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Light-induced spin crossover probed by ultrafast optical and X-ray spectroscopies

Gawelda, Wojciech ; Cannizzo, Andrea ; El Nahhas, Amal LU ; Milne, Christopher J. ; Van Der Veen, Renske ; Bressler, Christian ; Chergui, Majed and Pham, Van-Thai LU (2007) In Chimia 61(4). p.179-183
Abstract

The photoinduced energy and structural relaxation of aqueous iron(II)-tris-bipyridine ([FeII(bpy)3]2+), upon excitation into its singlet metal-to-ligand charge transfer (1MLCT) band, and the population of its short-lived (≤0.6 ns) high-spin excited state have been characterized by combined ultrafast optical and X-ray spectroscopies. Polychromatic femtosecond fluorescence up-conversion reveals a very short lived 1MLCT emission band, which decays in ≤20 fs by intersystem crossing to a 3MLCT, whose very weak emission is also observed. Transient absorption studies show that the latter decays in <150 fs, while the population of the lowest excited high spin quintet state... (More)

The photoinduced energy and structural relaxation of aqueous iron(II)-tris-bipyridine ([FeII(bpy)3]2+), upon excitation into its singlet metal-to-ligand charge transfer (1MLCT) band, and the population of its short-lived (≤0.6 ns) high-spin excited state have been characterized by combined ultrafast optical and X-ray spectroscopies. Polychromatic femtosecond fluorescence up-conversion reveals a very short lived 1MLCT emission band, which decays in ≤20 fs by intersystem crossing to a 3MLCT, whose very weak emission is also observed. Transient absorption studies show that the latter decays in <150 fs, while the population of the lowest excited high spin quintet state 5T 2 occurs in ∼1 ps. Subsequently it decays in ∼665 ps to the ground state. Therefore, we determined the structure of the high-spin excited state by picosecond X-ray absorption spectroscopy at the K edge of Fe. The structural analysis of both the transient difference and excited state X-ray spectra delivered an Fe-N bond elongation of 0.2 Å in the quintet state compared to the singlet ground state.

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author
; ; ; ; ; ; and
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Fluorescence, Iron (II) complexes, Optical absorption, Spin crossover, Ultrafast, X-ray absorption
in
Chimia
volume
61
issue
4
pages
5 pages
publisher
Swiss Chemical Society
external identifiers
  • scopus:34248549685
ISSN
0009-4293
DOI
10.2533/chimia.2007.179
language
English
LU publication?
no
id
e3c8d03e-d1d9-41fe-b894-d281a1def0b8
date added to LUP
2019-06-30 10:03:08
date last changed
2022-01-31 23:00:53
@article{e3c8d03e-d1d9-41fe-b894-d281a1def0b8,
  abstract     = {{<p>The photoinduced energy and structural relaxation of aqueous iron(II)-tris-bipyridine ([Fe<sup>II</sup>(bpy)<sub>3</sub>]<sup>2+</sup>), upon excitation into its singlet metal-to-ligand charge transfer (<sup>1</sup>MLCT) band, and the population of its short-lived (≤0.6 ns) high-spin excited state have been characterized by combined ultrafast optical and X-ray spectroscopies. Polychromatic femtosecond fluorescence up-conversion reveals a very short lived <sup>1</sup>MLCT emission band, which decays in ≤20 fs by intersystem crossing to a <sup>3</sup>MLCT, whose very weak emission is also observed. Transient absorption studies show that the latter decays in &lt;150 fs, while the population of the lowest excited high spin quintet state <sup>5</sup>T <sub>2</sub> occurs in ∼1 ps. Subsequently it decays in ∼665 ps to the ground state. Therefore, we determined the structure of the high-spin excited state by picosecond X-ray absorption spectroscopy at the K edge of Fe. The structural analysis of both the transient difference and excited state X-ray spectra delivered an Fe-N bond elongation of 0.2 Å in the quintet state compared to the singlet ground state.</p>}},
  author       = {{Gawelda, Wojciech and Cannizzo, Andrea and El Nahhas, Amal and Milne, Christopher J. and Van Der Veen, Renske and Bressler, Christian and Chergui, Majed and Pham, Van-Thai}},
  issn         = {{0009-4293}},
  keywords     = {{Fluorescence; Iron (II) complexes; Optical absorption; Spin crossover; Ultrafast; X-ray absorption}},
  language     = {{eng}},
  month        = {{05}},
  number       = {{4}},
  pages        = {{179--183}},
  publisher    = {{Swiss Chemical Society}},
  series       = {{Chimia}},
  title        = {{Light-induced spin crossover probed by ultrafast optical and X-ray spectroscopies}},
  url          = {{http://dx.doi.org/10.2533/chimia.2007.179}},
  doi          = {{10.2533/chimia.2007.179}},
  volume       = {{61}},
  year         = {{2007}},
}