Phosphorescence of vitreous 2-bromobenzophenone
Spectroscopic studies of vitreous 2-bromobenzophenone have been carried out over the respective domain of its stability. Glassy 2-bromobenzophenone samples were obtained by abrupt cooling of the melt by cold helium vapor. Quantum yield measurements allowed us to establish that the upper boundary o...
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irk-123456789-1169782017-05-19T03:03:35Z Phosphorescence of vitreous 2-bromobenzophenone Buravtseva, L.M. Pyshkin, O.S. Strzhemechny, M.A. Avdeenko, A.A. Низкоразмерные и неупорядоченные системы Spectroscopic studies of vitreous 2-bromobenzophenone have been carried out over the respective domain of its stability. Glassy 2-bromobenzophenone samples were obtained by abrupt cooling of the melt by cold helium vapor. Quantum yield measurements allowed us to establish that the upper boundary of stable glass is slightly above 100 K while at about 220 K the glass melts. Phosphorescence measurements at 4.2 K showed that even at this low temperature the emission contains a strong excimer component. The energy position and shape (two bands) of the excimer emission are close to those observed in the crystal of 2-bromobenzophenone at higher temperatures. Contrary to findings in the crystal, the monomeric emission of the glass contains only one C=O stretch series, every band of which is substantially broader than in the crystal. As the temperature is raised, the monomeric emission intensity goes down to completely disappear above 70 K. 2008 Article Phosphorescence of vitreous 2-bromobenzophenone / L.M. Buravtseva, O.S. Pyshkin, M.A. Strzhemechny, A.A. Avdeenko // Физика низких температур. — 2008. — Т. 34, № 6. — С. 587–591. — Бібліогр.: 16 назв. — англ. 0132-6414 PACS: 33.50.Dq;78.55.Qr http://dspace.nbuv.gov.ua/handle/123456789/116978 en Физика низких температур Фізико-технічний інститут низьких температур ім. Б.І. Вєркіна НАН України |
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Digital Library of Periodicals of National Academy of Sciences of Ukraine |
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Низкоразмерные и неупорядоченные системы Низкоразмерные и неупорядоченные системы |
| spellingShingle |
Низкоразмерные и неупорядоченные системы Низкоразмерные и неупорядоченные системы Buravtseva, L.M. Pyshkin, O.S. Strzhemechny, M.A. Avdeenko, A.A. Phosphorescence of vitreous 2-bromobenzophenone Физика низких температур |
| description |
Spectroscopic studies of vitreous 2-bromobenzophenone have been carried out over the respective domain
of its stability. Glassy 2-bromobenzophenone samples were obtained by abrupt cooling of the melt by
cold helium vapor. Quantum yield measurements allowed us to establish that the upper boundary of stable
glass is slightly above 100 K while at about 220 K the glass melts. Phosphorescence measurements at 4.2 K
showed that even at this low temperature the emission contains a strong excimer component. The energy position
and shape (two bands) of the excimer emission are close to those observed in the crystal of
2-bromobenzophenone at higher temperatures. Contrary to findings in the crystal, the monomeric emission
of the glass contains only one C=O stretch series, every band of which is substantially broader than in the
crystal. As the temperature is raised, the monomeric emission intensity goes down to completely disappear
above 70 K. |
| format |
Article |
| author |
Buravtseva, L.M. Pyshkin, O.S. Strzhemechny, M.A. Avdeenko, A.A. |
| author_facet |
Buravtseva, L.M. Pyshkin, O.S. Strzhemechny, M.A. Avdeenko, A.A. |
| author_sort |
Buravtseva, L.M. |
| title |
Phosphorescence of vitreous 2-bromobenzophenone |
| title_short |
Phosphorescence of vitreous 2-bromobenzophenone |
| title_full |
Phosphorescence of vitreous 2-bromobenzophenone |
| title_fullStr |
Phosphorescence of vitreous 2-bromobenzophenone |
| title_full_unstemmed |
Phosphorescence of vitreous 2-bromobenzophenone |
| title_sort |
phosphorescence of vitreous 2-bromobenzophenone |
| publisher |
Фізико-технічний інститут низьких температур ім. Б.І. Вєркіна НАН України |
| publishDate |
2008 |
| topic_facet |
Низкоразмерные и неупорядоченные системы |
| url |
http://dspace.nbuv.gov.ua/handle/123456789/116978 |
| citation_txt |
Phosphorescence of vitreous 2-bromobenzophenone / L.M. Buravtseva, O.S. Pyshkin, M.A. Strzhemechny, A.A. Avdeenko // Физика низких температур. — 2008. — Т. 34, № 6. — С. 587–591. — Бібліогр.: 16 назв. — англ. |
| series |
Физика низких температур |
| work_keys_str_mv |
AT buravtsevalm phosphorescenceofvitreous2bromobenzophenone AT pyshkinos phosphorescenceofvitreous2bromobenzophenone AT strzhemechnyma phosphorescenceofvitreous2bromobenzophenone AT avdeenkoaa phosphorescenceofvitreous2bromobenzophenone |
| first_indexed |
2025-07-08T11:26:03Z |
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2025-07-08T11:26:03Z |
| _version_ |
1837077851738734592 |
| fulltext |
Fizika Nizkikh Temperatur, 2008, v. 34, No. 6, p. 587–591
Phosphorescence of vitreous 2-bromobenzophenone
L.M. Buravtseva, O.S. Pyshkin, M.A. Strzhemechny, and A.A. Avdeenko
B. Verkin Institute for Low Temperature Physics and Engineering of the National Academy of Sciences of Ukraine
47 Lenin Ave., Kharkov 61103, Ukraine
E-mail: buravtseva@ilt.kharkov.ua
Received November 13, 2007 , revised December 21, 2007
Spectroscopic studies of vitreous 2-bromobenzophenone have been carried out over the respective do-
main of its stability. Glassy 2-bromobenzophenone samples were obtained by abrupt cooling of the melt by
cold helium vapor. Quantum yield measurements allowed us to establish that the upper boundary of stable
glass is slightly above 100 K while at about 220 K the glass melts. Phosphorescence measurements at 4.2 K
showed that even at this low temperature the emission contains a strong excimer component. The energy po-
sition and shape (two bands) of the excimer emission are close to those observed in the crystal of
2-bromobenzophenone at higher temperatures. Contrary to findings in the crystal, the monomeric emission
of the glass contains only one C=O stretch series, every band of which is substantially broader than in the
crystal. As the temperature is raised, the monomeric emission intensity goes down to completely disappear
above 70 K.
PACS: 33.50.Dq Fluorescence and phosphorescence spectra;
78.55.Qr Amorphous materials; glasses and other disordered solids.
Keywords: 2-bromobenzophenone glass, photoluminescence, quantum yield, excimer.
1. Introduction
Photoluminescence spectra [1] of 2-bromobenzophe-
none (ortho-bromobenzophenone) crystals at low temper-
atures in no way resemble those of any other representa-
tives of the benzophenone family studied up to date,
namely, unsubstituted benzophenone (see, for example,
Melnik [2]), 44�-dichlorobenzophenone [3,4], 4-bromo-
benzophenone (as preliminarily quoted in our previous
paper [1]). The low-temperature phosphorescence spec-
trum of the 2-bromobenzophenone crystal comprises very
broad monomer C=O stretch repetition bands, devoid of
any traces of the rich substructure of the spectra of the
other above-mentioned crystalline benzophenones, in
which a coherently traveling triplet exciton emits on vari-
ous traps (lattice imperfections, etc.). This gives grounds
to suspect that triplet exciton transport (see the relevant
review by Fayer [5]) in 2-bromobenzophenone is essen-
tially suppressed. One way to check this inference is by
measuring phosphorescence properties in the glassy state,
if such exists. Luckily, in 2-bromobenzophenone it does.
Now, in order to check whether any detectable triplet
exciton transport exists in 2-bromobenzophenone,we are
to rely on the long-standing theory and practice [6] re-
garding such transport in dispersive media, especially in
unsubstituted vitreous benzophenone [7–10], using
time-resolved phosphorescence measurements. On the way
to this ultimate goal we had to study in sufficient detail
morphology relaxation as well as the optical properties of
the glass state of 2-bromobenzophenone. These results
constitute the subject of this paper. Detailed time-resolv-
ed phosphorescence spectra in vitreous and crystalline
2-bromobenzophenone will be published later [11].
2. Experimental
As previously reported [2], 2-bromobenzophenone
crystallizes very reluctantly from the melt and can easily
vitrify by itself with decreasing temperature. In these
studies, ortho-bromobenzophenone was purified by mul-
tiple recrystallization from ethanol. Vitreous samples ap-
proximately 1.5 mm thick were prepared in situ as fol-
lows. A certain amount of pure crystalline matter was
placed in a transparent flat quartz container with a heater
wound outside at its bottom. The container was then se-
cured in the lower chamber of a liquid helium flow
cryostat. The container was heated till the crystalline
sample melted, after which the container with the melt
inside was cooled abruptly by helium vapor.
© L.M. Buravtseva, O.S. Pyshkin, M.A. Strzhemechny, and A.A. Avdeenko, 2008
Luminescence spectra were recorded using a DFS-12
automated double monochromator (linear dispersion
5.2 �/mm) and a cooled FEU-106 counter in the photon
count mode. Phosphorescence spectra were corrected to
account for the varying spectral sensitivity of the record-
ing equipment. If not otherwise stated, all spectra are nor-
malized to unity at maximum value of the respective
trace. The spectral slit width did not exceed 0.5 � for all
measurements. Sample excitation was performed with a
LGI-21 nitrogen laser, generation wavelength 337.1 nm,
pulse duration 10 ns, pulse sequence frequency 100 Hz,
pulse power flux 20 kW/cm2. Spectra of glass samples
were recorded from 4.2 to 95 K. The temperature, main-
tained constant during experiments to within � 1 K by an
electronic stabilizer, was measured with a semiconductor
thermometer.
Relative quantum yield measurements were performed
by exciting the sample with a single pulse of the LGI-21
nitrogen laser. Registration of the total number of photons
emitted by excited glassy 2-bromobenzophenone after a
single excitation pulse was performed using a quantum
counter based on a glycol solution of rhodamine-B.
3. Results and discussion
3.1. Characterization of the vitreous state
When working with a disordered state (like the
2-bromobenzophenone glass), which is possibly prone to
spontaneous morphologic changes, it is advisable to es-
tablish the domain of its stable existence and to determine
the relevant relaxation times close to and beyond that do-
main. To this end, several independent spectral experi-
ments have been carried out.
First, knowing that relative quantum yield can be a suf-
ficiently sensitive means for the above purpose we mea-
sured it as a function of temperature from 4.2 to 250 K.
The rate of temperature increase was approximately
1 K/min. The respective results are depicted in Fig. 1. In
the inset we compare the non-normalized quantum yields
of glassy and crystalline 2-bromobenzophenone, both
curves registered under the same excitation/collection
conditions. The emission of the glassy state is consider-
ably weaker (especially, above 100 K) and does not ex-
hibit the low-temperature maximum, which is character-
istic of the crystalline state. It is generally accepted [9,13]
that the maximum in the crystal emission can be ex-
plained as a crossover between the phonon-assisted
growth of emissionless transitions at higher temperatures
and a similar quenching owing to traps at lower tempera-
tures when the role of triplet exciton transport increases.
A blowup of the normalized lower curve for the glassy
state in the inset is shown in the main plot of Fig. 1. It is
clearly seen that there are two «critical» points where the
sample morphology suffers changes. One point labeled 1
(at about 100 K) can be treated as the temperature where
the glass looses its stability, undergoing some morpho-
logic changes. This process stops at point 2 (about
220 K), above which the appearing state is the liquid
state, which could be observed with the naked eye. This
critical point is the vitrification/liquification temperature.
As the temperature grew further to 300 K, the sample did
not crystallize. Even at room temperature it remained liq-
uid for quite a long time (see next paragraph). Such be-
havior is indirect evidence that our 2-bromobenzo-
phenone sample was highly pure. A similar temperature
history was observed by Babkov et al. [14], except for the
difference that their sample crystallized uneventfully
around 300 K.
Second, the vicinity around the critical point 1 in
Fig. 1 was checked for long-time stability. In Fig. 2 we
show how the phosphorescence spectrum of the initially
glassy state changed during about 20 h at a fixed tempera-
ture of 95 K. The spectrum of a fresh vitreous sample
(trace 1) is a very broad structureless band. Compared to a
similar spectrum from a neat 2-bromobenzophenone crys-
tal (curve 4), this band is positioned approximately within
the same range. Knowing that the crystal spectrum at this
temperature [1] is a superposition of the monomer and
excimer emissions, we may conclude that the glass spec-
trum either does not contain appreciable monomeric com-
ponents or they are inhomogeneously smeared so that the
monomer C=O stretch series cannot be resolved. After
20 h the spectrum (curve 2) retained its primary bell-like
shape without distinct features, its center having appre-
ciably shifted to blue during the waiting time. It is note-
worthy that this shift is in the opposite direction relative
to the phosphorescence spectrum (curve 4) of the crystal
588 Fizika Nizkikh Temperatur, 2008, v. 34, No. 6
L.M. Buravtseva, O.S. Pyshkin, M.A. Strzhemechny, and A.A. Avdeenko
100 150 200 2500
0.05
0.10
0.15
0.20
100 200 300
0
0
2
4
6
8
10
Q
u
an
tu
m
y
ie
ld
Temperature, K
Q
u
an
tu
m
y
ie
ld
,
ar
b
.
u
n
it
s
Temperature, K
1
2
Fig. 1. Temperature dependence of the relative quantum yield
of glassy 2-bromobenzophenone. The inset: comparison of the
quantum yields of the glassy (lower trace) and crystalline (up-
per trace) samples.
at the same temperature [1]. This shift suggests certain
changes in morphology but, possibly, not closer to the
crystalline order. Warmed up to room temperature and
kept so sufficiently long (about 168 h), the sample exhib-
ited a nice double-hump spectrum, characteristic of exci-
mer emission and virtually coincident with the one ob-
tained from the crystal.
Third, in order to check whether the glass state within
its domain of stability undergoes any essential relax-
ation-related changes with time, we measured phospho-
rescence spectra (see the bell-shaped curve in Fig. 3) of
vitreous 2-bromobenzophenone at 75 K, i.e., well inside
the domain of existence of the glass. Then the sample was
cooled down to liquid helium temperature and after a
three hour waiting was warmed up back to 75 K. After
that we again measured the spectrum. The difference be-
tween this spectrum and the initial one (solid curve) is
shown as the dotted curve in Fig. 3. Thus, even at a quite
high temperature the spectrum is well reproduced after
certain manipulations.
3.2. Temperature dependence of phosphorescence
spectra
Let us first discuss the spectrum of vitreous 2-bromo-
benzophenone at low temperatures where effects of pho-
non-assisted spectral kinetics are minimal. In order to
demonstrate the peculiarities of low-temperature glass
spectra, in Fig. 4 we compare them with similar spectra of
the crystal [1]. The glass spectrum has much in common
with the respective spectrum of the crystal but with con-
siderable or even cardinal differences. The low-tempera-
ture glass spectrum in Fig. 4 consists of several broad
bands separated in energy by the stretch mode frequency
of the C=O bond (about 1700 cm–1). All monomer bands
of the glass at low temperatures are broader even com-
pared with the unusually broad bands in the crystal phos-
phorescence, which can be naturally attributed to a larger
inhomogeneous broadening in the glass. Being clearly
Phosphorescence of vitreous 2-bromobenzophenone
Fizika Nizkikh Temperatur, 2008, v. 34, No. 6 589
400 450 500 550 600 650
0
0.2
0.4
0.6
0.8
1.0
1.2
4
3
2
P
h
o
sp
h
o
re
sc
en
ce
in
te
n
si
ty
Wavelength, nm
1
Fig. 2. Evolution of the phosphorescence spectrum of 2-bro-
mobenzophenone in time at a fixed temperature. The solid
trace 1 is for a freshly prepared glass sample warmed up to
95 K; the dotted trace 2 is for the same sample kept for more
than 20 h at T � 95 K; the dashed trace 3 is for the same sample
after it was kept at room temperature for about 168 h. The
spectrum protect [1] from a neat crystal of 2-bromobenzophe-
none at 95 K is shown for comparison as the dash-curve dot 4.
400 450 500 550 600 650
0
0.25
0.50
0.75
1.00
Wavelength, nm
E
m
is
si
o
n
in
te
n
si
ty
,
ar
b
.
u
n
it
s
Fig. 3. The phosphorescence spectrum from a freshly prepared
vitreous 2-bromobenzophenone at 75 K (upper solid curve)
and the difference (lower dotted curve) between this spectrum
and the one obtained after the sample was cooled down to
4.2 K, kept thus for three hours, and re-warmed back to 75 K.
350 400 450 500 550 600 650
0
0.2
0.4
0.6
0.8
1.0
Wave length, nm
P
h
o
sp
h
o
re
sc
en
ce
in
te
n
si
ty
Fig. 4. Phosphorescence spectra from a freshly prepared
glass-like 2-bromobenzophenone at 4.2 K (dot-dash line) and
111 K (solid line). The low-temperature spectrum (1.6 K) of
2-bromobenzophenone crystal protect[1] is shown as a dotted
line for comparison.
monomeric, this series is nevertheless superimposed on a
broad feature at the red side, which can be attributed as
belonging to excimer emission [15]. This first important
difference can be tentatively explained by arguing that in
a glass, unlike in the regular crystal, there are mutual po-
sitions of molecules with minimal or no energy barriers
that could preclude excimer formation. Another essential
difference between the spectra of vitreous and crystalline
2-bromobenzophenone is that only one set of equidistant
C=O stretch bands is present in the glass spectrum, rather
than two, as was reported previously for crystals [1]. We
remind here that the two equidistant sets in the crystal
were ascribed to the emission from two excited states
(stable and metastable ones), separated by approximately
1100 cm–1 with an energy barrier of approximately
100 cm–1 between them, which can be overcome via ther-
mal activation approximately at and above the liquid ni-
trogen temperature. Keeping to that interpretation, the
emission in the glass state of 2-bromobenzophenone oc-
curs from the global minimum of the triplet excited mo-
lecular state. This implies that the excited molecule in the
glass environment can easily find the pathway from the
excited (primarily metastable) state to the global mini-
mum, where it emits to C=O vibrational sublevels of the
ground state.
Variations of phosphorescence spectra of 2-bromo-
benzophenone glass with temperature are shown in Fig. 5.
At the lowest temperature of 4.2 K, the spectrum is to a
large extent monomeric. However, the spectrum clearly
contains a structureless very broad background band. As
the temperature was raised, we observed continuous
changes of the phosphorescence spectrum. Compared to
the low-temperature spectrum, the spectra at intermediate
temperatures within the domain of stability shift with
temperature progressively to red. The predominant fea-
ture is the very broad structureless maximum, with only a
host of the monomer emission series remaining. This pre-
dominant feature was shown to be due to a triplet excimer
[15]. Indeed, this very broad band appears in the glass
within the same wavelength range as in the crystal [16]
with the difference that in the glass it does not clearly re-
solve into two components. By analogy, we conclude that
to a high degree of reliability this broad band in the phos-
phorescence spectrum of the glass is also of excimer ori-
gin. The sole broad band in the phosphorescence of vitre-
ous 2-bromobenzophenone at higher temperatures (close
to 100 K) is clearly asymmetric. It can be resolved into
two Gaussian-shaped components as shown in Fig. 6. As
regards the position and the relative intensities of these
two components they are very much close to those
observed in the crystalline 2-bromobenzophenone.
4. Conclusions
The glass state of 2-bromobenzophenone was charac-
terized, using its relative phosphorescence quantum
yield, in order to establish its domain of stable existence
as well as the typical rates of morphologic changes. The
590 Fizika Nizkikh Temperatur, 2008, v. 34, No. 6
L.M. Buravtseva, O.S. Pyshkin, M.A. Strzhemechny, and A.A. Avdeenko
400 450 500 550 600 650
0
0.5
1.0
1.5
2.0
2.5
95 K
90 K
77 K
In
te
n
si
ty
,
ar
b
.u
n
it
s
Wavelengths, nm
4.2 K
Fig. 5. Phosphorescence spectra from a freshly prepared
glass-like 2-bromobenzophenone at four temperatures.
1,4 1,6 1,8 2,0 2,2 2,4 2,6 2,8
0
1
2
700 600 500 400
P
L
in
te
n
si
ty
,
ar
b
.
u
n
it
s
Energy, 10
4
cm
–1
Wavelength, nm
Fig. 6. The phosphorescence spectrum of vitreous 2-bromo-
benzophenone at 95 K resolves nicely into two Gaussian-shap-
ed subbands. The total virtually coincides with the experimen-
tal trace.
critical points at which the morphology suffered basic
transformations are at 100 and 220 K.
Phosphorescence spectra in vitreous 2-bromobenzo-
phenone have been measured as a function of temperature
over the entire domain of existence of the glassy state.
These spectra are compared with similar spectra of crys-
talline 2-bromobenzophenone. Unlike in the crystal, trip-
let excimers are formed at low temperatures. The excimer
quantum yield even at the lowest temperature exceeds
that of the monomer emission. This finding is tentatively
explained as being due to lesser steric restrictions for an
excited molecule to accommodate itself in its surround-
ing, as compared to the crystal, in order to form a bimo-
lecular excimer.
The monomeric emission comprises only one C=O
stretch series, which corresponds to the transitions from
the presumably global energy minimum [1] of an ulti-
mately relaxed excited molecule. This observation can
also find its explanation in the higher degree of con-
formational freedom of the molecule in the glass.
Though phosphorescence spectra of glassy 2-bromo-
benzophenone helps understand the nature of phospho-
rescence emission, time-resolved phosphorescence ex-
periments are needed to get a better insight into the main
mechanisms that control the spectroscopic effects ob-
served.
Acknowledgments
The authors sincerely appreciate Yu.M. Strzhemech-
ny’s informational support. The authors also thank N.A.
Davydova for a preprint of her paper [14] prior to publica-
tion as well as P.V. Zinoviev for his critical reading of the
manuscript.
1. A.A. Avdeenko, O.S. Pyshkin, V.V. Eremenko, M.A. Strzhe-
mechny, L.M. Buravtseva, and R.V. Romashkin, Fiz. Nizk.
Temp. 32, 1355 (2006) [Low Temp. Phys. 32, 1028 (2006)].
2. V.I. Melnik, Spectral Luminescence Studies of Triplet
States in Molecular Systems, Dr. Sci. Thesis, Institute of
Physics, Kiev (2006).
3. A.A. Avdeenko, T.L. Dobrovolskaya, V.A. Kulchitskii, and
Yu.V. Naboikin, Phys. Status Solidi B90, 405 (1980).
4. A.A. Avdeenko, L.M. Buravtseva, V.S. Gorobchenko, V.V.
Eremenko, S.V. Izvekov, A.E. Kravchenko, O.S. Pyshkin,
and V.I. Sugakov, Fiz. Nizk. Temp. 23, 334 (1997) [Low
Temp. Phys. 23, 247 (1997)].
5. M.D. Fayer, Exciton Coherence, in: Spectroscopy and Ex-
citation Dynamics of Condensed Molecular Systems, V.M.
Agranovich and R.M. Hochstrasser (eds.), North-Holland,
Amsterdam (1983), p.185.
6. H. B�ssler, in: Disorder Effects in Relaxational Processes
R. Richert and A. Blumen (eds.), Springer-Verlag (1994),
p. 485.
7. R. Richert and H. B »assler, Chem. Phys. Lett. 118, 235
(1985).
8. R. Richert and H. B�ssler, J. Chem. Phys. 84, 3567 (1985).
9. V.I. Melnik, Fiz. Tverd. Tela 40, 1052 (1998).
10. N.A. Davydova, V.I. Mel’nik, K.I. Nelipovitch, and
M. Drozd, J. Mol. Struct. 555, 187 (2000).
11. O.S. Pyshkin, L.M. Buravtseva, and M.A. Strzhemechny
(in prepartion).
12. V.N. Baumer, R.V. Romashkin, M.A. Strzhemechny, A.A.
Avdeenko, O.S. Pyshkin, R.I. Zubatyuk, and L.M. Burav-
tseva, Acta Crystallogr. E61, o1170 (2005).
13. S.W. Mao and N. Hirota, Molec. Phys. 27, 327 (1974).
14. L.M. Babkov, J. Baran, N.A. Davydova, D. Drozd, O.S.
Pyshkin, and K.E. Uspenskiy (submitted to J. Mol. Struct.).
15. O.S. Pyshkin, Fiz. Nizk. Temp. 33, 1411 (2007) [Low
Temp. Phys. 33, 1077 (2007)].
16. M.A. Strzhemechny, A.A. Avdeenko, V.V. Eremenko,
O.S. Pyshkin, and L.M. Buravtseva, Chem. Phys. Lett. 431,
300 (2006).
Phosphorescence of vitreous 2-bromobenzophenone
Fizika Nizkikh Temperatur, 2008, v. 34, No. 6 591
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