Ligand-Centred Fluorescence and Electronic Relaxation Cascade at Vibrational Time Scales in Transition-Metal Complexes

Fabrizio Messina, Etienne Baranoff, Fabrizio Messina, Enrico Pomarico, Mahsa Silatani, Majed Chergui

Risultato della ricerca: Article

16 Citazioni (Scopus)

Abstract

Using femtosecond-resolved photoluminescence up-conversion, we report the observation of the fluorescence of the high-lying ligand-centered (LC) electronic state upon 266 nm excitation of an iridium complex, Ir(ppy)3, with a lifetime of 70 ± 10 fs. It is accompanied by a simultaneous emission of all lower-lying electronic states, except the lowest triplet metal-to-ligand charge-transfer (3MLCT) state that shows a rise on the same time scale. Thus, we observe the departure, the intermediate steps, and the arrival of the relaxation cascade spanning ∼1.6 eV from the 1LC state to the lowest 3MLCT state, which then yields the long-lived luminescence of the molecule. This represents the first measurement of the total relaxation time over an entire cascade of electronic states in a polyatomic molecule. We find that the relaxation cascade proceeds in ≈10 fs, which is faster than some of the highest-frequency modes of the system. We invoke the participation of the latter modes in conical intersections and their overdamping to low-frequency intramolecular modes. On the basis of literature, we also conclude that this behavior is not specific to transition-metal complexes but also applies to organic molecules.
Lingua originaleEnglish
pagine (da-a)4475-4480
Numero di pagine6
RivistaTHE JOURNAL OF PHYSICAL CHEMISTRY LETTERS
Volume6
Stato di pubblicazionePublished - 2015

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Coordination Complexes
Electronic states
Metal complexes
Transition metals
Fluorescence
Ligands
Molecules
Iridium
Relaxation time
Charge transfer
Luminescence
Photoluminescence
Metals

All Science Journal Classification (ASJC) codes

  • Materials Science(all)

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Ligand-Centred Fluorescence and Electronic Relaxation Cascade at Vibrational Time Scales in Transition-Metal Complexes. / Messina, Fabrizio; Baranoff, Etienne; Messina, Fabrizio; Pomarico, Enrico; Silatani, Mahsa; Chergui, Majed.

In: THE JOURNAL OF PHYSICAL CHEMISTRY LETTERS, Vol. 6, 2015, pag. 4475-4480.

Risultato della ricerca: Article

Messina, Fabrizio ; Baranoff, Etienne ; Messina, Fabrizio ; Pomarico, Enrico ; Silatani, Mahsa ; Chergui, Majed. / Ligand-Centred Fluorescence and Electronic Relaxation Cascade at Vibrational Time Scales in Transition-Metal Complexes. In: THE JOURNAL OF PHYSICAL CHEMISTRY LETTERS. 2015 ; Vol. 6. pagg. 4475-4480.
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abstract = "Using femtosecond-resolved photoluminescence up-conversion, we report the observation of the fluorescence of the high-lying ligand-centered (LC) electronic state upon 266 nm excitation of an iridium complex, Ir(ppy)3, with a lifetime of 70 ± 10 fs. It is accompanied by a simultaneous emission of all lower-lying electronic states, except the lowest triplet metal-to-ligand charge-transfer (3MLCT) state that shows a rise on the same time scale. Thus, we observe the departure, the intermediate steps, and the arrival of the relaxation cascade spanning ∼1.6 eV from the 1LC state to the lowest 3MLCT state, which then yields the long-lived luminescence of the molecule. This represents the first measurement of the total relaxation time over an entire cascade of electronic states in a polyatomic molecule. We find that the relaxation cascade proceeds in ≈10 fs, which is faster than some of the highest-frequency modes of the system. We invoke the participation of the latter modes in conical intersections and their overdamping to low-frequency intramolecular modes. On the basis of literature, we also conclude that this behavior is not specific to transition-metal complexes but also applies to organic molecules.",
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TY - JOUR

T1 - Ligand-Centred Fluorescence and Electronic Relaxation Cascade at Vibrational Time Scales in Transition-Metal Complexes

AU - Messina, Fabrizio

AU - Baranoff, Etienne

AU - Messina, Fabrizio

AU - Pomarico, Enrico

AU - Silatani, Mahsa

AU - Chergui, Majed

PY - 2015

Y1 - 2015

N2 - Using femtosecond-resolved photoluminescence up-conversion, we report the observation of the fluorescence of the high-lying ligand-centered (LC) electronic state upon 266 nm excitation of an iridium complex, Ir(ppy)3, with a lifetime of 70 ± 10 fs. It is accompanied by a simultaneous emission of all lower-lying electronic states, except the lowest triplet metal-to-ligand charge-transfer (3MLCT) state that shows a rise on the same time scale. Thus, we observe the departure, the intermediate steps, and the arrival of the relaxation cascade spanning ∼1.6 eV from the 1LC state to the lowest 3MLCT state, which then yields the long-lived luminescence of the molecule. This represents the first measurement of the total relaxation time over an entire cascade of electronic states in a polyatomic molecule. We find that the relaxation cascade proceeds in ≈10 fs, which is faster than some of the highest-frequency modes of the system. We invoke the participation of the latter modes in conical intersections and their overdamping to low-frequency intramolecular modes. On the basis of literature, we also conclude that this behavior is not specific to transition-metal complexes but also applies to organic molecules.

AB - Using femtosecond-resolved photoluminescence up-conversion, we report the observation of the fluorescence of the high-lying ligand-centered (LC) electronic state upon 266 nm excitation of an iridium complex, Ir(ppy)3, with a lifetime of 70 ± 10 fs. It is accompanied by a simultaneous emission of all lower-lying electronic states, except the lowest triplet metal-to-ligand charge-transfer (3MLCT) state that shows a rise on the same time scale. Thus, we observe the departure, the intermediate steps, and the arrival of the relaxation cascade spanning ∼1.6 eV from the 1LC state to the lowest 3MLCT state, which then yields the long-lived luminescence of the molecule. This represents the first measurement of the total relaxation time over an entire cascade of electronic states in a polyatomic molecule. We find that the relaxation cascade proceeds in ≈10 fs, which is faster than some of the highest-frequency modes of the system. We invoke the participation of the latter modes in conical intersections and their overdamping to low-frequency intramolecular modes. On the basis of literature, we also conclude that this behavior is not specific to transition-metal complexes but also applies to organic molecules.

KW - electronic relaxation; fluorescence up-conversion; iridium complexes; ligand-centered fluorescence; ultrafast; Materials Science (all)

UR - http://hdl.handle.net/10447/226804

UR - http://pubs.acs.org/journal/jpclcd

M3 - Article

VL - 6

SP - 4475

EP - 4480

JO - Journal of Physical Chemistry Letters

JF - Journal of Physical Chemistry Letters

SN - 1948-7185

ER -