M. Anti˜nolo et al. / Journal of Photochemistry and Photobiology A: Chemistry 231 (2012) 33–40
39
Dissociation from T1 is also possible at low pressures. According
to that mechanism, the SV plots can be described by the following
equation [32]:
˚ꢁ = 308 nm was observed, i.e. ˚ꢁ = 308 nm decreases at high total pres-
sures. A slight curvature in the Stern–Volmer plot was noticeable at
low pressures, indicating that two excited states of CF3(CH2)2CHO
(the singlet S1 and triplet T1 states) seem to be involved in the
dissociation mechanism. For atmospheric modeling purposes, the
derived high-pressure SV equation should be an adequate descrip-
tion of the photolysis of CF3(CH2)2CHO.
In the presence of air, the photolysis of CF3(CH2)2CHO at
308 nm mainly produces HCO and CF3(CH2)2 radicals, which in
the presence of O2 finally form CO, HC(O)OH, CF3CH2CHO, and
CF3CH2CH2OH. Further photodegradation of CF3CH2CHO yields
shorter fluoroaldehydes and fluoroalcohols.
1
(1 + a2 + a1[M])(1 + a3[M])
1 + a2 + a3[M]
=
(E10)
˚
ꢁ=308 nm
where a1 = kMS/kdS, a2 = kISC/kdS and a3 = kMT/kdT, where ˚0
is taken as unity. In the high-pressure regime, Eq. (E10) is simplified
ꢁ=308 nm
as:
1
≈ 1 + a2 + a1[M]
(E11)
˚
ꢁ=308 nm
a1 = kMS/kdS = (1.71 0.17) × 10−19 cm3 molecule−1
is
derived
Acknowledgements
and a2 was obtained (kISC/kdS = 0.62 0.11) from the intercept of
such a plot. Under these conditions, the photolysis mechanism
occurs exclusively by the dissociation of S1. In Fig. 4b, a fit of the
data to Eq. (E10) is depicted by a solid line. a2 was fixed in the
analysis of data, getting a1 = (1.76 0.06) × 10−19 cm3 molecule−1
The authors would like to thank the Spanish Ministerio de
Ciencia e Innovación (MICINN) (CGL2007-61835/CLI and CGL2010-
19066) and the Consejería de Educación y Ciencia de la Junta de
Comunidades de Castilla-La Mancha (PAI-05-062 and PEII11-0279-
8538) for supporting this Project. Also, M. Antin˜olo wishes to thank
MICINN for providing her a grant.
and a3 = (1.44 0.84) × 10−18 cm3 molecule−1
.
be an adequate description of the photolysis of CF3(CH2)2CHO.
Under our experimental conditions, the gas mixtures approxi-
mately contain 74% of N2, 19% of O2, 6% of cyclohexane and 0.2% of
CF3(CH2)2CHO at all pressures. Since [M] is the sum of the concen-
tration of all possible quenchers present, Eq. (E11) can be rewritten
as:
Appendix A. Supplementary data
Supplementary data associated with this article can be found, in
ꢂ
ꢃ
0
kO
kN
˚
kCHex
= 1 + 2 [O2] + 2 [N2] +
[C6H12]
References
˚
kdS
kdS
kdS
ꢁ=308 nm
kSQ
kdS
+
[CF3(CH2)2CHO]
(E12)
[2] X. Tang, S. Madronich, T. Wallington, D. Calamari, Changes in tropospheric
composition and air quality, J. Photochem. Photobiol. B 46 (1998) 83–95.
[3] Ch. George, J.Y. Saison, J.L. Ponche, Ph. Mirabel, Kinetics of mass transfer of
carbonyl fluoride, trifluoroacetyl fluoride, and trifluoroacetyl chloride at the
air/water interface, J. Phys. Chem. 98 (1994) 10857–10862.
[4] M.D. Hurley, T.J. Wallington, M.P. Sulbaek Andersen, D.A. Ellis, J.W. Martin,
S.A. Mabury, Atmospheric chemistry of fluorinated alcohols: reaction with cl
atoms and oh radicals and atmospheric lifetimes, J. Phys. Chem. A 108 (2004)
1973–1979.
[5] S.R. Sellevåg, C.J. Nielsen, O.A. Søvde, G. Myhre, J.K. Sundet, F.I. Stordal, S.A.
Isaken, Atmospheric gas-phase degradation and global warming potentials of
2-fluoroethanol, 2,2-difluoroethanol, and 2,2,2-trifluoroethanol, Atmos. Envi-
ron. 38 (2004) 6725–6735.
[6] M.D. Hurley, J.C. Misner, J.A. Ball, T.J. Wallington, D.A. Ellis, S.A. Mabury, Atmo-
spheric chemistry of CF3CH2CH2OH: kinetics, mechanisms and products of Cl
atom and OH radical initiated oxidation in the presence and absence of NOx, J.
Phys. Chem. A 109 (2005) 9816–9826.
[7] T. Kelly, V. Bossoutrot, I. Magneron, K. Wirtz, J. Treacy, A. Mellouki, H. Sidebot-
tom, G. Le Bras, A kinetic and mechanistic study of the reactions of OH radicals
and Cl atoms with 3,3,3-trifluoropropanol under atmospheric conditions, J.
Phys. Chem. A 109 (2005) 347–355.
[8] D.J. Scollard, J.J. Treacy, H.W. Sidebottom, C. Balestra-Garcia, G. Laverdet, G.
Lebras, H. MacLeod, S. Teton, Rate constants for the reactions of hydroxyl radi-
cals and chlorine atoms with halogenated aldehydes, J. Phys. Chem. 97 (1993)
4683–4688.
[9] M.P. Sulbaek Andersen, O.J. Nielsen, M.D. Hurley, J.C. Ball, T.J. Wallington,
J.E. Stevens, J.W. Martin, D.A. Ellis, S.A. Mabury, Atmospheric chemistry of
n–CxF2x+1CHO (x = 1, 3, 4): reaction with Cl atoms, OH radicals and IR spectra of
CxF2x+1C(O)O2NO2, J. Phys. Chem. A 108 (2004) 5189–5196.
[10] M. Antin˜olo, E. Jiménez, A. Notario, E. Martínez, J. Albaladejo, Tropospheric pho-
tooxidation of CF3CH2CHO and CF3(CH2)2CHO initiated by Cl atoms and OH
radicals, Atmos. Chem. Phys. 10 (2010) 1911–1922.
ki (i = O2, N2, C6H12) are the quenching rate coefficient for these
gases and kSQ, is the rate coefficient for the self-quenching. Taking
into account the composition of the gas mixture, it is simplified to:
ꢂ
ꢃ
0
˚
˚
ꢁ=308 nm
ꢄ
ꢅ
0.19kO
0.74kN
0.002kSQ
0.06kCHex
2
2
= 1 +
+
+
+
[M]
kdS
kdS
kdS
kdS
(E13)
At high pressures, cyclohexane and CF3(CH2)2CHO concentrations
are sufficiently low to affect the quenching of S1, even if an upper
ing quenching rate coefficients. In all cases the main contributor to
collisional deactivation of S1 is the bath gas.
by Tadic´ et al. between 275 and 380 nm [31]. The pressure quench-
ing of butanal was reported to be weaker than that observed for
CF3(CH2)2CHO. The obtained photolysis quantum yield for butanal
at zero pressure was 0.55 and the Stern–Volmer constant was
5.96 × 10−20 cm3 molecule−1 [31]. These authors also attributed the
deviation of unity of ˚0ꢁ to the existence of other energy-dissipating
processes, possibly, the deactivation of the triplet state of butanal
by phosphorescence.
[11] S.R. Sellevåg, T. Kelly, H. Sidebottom, C.J. Nielsen, A study of the IR and UV–vis
absorption cross-sections, photolysis and OH-initiated oxidation of CF3CHO
and CF3CH2CHO, Phys. Chem. Chem. Phys. 6 (2004) 1243–1252.
[12] Y. Hashikawa, M. Kawasaki, R.L. Waterland, M.D. Hurley, J.C. Ball, T.J. Walling-
ton, M.P. Sulbaek Andersen, O.J. Nielsen, Gas phase UV and IR absorption spectra
of CxF2x+1CHO (x = 1–4), J. Fluoresc. Chem. 125 (2004) 1925–1932.
[13] M.S. Chiappero, F.E. Malanca, G.A. Argüello, S.T. Wooldridge, M.D. Hurley, J.C.
Ball, T.J. Wallington, R.L. Waterland, R.C. Buck, Atmospheric chemistry of per-
fluoroaldehydes (CxF2x+1CHO) and fluorotelomer aldehydes (CxF2x+1CH2CHO):
quantification of the important role of photolysis, J. Phys. Chem. A 110 (2006)
11944–11953.
4. Conclusions
In conclusion, we present the first photochemical study of 4,4,4-
trifluorobutanal, CF3(CH2)2CHO. Absorption cross sections, ꢀꢁ(T),
were determined as a function of wavelength (230–340 nm) and
temperature (269–323 K). Additionally, the photolysis quantum
yields of CF3(CH2)2CHO at 308 nm, ˚ꢁ = 308 nm, are reported here
between 20.5 and 760 Torr. A negative pressure dependence of
[14] M. Antin˜olo, E. Jiménez, J. Albaladejo, UV absorption cross sections between
230 and 350 nm and pressure dependence of the photolysis quantum yield at
308 nm of CF3CH2CHO, Phys. Chem. Chem. Phys. 13 (2011) 15936–15946.