g) 2PA transition, which shows up as a well-resolved relatively narrow peak in the energy region between Q and B bands (lambda(ex)=870-1100 nm). In metallophthalocyanines (MPcs) this lowest g-g transition is followed by the onset of other higher-frequency 2PA transitions. In some metal-free phthalocyanines (H(2)Pcs) we also reveal a second, broader 2PA transition at slightly higher frequency. In both MPcs and H(2)Pcs, we find a strong monotonic increase of integrated strength of the lowest g-g transition as a function of electron-accepting ability of peripheral substituents, expressed as their aggregated Hammett constant. By using few essential states models (three states for MPcs and four states for H(2)Pcs) we demonstrate the primary role of excited-state transition dipole moment in this effect.

show abstract

Section: Two-photon Absorptionsupporting

confidence: 78%

Near-infrared two-photon absorption in phthalocyanines: Enhancement of lowest gerade-gerade transition by symmetrical electron-accepting substitution

Drobizhev

Makarov

Stepanenko

et al. 2006

The Journal of Chemical Physics

View full text Add to dashboard Cite

show abstract

“…In contrast, two-photon transitions are allowed between states of the same parity. Using quantum chemical methods, two-photon ππ* states for metal-free, Zn(II), and Mg(II) porphyrins were found at 30 000−33 000 cm -1 . − Two-photon fluorescence experiments found metal-free porphyrin two-photon states at similar energies. , In contrast, we find that much lower energy two-photon states are important for Fe(III) porphyrins. Fe(III) porphyrin film third-order nonlinear susceptibility is enhanced at least several times due to the charge-transfer states.…”

Section: Introductionmentioning

confidence: 69%

Charge-Transfer States Determine Iron Porphyrin Film Third-Order Nonlinear Optical Properties in the near-IR Spectral Region

Humphrey

Kuciauskas

2004

J. Phys. Chem. B

View full text Add to dashboard Cite

Femtosecond degenerate four-wave mixing (DFWM) was used to study third-order nonlinear optical properties of electropolymerized Fe(III) tetrakis(p-hydroxyphenyl)porphyrin films. Third-order nonlinear susceptibility χ 1111 (3) (-ω;ω,ω,-ω) was determined at 760-1350 nm. Susceptibility χ (3) values for a 500 nm thick porphyrin film ranged between (2-15)×10 -20 m 2 V -2 ((1.4-10.7)×10 -12 esu). The time response of electronic nonlinearities was faster than 120 fs. The sum-over-states model was applied to determine real and imaginary components for χ (3) and molecular second hyperpolarizability, γ. At wavelengths <800 nm, porphyrin film χ (3) is enhanced due to the 700 nm one-photon charge-transfer (CT) band. Nonlinear properties at longer wavelengths are determined by a two-photon resonance with a 17 400 cm -1 state. This state was not observed for other porphyrins and is attributed to a two-photon CT transition. Due to the resonance with the twophoton state, porphyrin Im χ (3) and two-photon absorption cross-section δ increased about 10 times when compared to values in the long-wavelength limit. Because of the contributions of the two-photon state, real component Re χ (3) had a negative sign in the near-IR spectral range; Re χ (3) ≈ -6×10 -20 m 2 V -2 at 9000-13 000 cm -1 . Results suggest that transition metal CT states can improve third-order nonlinear properties of organic materials.

show abstract

“…Four hundred singly excited electron configurations were taken into account (20 occupied MOs × 20 unoccupied MOs). Positive experience has been accumulated with calculations for porphyrin compounds based on such an approach [31][32][33][34][35].…”

Section: (Ii)mentioning

confidence: 99%

Electronic structure and spectra of NH-isomers of isobacteriochlorin

2006

View full text Add to dashboard Cite

ev UDC 539.19Using the restricted and unrestricted Hartree-Fock method (RHF and UHF) with the AM1 Hamiltonian, we have calculated the geometric structure of the NH-isomers of isobacteriochlorin and its meso-cyano derivative. We have used the CNDO/S method for all the considered structures to calculate the transitions to excited electronic states. We have analyzed the effect of taking into account electron correlation on the results of the calculations of the chemical and geometric structure and the electronic spectra. For the a isomer with the imino hydrogens opposite each other, we obtained a planar structure corresponding to literature x-ray diffraction data. For the aromatic c isomer and other isomers with the imino hydrogens adjacent to each other, the calculations lead to a substantial nonplanarity of the macrocycle (defined mainly by the tilt of the pyrrole rings) and also deviation of the NH bond from the plane of the pyrrole ring. The ground-state energies of the a and c isomers have close values, which generally explains the observed NH tautomerism. We calculated the dipole moments of the isomers in the ground state and the excited state. The results of the calculation of the characteristics of the excited states with UHF geometry on the whole seem to be preferred over those with RHF geometry. We show that only for the aromatic c isomer can we describe the electronic absorption spectrum within a four-orbital model.

show abstract

Untitled

Cited by 7 publications

References 16 publications

Near-infrared two-photon absorption in phthalocyanines: Enhancement of lowest gerade-gerade transition by symmetrical electron-accepting substitution

Near-infrared two-photon absorption in phthalocyanines: Enhancement of lowest gerade-gerade transition by symmetrical electron-accepting substitution

Charge-Transfer States Determine Iron Porphyrin Film Third-Order Nonlinear Optical Properties in the near-IR Spectral Region

Electronic structure and spectra of NH-isomers of isobacteriochlorin

Contact Info

Product

Resources

About