Spectrally resolved photon echo spectroscopy of Zn(II), Co(II) and Ni(II)–octaethyl porphyrins

Spectrally resolved femtosecond three-pulse photon echo signal from some metal–octaethyl porphyrins (OEPs) like Zn(II)–OEP, Ni(II)–OEP, Co(II)–OEP is reported. Excited state dynamics is studied by time evolving photon echo spectra for different values of coherence and population relaxation times. Dependence on the spectrally resolved photon echo spectra on varying metal center is analyzed. For all these metallo-porphyrins, the electronic relaxation timescale is found to be limited by our laser pulsewidth of 50 fs whereas the timescale for intramolecular vibrational relaxation, occurring within the Q00 band was found to be over a picosecond for Co(II)–OEP and Ni(II)–OEP and within a picosecond for Zn(II)–OEP.