Molecular phosphorescence enhancement via tunneling through proton-transfer potentials

Journal Article · Thu Feb 08 04:00:00 EST 1990 · Journal of Physical Chemistry; (USA)

DOI:https://doi.org/10.1021/j100366a034· OSTI ID:6962725

Gormin, D; Heldt, J; Kasha, M ^[1]

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1. Florida State Univ., Tallahassee (USA)

A set of four substituted aminosalicylates, whose respective structures permit normal fluorescence, twisted intramolecular charge-transfer fluorescence, and proton-transfer fluorescence, in various combinations, were studied at 77 K to observe the effect on intersystem crossing. It is shown that the molecular structures which are capable of intramolecular proton transfer exhibit greatly enhanced normal molecule phosphorescence. The excitation mechanism involves proton-tunneling S{sub 1}{yields}S{sub 1}{prime}(PT) after primary excitation, enhanced intersystem crossing from the tautomer excited state S{sub 1}{prime}(PT){yields}T{sub 1}{prime}(PT), followed by reverse proton-transfer tunneling via triplet potential T{sub 1}{prime}(PT){yields}T{sub 1}. The competitive singlet-state excitation processes are delineated by picosecond transient absorption spectrometry. The mechanism described requires the specific electronic state energy ordering S{sub O} < S{sub O}{prime} < T{sub 1} < T{sub 1}{prime} < S{sub 1}{prime} < S{sub 1} {hor ellipsis} where the primes represent the states of the tautomer form of the molecule.

• DOE Contract Number: FG05-87ER60517
• OSTI ID: 6962725
• Journal Information: Journal of Physical Chemistry; (USA), Journal Name: Journal of Physical Chemistry; (USA) Vol. 94:3; ISSN 0022-3654; ISSN JPCHA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400500* -- Photochemistry
640302 -- Atomic
Molecular &amp; Chemical Physics-- Atomic &amp; Molecular Properties &amp; Theory
74 ATOMIC AND MOLECULAR PHYSICS
ABSORPTION SPECTROSCOPY
CALCULATION METHODS
CARBOXYLIC ACIDS
CHARGED-PARTICLE TRANSPORT
DATA ANALYSIS
ELECTRONIC STRUCTURE
ENERGY LEVELS
EXCITED STATES
HYDROXY ACIDS
LUMINESCENCE
MEASURING INSTRUMENTS
MEASURING METHODS
MOLECULES
ORGANIC ACIDS
ORGANIC COMPOUNDS
PHOSPHORESCENCE
PROTON TRANSPORT
RADIATION TRANSPORT
SALICYLIC ACID
SPECTROSCOPY
TUNNELING