Density functional theory study of vibronic structure of the first absorption Qx band in free-base porphin
2006 (English)In: Spectrochimica Acta Part A - Molecular and Biomolecular Spectroscopy, ISSN 1386-1425, Vol. 65, no 2, 308-323 p.Article in journal (Refereed) Published
Harmonic vibrational frequencies and vibronic intensities in the first S-0 -> S-1 (pi pi*) absorption band of free-base porphin (H2P) are investigated by hybrid density functional theory (DFT) with the standard B3LYP functional. The S-0-S-1 transition probability is calculated using time-dependent DFT with account of Franck-Condon (FC) and Herzberg-Teller (HT) contributions to the electric-dipole transition moments including displacements along all 108 vibrational modes. Two weak wide bands observed in the gas phase absorption spectra of the H2P molecule at 626 and 576 nm are interpreted as the 0-0 band of the X(1)A(g)-> B-3u transition and the 0-1 band with largest contributions from the nu(10)(a(g)) = 1610 cm(-1) and nu(19)(b(1g)) = 1600 cm(-1) modes, respectively, in agreement with previous tentative assignments. Both bands are induced by the HT mechanism, while the FC contributions are negligible. A number of fine structure bands, including combination of two vibrational quanta, are obtained and compared with available spectra from supersonic jet and Shpolskij matrices. Both absorption and fluorescence spectra are interpreted on ground of the linear coupling model and a good fulfillment of the mirror-symmetry rule.
Place, publisher, year, edition, pages
2006. Vol. 65, no 2, 308-323 p.
Absorption; Electronic structure; Fluorescence; Harmonic analysis; Lattice vibrations; Mathematical models; Probability density function; Electric-dipole transition moments; Harmonic vibrational frequencies; Porphin; Vibronic coupling; Aromatic compounds; porphine; porphyrin; article; chemical model; chemical structure; chemistry; computer assisted emission tomography; fluorescence; infrared spectrophotometry; infrared spectroscopy; light; luminescence; mathematics; physical chemistry; quantum theory; Raman spectrometry; spectroscopy; ultraviolet spectrophotometry; vibration; Chemistry, Physical; Fluorescence; Light; Luminescent Measurements; Mathematics; Models, Chemical; Models, Molecular; Porphyrins; Quantum Theory; Spectrophotometry, Infrared; Spectrophotometry, Ultraviolet; Spectroscopy, Fourier Transform Infrared; Spectrum Analysis; Spectrum Analysis, Raman; Tomography, Emission-Computed; Vibration
IdentifiersURN: urn:nbn:se:kth:diva-6976DOI: 10.1016/j.saa.2005.10.047ISI: 000240692400010ScopusID: 2-s2.0-33747880113OAI: oai:DiVA.org:kth-6976DiVA: diva2:11841
QC 201008202007-04-162007-04-162010-08-20Bibliographically approved