title: Visible luminescence spectroscopy of free-base and zinc phthalocyanines isolated in cryogenic matrices.
abstract: The absorption, emission and excitation spectra of ZnPc and H(2)Pc trapped in Ne, N(2), Ar, Kr and Xe matrices have been recorded in the region of the Q states. A comparison of the matrix fluorescence spectra with Raman spectra recorded in KBr pellets reveals very strong similarities. This is entirely consistent with the selection rules and points to the occurrence of only fundamental vibrational transitions in the emission spectra. Based on this behaviour, the vibronic modes in emission have been assigned using results obtained recently on the ground state with large basis-set DFT calculations [Murray et al. PCCP, 12, 10406 (2010)]. Furthermore, the very strong mirror symmetry between excitation and emission has allowed these assignments to be extended to the excitation (absorption) bands. While this approach works well for ZnPc, coupling between the band origin of the S(2)(Q(Y)) state and vibrationally excited levels of S(1)(Q(X)), limits the range of its application in H(2)Pc. The Q(X)/Q(Y) state coupling is analysed from data obtained from site-selective excitation spectra, revealing pronounced matrix and site effects. From this analysis, the splitting of the Q(X) and Q(Y) states has been determined more accurately than in any previous attempts.
authors: Department of Chemistry, National University of Ireland - Maynooth, Co. Kildare, Ireland.
authors: Ciaran
authors: C
authors: Murray
authors: Nadia
authors: N
authors: Dozova
authors: John G
authors: JG
authors: McCaffrey
authors: Niloufar
authors: N
authors: Shafizadeh
authors: Wuthurath
authors: W
authors: Chin
authors: Michel
authors: M
authors: Broquier
authors: Claudine
authors: C
authors: Crépin
mesh_terms: D007211:Indoles / Q000737:chemistry* / Q000302:isolation & purification*; D054833:Isoindoles; D008163:Luminescent Measurements; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000302:isolation & purification*; D011789:Quantum Theory; D013237:Stereoisomerism; D017967:Zinc Compounds
chemical_list: D007211:Indoles; D054833:Isoindoles; D009942:Organometallic Compounds; D017967:Zinc Compounds; C052159:Zn(II)-phthalocyanine; C013647:phthalocyanine