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THE QUANTUM EFFICIENCY OF THE PHOTO-EXCITATION IN A Fe (II) SPIN-CROSSOVER COMPOUND

C. Enachescu1,2,* , U. Oetliker1, A. Hauser1

Affiliation

  1. Département de chimie physique, Université de Genève CH-1211 Genève, Switzerland
  2. Faculty of physics, “Al. I. Cuza” University, Iasi, 6600, Romania

Abstract

In this paper we discuss on the quantum efficiency in spin crossover compounds. Spin crossover solids are text-book examples of photo switchable materials that present a thermal spin transition from the diamagnetic low-spin state, thermodynamically stable at low temperatures, to the paramagnetic high-spin state becoming the thermodynamically stable state at elevated temperature. By irradiating them with an appropriate wavelength, they can pass from the stable low spin state to the metastable high spin state at temperatures below the thermal transition temperature. For the compound [Fe(pic)3]Cl2·EtOH, the question regarding the quantum efficiency of the photo-conversion process that is the number of molecules converted by one single photon and its possible dependency on irradiation intensity gave rise to a controversy. The experimental results presented in this paper demonstrate that the quantum efficiency of the photo-conversion at 11 K is on the order of unity, with no noticeable dependency of the quantum efficiency on light intensity. It does, however, depend to a small extent on the fraction of complexes already converted to the high-spin state..

Keywords

Spin transition, Quantum efficiency, Spin transition compounds.

Submitted at: July 23, 2002
Accepted at: March 12, 2003

Citation

C. Enachescu, U. Oetliker, A. Hauser, THE QUANTUM EFFICIENCY OF THE PHOTO-EXCITATION IN A Fe (II) SPIN-CROSSOVER COMPOUND, Journal of Optoelectronics and Advanced Materials Vol. 5, Iss. 1, pp. 267-272 (2003)