Speaker
Thuy Dung Tran
Description
See the full Abstract at http://ocs.ciemat.es/EPS2018ABS/pdf/P4.4013.pdf
The reaction of O+ with HD at low temperatures
T. D. Tran1, A. Kovalenko1, S. Rednyk1, Š. Roučka1, R. Plašil1 and J. Glosík1
1 Department of Surface and Plasma Science, Faculty of Mathematics and Physics, Charles
University, Prague, Czech Republic
The reaction of O+ with HD has two channels
𝑘OH
O+ + HD → OH++ D, (1)
𝑘OD
→ OD++ H. (2)
The total reaction rate coefficient is the sum of rate coefficients of both channels k = kOH + kOD
reaction. k and the isotopic branching ratio kOH/k have been measured as a function of
temperature using a 22-pole ion trap apparatus [1]. The apparatus allows measuring reaction
rate coefficients in the temperature range 15 – 300 K. The systematic uncertainty of
measurement is 20 %. First results are shown in the figure. Our measurements will be compared
with previous studies, where the lowest measuring temperature is 93 K [2,3,4].
1000
100 +
OHD , OH + (a) (b)
3 O+
OH+
OD+, OH2+ 100
10
OD+, OH2+ T22PT = 25.9 K
Ni(t)
Ni(t)
T22PT = 26.1 K OH+
[He] = 3.5·1013 cm–3
1 [He] = 3.4·1013 cm–3 10
[HD] = 3.5·1010 cm–3
[HD] = 4.2·1011 cm–3 OHD+, OH3+
k = (1.48 )·10–9 cm3s–1
k = (1.50 0.04)10–9 cm3s–1 O +
kOH/k = 0.53
0.1 1
0 2 4 6 8 10 12 0 2 4 6 8 10 12 14 16 18 20
t (ms) t (ms)
Figure: Example of time evolution of numbers of O+ ( ), OH+ ( ), OD+ and OH2+ ( ), OHD+ and OH3+ ( ) ions
at low temperatures in the trap. Ions of the same mass cannot be distinguished from each other. Ions OHD+, OH3+
and other products OD2+, ODH2+ and H+ are not involved in fit model. (a) Measurement with high number density
of HD. The rate of reaction is too fast to observe production of OH + and OD+. However, by fitting a decay of O+
we can get the total reaction rate coefficient k. (b) Measurement with low number density of HD. k and also kOH,
kOD can be determined.
Acknowledgments: We thank the Technical University of Chemnitz and the DFG for lending us the 22-pole ion trap instrument and professor Dieter Gerlich for
discussion. This work is partly supported by GACR Grant No. 17-19459S and 17-18067S, by GAUK Grant No. 1584217 and 1168216.
References
[1] Gerlich, D., et al., J. Phys. Chem. A, 2013, 117(39), 10068-10075.
[2] Dateo, C. E., & Clary, D. C., J. Chem. Soc. Faraday Trans. 2, 1989, 85(10), 1685-1696.
[3] Sunderlin, L. S., et al., 1990, Chem. Phys. Lett., 167(3), 188-192.
[4] Viggiano, A. A., et al., 1991, J. Chem. Phys., 95(11), 8120-8123.
