Drift tube–mass spectrometers are now used extensively to measure the rate coefficients of ion–molecule reactions. The accuracy which can be obtained in favorable cases is about 10%, but if careful attention is not paid to a number of factors, very large errors can result. The purpose of this paper is to call attention to this fact, which seems not to be widely known, and to enumerate the factors which can lead to these large errors.

1.
D. L.
Albritton
,
T. M.
Miller
,
D. W.
Martin
, and
E. W.
McDaniel
,
Phys. Rev.
171
,
94
(
1968
).
2.
T. M.
Miller
,
J. T.
Moseley
,
D. W.
Martin
, and
E. W.
McDaniel
,
Phys. Rev.
173
,
115
(
1968
).
3.
J. T.
Moseley
,
R. M.
Snuggs
,
D. W.
Martin
, and
E. W.
McDaniel
,
Phys. Rev. Letters
21
,
873
(
1968
).
4.
J. T.
Moseley
,
I. R.
Gatland
,
D. W.
Martin
, and
E. W.
McDaniel
,
Phys. Rev.
178
,
234
(
1969
).
5.
J. T.
Moseley
,
R. M.
Snuggs
,
D. W.
Martin
, and
E. W.
McDaniel
,
Phys. Rev.
178
,
240
(
1969
).
6.
K. B.
McAfee
,
D.
Sipler
, and
D.
Edelson
,
Phys. Rev.
160
,
130
(
1967
).
7.
L. G.
McKnight
,
K. B.
McAfee
, and
D. P.
Sipler
,
Phys. Rev.
164
,
62
(
1967
).
8.
D.
Edelson
,
J. A.
Morrison
,
L. G.
McKnight
, and
D. P.
Sipler
,
Phys. Rev.
164
,
71
(
1967
).
9.
M.
Saporoschenko
,
Phys. Rev.
139
,
A349
,
A352
(
1965
).
10.
M.
Saporoschenko
,
J. Chem. Phys.
49
,
768
(
1968
).
11.
J. M.
Madson
,
H. J.
Oskam
, and
L. M.
Chanin
,
Phys. Rev. Letters
15
,
1018
(
1965
).
12.
G. F.
Sauter
,
R. A.
Gerber
, and
H. J.
Oskam
,
Rev. Sci. Instr.
37
,
572
(
1966
).
13.
J. L.
Moruzzi
and
A. V.
Phelps
,
J. Chem. Phys.
45
,
4617
(
1966
).
14.
Y.
Kaneko
,
L. R.
Megill
, and
J. B.
Hasted
,
J. Chem. Phys.
45
,
3741
(
1966
).
15.
D. K.
Bohme
,
P. P.
Ong
,
J. B.
Hasted
, and
L. R.
Megill
,
Planetary Sci.
15
,
1777
(
1967
).
16.
D. K.
Bohme
,
J. B.
Hasted
, and
P. P.
Ong
,
Chem. Phys. Letters
1
,
259
(
1967
).
17.
D. K.
Bohme
,
J. B.
Hasted
, and
P. P.
Ong
,
J. Phys. B
1
,
879
(
1968
).
18.
P. P.
Ong
and
J. B.
Hasted
,
J. Phys. B
2
,
91
(
1969
).
19.
D. E.
Golden
,
G.
Sinnott
, and
R. N.
Varney
,
Phys. Rev. Letters
20
,
239
(
1968
).
20.
G.
Sinnott
,
D. W.
Golden
, and
R. N.
Varney
,
Phys. Rev.
170
,
272
(
1968
).
21.
R. N.
Varney
,
Phys. Rev.
174
,
165
(
1968
).
22.
J.
Heimerl
,
R.
Johnsen
, and
M. A.
Biondi
,
J. Chem. Phys.
51
,
5041
(
1969
).
23.
Y.
Kaneko
,
N.
Kobayashi
, and
I.
Kanomata
,
J. Phys. Soc. Japan
27
,
992
(
1969
).
24.
Much of the advantage of a movable ion source can be achieved with a stationary ion source by use of the “ping‐pong” technique of Biondi and his colleagues,22 in which the drift field is reversed for some desired time interval during the ion transit and then reversed again to send the ions toward the exit aperture. This technique, however, does not permit the use of very short drift distances, which are useful in the study of fast reactions.
25.
J. H.
Whealton
and
S. B.
Woo
,
Phys. Rev. Letters
20
,
1137
(
1968
);
S. B.
Woo
and
J. H.
Whealton
,
Phys. Rev.
180
,
314
(
1969
).
26.
In his recent determinations of reaction rates, Dr. L. G. McKnight allows for a factor of 2 due to the mass discrimination effects mentioned here. This allowance is based on measurements of the discrimination occurring between ions with masses of 16 and 48 amu (private communication, 1969).
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