A precise determination of the triplet energy of C sub 60 by photoacoustic calorimetry

Journal Article · Thu Aug 08 04:00:00 EDT 1991 · Journal of Physical Chemistry; (United States)

DOI:https://doi.org/10.1021/j100169a007· OSTI ID:7017353

Hung, R R; Grabowski, J J ^[1]

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1. Harvard Univ., Cambridge, MA (United States)

The relatively new technique of time-resolved, pulsed-laser photoacoustic calorimetry has been exploited to precisely determine the triplet-state energy of C{sub 60}, the newly discovered spheroidal allotrope of carbon. Excitation at 510 nm, in the long-wavelength absorption band of C{sub 60}, produces C{sub 60}(T{sub 1}) with unit efficiency; in the presence of dioxygen, triplet C{sub 60} is readily quenched by energy transfer. Photoacoustic waves were recorded for C{sub 60} in argon-saturated, air-saturated, and partially argon-saturated toluene solutions. Each experimental wave was then fit to a two-component model, the first component of which corresponds to production of C{sub 60}(T{sub 1}) and the second of which relates to its decay. The recovered heat-deposition parameters are {phi}{sub 1} = 0.359 {plus minus} 0.005 and {phi}{sub 2} = 0.237 {plus minus} 0.011; these correspond to the fraction of the absorbed photon energy that is released in forming C{sub 60}(T{sub 1}) and in the quenching of C{sub 60}(T{sub 1}) by dioxygen. Since the quantum yield for intersystem crossing of C{sub 60}, from S{sub 1} to T{sub 1}, is unity, {phi}{sub 1} corresponds to a C{sub 60}(T{sub 1}) energy of 36.0 {plus minus} 0.6 kcal mol{sup {minus}1}. Since the energy of C{sub 60}(T{sub 1}) is defined by {phi}{sub 1} and the energy of O{sub 2}({sup 1}{Delta}) is known {phi}{sub 2} is used to calculate a singlet oxygen sensitization quantum yield of 1.01 {plus minus} 0.03. The lifetime of C{sub 60}(T{sub 1}) in argon-saturated toluene is found to be > 10 {mu}s, and in air-saturated toluene, to be 290 {plus minus} 40 ns.

• OSTI ID: 7017353
• Journal Information: Journal of Physical Chemistry; (United States), Journal Name: Journal of Physical Chemistry; (United States) Vol. 95:16; ISSN 0022-3654; ISSN JPCHA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
400800 -- Combustion
Pyrolysis
& High-Temperature Chemistry
CALORIMETRY
CARBON
DATA
DATA ANALYSIS
ELECTRONIC STRUCTURE
ELEMENTS
ENERGY LEVELS
ENERGY TRANSFER
EXPERIMENTAL DATA
FULLERENES
INFORMATION
KINETICS
LASER SPECTROSCOPY
NONMETALS
NUMERICAL DATA
OXYGEN
PHOTOACOUSTIC SPECTROSCOPY
QUENCHING
RESOLUTION
SPECTROSCOPY
TIME RESOLUTION
TIMING PROPERTIES