The scope of the Radiation Chemistry
Data Center (RCDC) was expanded in 1977 to include the collection of
papers containing quantitative data on photophysical and photochemical processes.
Since that time, several compilations have been prepared containing critically
evaluated data extracted from the literature referenced in our
bibliographic database
which also supports our compilation activities on the
kinetics (and other properties) of
free radicals.
Data compilations currently derive from three main areas:
- Excited (Organic) Triplet States
- Metal Complex Excited State Quenching
- Singlet Molecular Oxygen
A Handbook of Photochemistry containing
a much wider variety of photochemical and photophysical data has also been
published. (1993, Marcel Dekker)
The participation of the excited triplet state has been
implicated in a wide range of photochemical and photophysical processes.
Identification by spectral location and quantitification by molar absorption
coefficient calibration have been addressed in a compilation of
triplet-triplet absorption parameters, including a statistical analysis of
measured absorptivities, reviews of methodology and the selection of
recommended values.
Formation quantum yields, phosphorescence yields and decay rates have also been
compiled for key triplet states,
and extensive tabulations of further important properties, such as bimolecular
quenching rates, have been provided in the second edition of the
Handbook of Photochemistry.
- Molar absorption coefficients of transient species in solution
R. Bonneau, I. Carmichael, and G.L. Hug
Pure & Appl. Chem. 63 289-99 (1991)
A definitive review of methods for measuring the molar
absorptivity (aka extinction coefficient) of transient species in solution
commissioned by the Organic Chemistry Division (Commission on Photochemistry)
of the International Union of Pure and Applied Chemistry.
A table of recommended values for the benzophenone ketyl radical and a number of
important triplet state transients is included.
- Spectroscopy and intramolecular photophysics of triplet states
I. Carmichael and G.L. Hug
Handbook of Organic Photochemistry, vol. 1,J. C. Scaiano editor, (CRC Press, 1989) pp. 369-403
This review and compilation of the properties
of 149 key triplet states contains data at both room and low
(usually 77 K) temperatures.
Solvent effects are noted, distinguishing amongst benzenoid,
polar, and nonpolar media.
Data include:
Triplet state energies;
Wavelength maxima and extinction coefficients of triplet state absorption;
Decay rates of transient triplet absorbance;
Triplet state formation yields;
Phosphorescence quantum yields and decay times.
- Extinction coefficients of triplet-triplet absorption spectra of
organic molecules in condensed phases: A least-squares analysis
I. Carmichael, W.P. Helman and G.L. Hug
J. Phys. Chem. Ref. Data 16 239-60 (1987)
A global least-squares technique designed to handle large data
sets, comprising mainly of relative measurements, is developed and a linearization
procedure is used to reduce the inherently nonlinear
problem to a traditional multivariate linear regression.
The technique developed here is used to evaluate extinction
coefficients of triplet-triplet absorption (TTA) spectra of organic molecules
in condensed phases.
A previous assumption, that there are no solvent effects on the TTA spectra,
is investigated and modified so that a group of compounds measured in benzene is treated separately.
The set of 445 extinction coefficient values obtained from the global least-squares
fit is used in a hierarchy of TTA extinction coefficient standards.
Further solvent effects such as the separation of polar and nonpolar media and the influence of temperature are probed.
- Triplet-triplet absorption spectra of organic molecules in condensed phases
I. Carmichael and G.L. Hug
J. Phys. Chem. Ref. Data 15 1-250 (1986)
Published in 1986, this is an exhaustive compilation
of the spectral parameters (wavelengths and extinction coefficients - where known)
of excited triplet state absorption spectra for more than 1,100 organic species.
The compilation builds on earlier work of
Labhardt and Heinzelmann and Bensasson and Land and was followed by a
statistical evaluation (1987) which advocated a set of recommended values for
triplet-triplet extinction coefficients and outlined a three-level hierarchy of
reliability for the extant data.
The quenching of the excited
states of metal complexes, especially ruthenium tris(bipy), in solution is a
topic of central importance to solar photochemistry...
- Rate constants for the quenching of excited
states of metal complexes in fluid solution
M. Z. Hoffman, F. Bolletta, L. Moggi, and G. L. Hug
J. Phys. Ref Data 18 219-543 (1986)
An indicator of the importance of the quenching of excited states of metal
complexes is the recent domination of inorganic photochemistry by studies of
ruthenium(II) tris(2,2'-bipyridine), which can photosensitize electron transfer
reactions, and initiate solar photochemistry.
The rate constants for the quenching of the excited states of metal ions and
complexes in homogeneous fluid solution have been critically evaluated in this
compilation. The following information, among others, from the original
publications, is included when available: the solution medium, temperature,
experimental method, range of quencher concentration used, lifetime of the
excited state in the absence of quencher, and activation parameters. Quenching
mechanisms which are identified are:
collisional deactivation; chemical reaction; energy transfer;
exciplex formation; hydrogen abstraction; proton transfer;
oxidative electron transfer; reductive electron transfer.
Data collection is complete through the end of 1986, and covers the
coordination compounds of 26 metals, including the ions and complexes of the
inner- and outer-transition metals, and pophyrin complexes of non-transition
metals. Rate constants for 261 excited states quenched by over 400 inorganic
quenchers and 600 organic quenchers have been extracted from nearly 500
publications. A detailed discussion on the conceptual background to the
kinetics of quenching is included.
The first compilation derived from
photochemical bibliographic activity focused on the reaction rates
of singlet molecular oxygen and was published 1981;
an update and revision
of the original work.
Recently the quantum yields for the photoproduction
of singlet oxygen have also been collected and evaluated.
- Rate Constants for the Decay and Reactions of the
Lowest Electronically Excited Singlet State of Molecular Oxygen
in Solution. Revised and Expanded
F. Wilkinson, W. P. Helman, and A. B. Ross
J. Phys. Chem. Ref. Data 24 663-1021 (1995)
Reactions of singlet oxygen are of much current interest because of their
importance in photooxidations of chemical and biological systems, including
reactions used in photo-chemotherapy. Rate constants for the chemical reaction
and physical deactivation of singlet oxygen have been critically compiled from
the literature through 1993. Solvent deactivation rates are tabulated for 145
solvents and second-order rate constants for 1,915 compounds with singlet
oxygen are reported. This publication supersedes Wilkinson and Brummer, J.
Phys. Chem. Reference Data 10: 809 (1981).
Sixteen tables give rate constants or beta values with solvent, method,
and other details for reactions of singlet oxygen with:
olefins; aromatics; phenols and naphthols;
furans, pyrans and other heterocyclic oxygen compounds;
pyrroles, oxazoles, pyridines and other heterocyclic nitrogen compounds;
porphyrins, phthalocyanines and polypyrroles;
aliphatic and alicyclic amines;
aromatic amines; amino acids, peptides and proteins;
diazo compounds and dyes; metal complexes;
sulfur, selenium and tellurium compounds; inorganic compounds;
oximes, hydrazones, nitrones, nitroso compounds and N-oxides;
some compounds of biological interest; miscellaneous substrates.
- Quantum Yields for the Photosensitized Formation of the
Lowest Electronically Excited Singlet State of Molecular Oxygen
in Solution
F. Wilkinson, W. P. Helman, and A. B. Ross
J. Phys. Chem. Ref. Data 22 113-262 (1993)
Photosensitized oxidations involving singlet oxygen are implicated in
photodynamic inactivation of viruses and cells, in phototherapy for cancer,
in photocarcinogenesis and in photodegradation of dyes and polymers.
Quenching of excited singlet and triplet states of many substances by ground
state molecular oxygen produces singlet oxygen, the lowest electronically
excited singlet state of molecular oxygen. The fractions of singlet and triplet
states quenched which produce singlet oxygen and the quantum yields of
formation of singlet oxygen in fluid solutions have been critically compiled.
Methods for determining yield parameters have been reviewed. Data have been
compiled from the literature through 1991.
Data are tabulated for 754 substances, such as the following categories
of photosensitizers:
aromatic hydrocarbons; aromatic ketones and thiones; quinones;
coumarins; fluoresceins; transition metal complexes; heterocyclics;
porphyrins and phthalocyanines; dyes; drugs.
S.L. Murov, I. Carmichael, and G.L. Hug
Second Edition, Marcel Dekker, publisher (1993), 420p.
Presenting material in timesaving,
easy-to-use tables organized to facilitate typical experimental
procedures, the Handbook of Photochemistry, Second Edition
contains extensive new information on topics such as
fluorescence quantum yields and lifetimes ... triplet formation
yields, extinction coefficients and decay rates ...
triplet energies for more than 1000 organic species ...
bimolecular quenching rates ... zero-field splitting parameters ...
redox potentials ... and more
The Second edition of the
Handbook of Photochemistry is a heavily revised and
much expanded version of Murov's original work published in 1973
by Marcel Dekker.
e-mail: madden.1@nd.edu
