Time-resolved high-frequency EPR studies on magnesium and zinc tetraphenylporphines in their lowest excited triplet states

Seigo Yamauchi, Katsuaki Takahashi, Saiful S.M. Islam, Yasunori Ohba, Valery Tarasov

研究成果: Article査読

13 被引用数 (Scopus)

抄録

The lowest excited triplet (T1) states of magnesium and zinc tetraphenylporphines (MgTPP and ZnTPP) were studied by time-resolved (TR) high-frequency/high-field W-band electron paramagnetic resonance (hf-EPR) spectroscopy in rigid glasses at low temperatures. Inspections of the TR-hf-EPR spectra of the spin-polarized triplets revealed that the zero field splitting (ZFS) parameters, D and E, for MgTPP and ZnTPP triplets were nearly the same. At the same time, their g-tensors were found to be different. These results are interpreted quantitatively in terms of spin - orbit couplings (SOCs) and angular momenta among the excited states, giving a magnitude of SOC in the T 1 state of ZnTPP. For the first time, both the TR-hf-EPR spectra and corresponding time profiles were acquired on the ZnTPP's triplet at room temperature in liquid paraffin solution with the populations of the electron spin states being in Boltzmann equilibrium. Because of relatively fast paramagnetic relaxation in rotating triplet at room temperature, the spectra and time profiles were free from the effects of microwave saturation that allowed for the direct measurement of the absolute intersystem crossing ratios P x·.Py·.Pz 0.085:0.085:0.83. All of these results have demonstrated advantages and new perspectives of the W-band EPR spectroscopy.

本文言語English
ページ(範囲)14559-14563
ページ数5
ジャーナルJournal of Physical Chemistry B
114
45
DOI
出版ステータスPublished - 2010 12 8

ASJC Scopus subject areas

  • 物理化学および理論化学
  • 表面、皮膜および薄膜
  • 材料化学

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